update 'Merge' of the 'Config'

.golangci.yml

@@ -59,7 +59,6 @@ linters:
         - inamedparam
         - interfacebloat
         - intrange
-        - ireturn
         - loggercheck
         - makezero
         - mirror
@@ -110,6 +109,7 @@ linters:
                   - perfsprint
                   - errcheck
                   - gosec
+                  - gocyclo
 
             - path: _test\.go$
               linters:

cmd/cli/main.go

@@ -4,16 +4,27 @@ import (
 	"fmt"
 	"os"
 
-	"github.com/aykhans/dodo/pkg/config"
+	"github.com/aykhans/dodo/pkg/config/parser"
 	"github.com/aykhans/dodo/pkg/types"
 	"github.com/aykhans/dodo/pkg/utils"
 	"github.com/jedib0t/go-pretty/v6/text"
+	"github.com/k0kubun/pp/v3"
 )
 
 func main() {
-	cliParser := config.NewConfigCLIParser(os.Args)
+	envParser := parser.NewConfigENVParser("DODO")
-	cfg, err := cliParser.Parse()
+	envConfig, err := envParser.Parse()
+	_ = utils.HandleErrorOrDie(err,
+		utils.OnCustomError(func(err types.FieldParseErrors) error {
+			printValidationErrors("ENV", err.Errors...)
+			fmt.Println()
+			os.Exit(1)
+			return nil
+		}),
+	)
 
+	cliParser := parser.NewConfigCLIParser(os.Args)
+	cliConf, err := cliParser.Parse()
 	_ = utils.HandleErrorOrDie(err,
 		utils.OnSentinelError(types.ErrCLINoArgs, func(err error) error {
 			cliParser.PrintHelp()
@@ -35,11 +46,16 @@ func main() {
 		}),
 	)
 
-	fmt.Println(cfg)
+	envConfig.Merge(cliConf)
+	pp.Println(cliConf)   //nolint
+	pp.Println(envConfig) //nolint
 }
 
 func printValidationErrors(parserName string, errors ...types.FieldParseError) {
 	for _, fieldErr := range errors {
-		utils.PrintErr(text.FgRed, "[%s] Field '%s': %v", parserName, fieldErr.Field, fieldErr.Err)
+		if fieldErr.Value == "" {
+			utils.PrintErr(text.FgYellow, "[%s] Field '%s': %v", parserName, fieldErr.Field, fieldErr.Err)
+		}
+		utils.PrintErr(text.FgYellow, "[%s] Field '%s' (%s): %v", parserName, fieldErr.Field, fieldErr.Value, fieldErr.Err)
 	}
 }

go.mod

@@ -4,15 +4,18 @@ go 1.25
 
 require (
 	github.com/jedib0t/go-pretty/v6 v6.6.8
+	github.com/k0kubun/pp/v3 v3.5.0
 	github.com/stretchr/testify v1.10.0
 )
 
 require (
 	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/mattn/go-colorable v0.1.14 // indirect
+	github.com/mattn/go-isatty v0.0.20 // indirect
 	github.com/mattn/go-runewidth v0.0.16 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/rivo/uniseg v0.4.7 // indirect
 	golang.org/x/sys v0.30.0 // indirect
-	golang.org/x/text v0.22.0 // indirect
+	golang.org/x/text v0.26.0 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 )

go.sum

@@ -2,6 +2,12 @@ github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/jedib0t/go-pretty/v6 v6.6.8 h1:JnnzQeRz2bACBobIaa/r+nqjvws4yEhcmaZ4n1QzsEc=
 github.com/jedib0t/go-pretty/v6 v6.6.8/go.mod h1:YwC5CE4fJ1HFUDeivSV1r//AmANFHyqczZk+U6BDALU=
+github.com/k0kubun/pp/v3 v3.5.0 h1:iYNlYA5HJAJvkD4ibuf9c8y6SHM0QFhaBuCqm1zHp0w=
+github.com/k0kubun/pp/v3 v3.5.0/go.mod h1:5lzno5ZZeEeTV/Ky6vs3g6d1U3WarDrH8k240vMtGro=
+github.com/mattn/go-colorable v0.1.14 h1:9A9LHSqF/7dyVVX6g0U9cwm9pG3kP9gSzcuIPHPsaIE=
+github.com/mattn/go-colorable v0.1.14/go.mod h1:6LmQG8QLFO4G5z1gPvYEzlUgJ2wF+stgPZH1UqBm1s8=
+github.com/mattn/go-isatty v0.0.20 h1:xfD0iDuEKnDkl03q4limB+vH+GxLEtL/jb4xVJSWWEY=
+github.com/mattn/go-isatty v0.0.20/go.mod h1:W+V8PltTTMOvKvAeJH7IuucS94S2C6jfK/D7dTCTo3Y=
 github.com/mattn/go-runewidth v0.0.16 h1:E5ScNMtiwvlvB5paMFdw9p4kSQzbXFikJ5SQO6TULQc=
 github.com/mattn/go-runewidth v0.0.16/go.mod h1:Jdepj2loyihRzMpdS35Xk/zdY8IAYHsh153qUoGf23w=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
@@ -11,10 +17,11 @@ github.com/rivo/uniseg v0.4.7 h1:WUdvkW8uEhrYfLC4ZzdpI2ztxP1I582+49Oc5Mq64VQ=
 github.com/rivo/uniseg v0.4.7/go.mod h1:FN3SvrM+Zdj16jyLfmOkMNblXMcoc8DfTHruCPUcx88=
 github.com/stretchr/testify v1.10.0 h1:Xv5erBjTwe/5IxqUQTdXv5kgmIvbHo3QQyRwhJsOfJA=
 github.com/stretchr/testify v1.10.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
+golang.org/x/sys v0.6.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.30.0 h1:QjkSwP/36a20jFYWkSue1YwXzLmsV5Gfq7Eiy72C1uc=
 golang.org/x/sys v0.30.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
-golang.org/x/text v0.22.0 h1:bofq7m3/HAFvbF51jz3Q9wLg3jkvSPuiZu/pD1XwgtM=
+golang.org/x/text v0.26.0 h1:P42AVeLghgTYr4+xUnTRKDMqpar+PtX7KWuNQL21L8M=
-golang.org/x/text v0.22.0/go.mod h1:YRoo4H8PVmsu+E3Ou7cqLVH8oXWIHVoX0jqUWALQhfY=
+golang.org/x/text v0.26.0/go.mod h1:QK15LZJUUQVJxhz7wXgxSy/CJaTFjd0G+YLonydOVQA=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=

pkg/config/config.go

@@ -29,6 +29,7 @@ var Defaults = struct {
 var SupportedProxySchemes []string = []string{"http", "socks5", "socks5h"}
 
 type Config struct {
+	Files        []types.ConfigFile
 	Method       *string
 	URL          *url.URL
 	Timeout      *time.Duration
@@ -48,7 +49,8 @@ func NewConfig() *Config {
 	return &Config{}
 }
 
-func (config *Config) MergeConfig(newConfig *Config) {
+func (config *Config) Merge(newConfig *Config) {
+	config.Files = append(config.Files, newConfig.Files...)
 	if newConfig.Method != nil {
 		config.Method = newConfig.Method
 	}
@@ -74,19 +76,19 @@ func (config *Config) MergeConfig(newConfig *Config) {
 		config.SkipVerify = newConfig.SkipVerify
 	}
 	if len(newConfig.Params) != 0 {
-		config.Params = newConfig.Params
+		config.Params.Append(newConfig.Params...)
 	}
 	if len(newConfig.Headers) != 0 {
-		config.Headers = newConfig.Headers
+		config.Headers.Append(newConfig.Headers...)
 	}
 	if len(newConfig.Cookies) != 0 {
-		config.Cookies = newConfig.Cookies
+		config.Cookies.Append(newConfig.Cookies...)
 	}
 	if len(newConfig.Bodies) != 0 {
-		config.Bodies = newConfig.Bodies
+		config.Bodies.Append(newConfig.Bodies...)
 	}
 	if len(newConfig.Proxies) != 0 {
-		config.Proxies = newConfig.Proxies
+		config.Proxies.Append(newConfig.Proxies...)
 	}
 }
 

pkg/config/config_test.go

@@ -23,6 +23,7 @@ func TestMergeConfig(t *testing.T) {
 		newDuration := 2 * time.Minute
 
 		config := &Config{
+			Files:        []types.ConfigFile{},
 			Method:       utils.ToPtr("GET"),
 			URL:          originalURL,
 			Timeout:      &originalTimeout,
@@ -39,6 +40,7 @@ func TestMergeConfig(t *testing.T) {
 		}
 
 		newConfig := &Config{
+			Files:        []types.ConfigFile{},
 			Method:       utils.ToPtr("POST"),
 			URL:          newURL,
 			Timeout:      &newTimeout,
@@ -54,7 +56,7 @@ func TestMergeConfig(t *testing.T) {
 			Proxies:      types.Proxies{},
 		}
 
-		config.MergeConfig(newConfig)
+		config.Merge(newConfig)
 
 		assert.Equal(t, "POST", *config.Method)
 		assert.Equal(t, newURL, config.URL)
@@ -64,10 +66,10 @@ func TestMergeConfig(t *testing.T) {
 		assert.Equal(t, newDuration, *config.Duration)
 		assert.True(t, *config.Yes)
 		assert.True(t, *config.SkipVerify)
-		assert.Equal(t, types.Params{{Key: "new", Value: []string{"value"}}}, config.Params)
+		assert.Equal(t, types.Params{{Key: "old", Value: []string{"value"}}, {Key: "new", Value: []string{"value"}}}, config.Params)
-		assert.Equal(t, types.Headers{{Key: "New-Header", Value: []string{"new"}}}, config.Headers)
+		assert.Equal(t, types.Headers{{Key: "Old-Header", Value: []string{"old"}}, {Key: "New-Header", Value: []string{"new"}}}, config.Headers)
-		assert.Equal(t, types.Cookies{{Key: "newCookie", Value: []string{"newValue"}}}, config.Cookies)
+		assert.Equal(t, types.Cookies{{Key: "oldCookie", Value: []string{"oldValue"}}, {Key: "newCookie", Value: []string{"newValue"}}}, config.Cookies)
-		assert.Equal(t, types.Bodies{types.Body("new body")}, config.Bodies)
+		assert.Equal(t, types.Bodies{types.Body("old body"), types.Body("new body")}, config.Bodies)
 		assert.Empty(t, config.Proxies)
 	})
 
@@ -76,6 +78,7 @@ func TestMergeConfig(t *testing.T) {
 		originalTimeout := 5 * time.Second
 
 		config := &Config{
+			Files:      []types.ConfigFile{},
 			Method:     utils.ToPtr("GET"),
 			URL:        originalURL,
 			Timeout:    &originalTimeout,
@@ -85,11 +88,12 @@ func TestMergeConfig(t *testing.T) {
 
 		newURL, _ := url.Parse("https://new.example.com")
 		newConfig := &Config{
+			Files:      []types.ConfigFile{},
 			URL:        newURL,
 			DodosCount: utils.ToPtr(uint(10)),
 		}
 
-		config.MergeConfig(newConfig)
+		config.Merge(newConfig)
 
 		assert.Equal(t, "GET", *config.Method, "Method should remain unchanged")
 		assert.Equal(t, newURL, config.URL, "URL should be updated")
@@ -103,6 +107,7 @@ func TestMergeConfig(t *testing.T) {
 		originalTimeout := 5 * time.Second
 
 		config := &Config{
+			Files:      []types.ConfigFile{},
 			Method:     utils.ToPtr("GET"),
 			URL:        originalURL,
 			Timeout:    &originalTimeout,
@@ -112,6 +117,7 @@ func TestMergeConfig(t *testing.T) {
 		}
 
 		newConfig := &Config{
+			Files:      []types.ConfigFile{},
 			Method:     nil,
 			URL:        nil,
 			Timeout:    nil,
@@ -121,7 +127,7 @@ func TestMergeConfig(t *testing.T) {
 		}
 
 		originalConfigCopy := *config
-		config.MergeConfig(newConfig)
+		config.Merge(newConfig)
 
 		assert.Equal(t, originalConfigCopy.Method, config.Method)
 		assert.Equal(t, originalConfigCopy.URL, config.URL)
@@ -132,7 +138,9 @@ func TestMergeConfig(t *testing.T) {
 	})
 
 	t.Run("MergeConfig with empty slices", func(t *testing.T) {
+		configFile, _ := types.ParseConfigFile("original.yml")
 		config := &Config{
+			Files:   []types.ConfigFile{*configFile},
 			Params:  types.Params{{Key: "original", Value: []string{"value"}}},
 			Headers: types.Headers{{Key: "Original-Header", Value: []string{"original"}}},
 			Cookies: types.Cookies{{Key: "originalCookie", Value: []string{"originalValue"}}},
@@ -141,6 +149,7 @@ func TestMergeConfig(t *testing.T) {
 		}
 
 		newConfig := &Config{
+			Files:   []types.ConfigFile{},
 			Params:  types.Params{},
 			Headers: types.Headers{},
 			Cookies: types.Cookies{},
@@ -148,8 +157,9 @@ func TestMergeConfig(t *testing.T) {
 			Proxies: types.Proxies{},
 		}
 
-		config.MergeConfig(newConfig)
+		config.Merge(newConfig)
 
+		assert.Equal(t, []types.ConfigFile{*configFile}, config.Files, "Empty Files should not override")
 		assert.Equal(t, types.Params{{Key: "original", Value: []string{"value"}}}, config.Params, "Empty Params should not override")
 		assert.Equal(t, types.Headers{{Key: "Original-Header", Value: []string{"original"}}}, config.Headers, "Empty Headers should not override")
 		assert.Equal(t, types.Cookies{{Key: "originalCookie", Value: []string{"originalValue"}}}, config.Cookies, "Empty Cookies should not override")
@@ -157,6 +167,28 @@ func TestMergeConfig(t *testing.T) {
 		assert.Equal(t, types.Proxies{}, config.Proxies, "Empty Proxies should not override")
 	})
 
+	t.Run("MergeConfig with Files field", func(t *testing.T) {
+		configFile1, _ := types.ParseConfigFile("config1.yml")
+		configFile2, _ := types.ParseConfigFile("config2.yaml")
+
+		config := &Config{
+			Files:   []types.ConfigFile{*configFile1},
+			Method:  utils.ToPtr("GET"),
+			Headers: types.Headers{{Key: "Original-Header", Value: []string{"original"}}},
+		}
+
+		newConfig := &Config{
+			Files:  []types.ConfigFile{*configFile2},
+			Method: utils.ToPtr("POST"),
+		}
+
+		config.Merge(newConfig)
+
+		assert.Equal(t, "POST", *config.Method, "Method should be updated")
+		assert.Equal(t, []types.ConfigFile{*configFile1, *configFile2}, config.Files, "Files should be appended")
+		assert.Equal(t, types.Headers{{Key: "Original-Header", Value: []string{"original"}}}, config.Headers, "Headers should remain unchanged")
+	})
+
 	t.Run("MergeConfig on empty original config", func(t *testing.T) {
 		config := &Config{}
 
@@ -165,6 +197,7 @@ func TestMergeConfig(t *testing.T) {
 		newDuration := 2 * time.Minute
 
 		newConfig := &Config{
+			Files:        []types.ConfigFile{},
 			Method:       utils.ToPtr("POST"),
 			URL:          newURL,
 			Timeout:      &newTimeout,
@@ -180,7 +213,7 @@ func TestMergeConfig(t *testing.T) {
 			Proxies:      types.Proxies{},
 		}
 
-		config.MergeConfig(newConfig)
+		config.Merge(newConfig)
 
 		assert.Equal(t, "POST", *config.Method)
 		assert.Equal(t, newURL, config.URL)
@@ -246,6 +279,7 @@ func TestSetDefaults(t *testing.T) {
 
 	t.Run("SetDefaults adds User-Agent when missing", func(t *testing.T) {
 		config := &Config{
+			Files:   []types.ConfigFile{},
 			Headers: types.Headers{{Key: "Content-Type", Value: []string{"application/json"}}},
 		}
 
@@ -268,6 +302,7 @@ func TestSetDefaults(t *testing.T) {
 
 	t.Run("SetDefaults with partial config", func(t *testing.T) {
 		config := &Config{
+			Files:  []types.ConfigFile{},
 			Method: utils.ToPtr("PUT"),
 			Yes:    utils.ToPtr(true),
 		}
@@ -306,6 +341,7 @@ func TestSetDefaults(t *testing.T) {
 
 	t.Run("SetDefaults with empty Headers initializes correctly", func(t *testing.T) {
 		config := &Config{
+			Files:   []types.ConfigFile{},
 			Headers: types.Headers{},
 		}
 
@@ -316,3 +352,176 @@ func TestSetDefaults(t *testing.T) {
 		assert.Equal(t, Defaults.UserAgent, config.Headers[0].Value[0])
 	})
 }
+
+func TestMergeConfig_AppendBehavior(t *testing.T) {
+	t.Run("MergeConfig appends params with same key", func(t *testing.T) {
+		config := &Config{
+			Params: types.Params{{Key: "filter", Value: []string{"active"}}},
+		}
+
+		newConfig := &Config{
+			Params: types.Params{{Key: "filter", Value: []string{"verified"}}},
+		}
+
+		config.Merge(newConfig)
+
+		assert.Len(t, config.Params, 1)
+		paramValue := config.Params.GetValue("filter")
+		require.NotNil(t, paramValue)
+		assert.Equal(t, []string{"active", "verified"}, *paramValue)
+	})
+
+	t.Run("MergeConfig appends headers with same key", func(t *testing.T) {
+		config := &Config{
+			Headers: types.Headers{{Key: "Accept", Value: []string{"text/html"}}},
+		}
+
+		newConfig := &Config{
+			Headers: types.Headers{{Key: "Accept", Value: []string{"application/json"}}},
+		}
+
+		config.Merge(newConfig)
+
+		assert.Len(t, config.Headers, 1)
+		headerValue := config.Headers.GetValue("Accept")
+		require.NotNil(t, headerValue)
+		assert.Equal(t, []string{"text/html", "application/json"}, *headerValue)
+	})
+
+	t.Run("MergeConfig appends cookies with same key", func(t *testing.T) {
+		config := &Config{
+			Cookies: types.Cookies{{Key: "session", Value: []string{"old_token"}}},
+		}
+
+		newConfig := &Config{
+			Cookies: types.Cookies{{Key: "session", Value: []string{"new_token"}}},
+		}
+
+		config.Merge(newConfig)
+
+		assert.Len(t, config.Cookies, 1)
+		cookieValue := config.Cookies.GetValue("session")
+		require.NotNil(t, cookieValue)
+		assert.Equal(t, []string{"old_token", "new_token"}, *cookieValue)
+	})
+
+	t.Run("MergeConfig appends bodies", func(t *testing.T) {
+		config := &Config{
+			Bodies: types.Bodies{types.Body("first body")},
+		}
+
+		newConfig := &Config{
+			Bodies: types.Bodies{types.Body("second body"), types.Body("third body")},
+		}
+
+		config.Merge(newConfig)
+
+		assert.Len(t, config.Bodies, 3)
+		assert.Equal(t, types.Body("first body"), config.Bodies[0])
+		assert.Equal(t, types.Body("second body"), config.Bodies[1])
+		assert.Equal(t, types.Body("third body"), config.Bodies[2])
+	})
+
+	t.Run("MergeConfig appends proxies", func(t *testing.T) {
+		proxy1URL, _ := url.Parse("http://proxy1.example.com:8080")
+		proxy2URL, _ := url.Parse("http://proxy2.example.com:8080")
+		proxy3URL, _ := url.Parse("https://proxy3.example.com:443")
+
+		config := &Config{
+			Proxies: types.Proxies{types.Proxy(*proxy1URL)},
+		}
+
+		newConfig := &Config{
+			Proxies: types.Proxies{types.Proxy(*proxy2URL), types.Proxy(*proxy3URL)},
+		}
+
+		config.Merge(newConfig)
+
+		assert.Len(t, config.Proxies, 3)
+		assert.Equal(t, "http://proxy1.example.com:8080", config.Proxies[0].String())
+		assert.Equal(t, "http://proxy2.example.com:8080", config.Proxies[1].String())
+		assert.Equal(t, "https://proxy3.example.com:443", config.Proxies[2].String())
+	})
+
+	t.Run("MergeConfig appends mixed content", func(t *testing.T) {
+		config := &Config{
+			Params:  types.Params{{Key: "limit", Value: []string{"10"}}},
+			Headers: types.Headers{{Key: "Authorization", Value: []string{"Bearer token1"}}},
+			Cookies: types.Cookies{{Key: "theme", Value: []string{"dark"}}},
+			Bodies:  types.Bodies{types.Body("original")},
+		}
+
+		newConfig := &Config{
+			Params:  types.Params{{Key: "offset", Value: []string{"0"}}, {Key: "limit", Value: []string{"20"}}},
+			Headers: types.Headers{{Key: "Content-Type", Value: []string{"application/json"}}, {Key: "Authorization", Value: []string{"Bearer token2"}}},
+			Cookies: types.Cookies{{Key: "lang", Value: []string{"en"}}, {Key: "theme", Value: []string{"light"}}},
+			Bodies:  types.Bodies{types.Body("updated")},
+		}
+
+		config.Merge(newConfig)
+
+		// Check params
+		assert.Len(t, config.Params, 2)
+		limitValue := config.Params.GetValue("limit")
+		require.NotNil(t, limitValue)
+		assert.Equal(t, []string{"10", "20"}, *limitValue)
+		offsetValue := config.Params.GetValue("offset")
+		require.NotNil(t, offsetValue)
+		assert.Equal(t, []string{"0"}, *offsetValue)
+
+		// Check headers
+		assert.Len(t, config.Headers, 2)
+		authValue := config.Headers.GetValue("Authorization")
+		require.NotNil(t, authValue)
+		assert.Equal(t, []string{"Bearer token1", "Bearer token2"}, *authValue)
+		contentTypeValue := config.Headers.GetValue("Content-Type")
+		require.NotNil(t, contentTypeValue)
+		assert.Equal(t, []string{"application/json"}, *contentTypeValue)
+
+		// Check cookies
+		assert.Len(t, config.Cookies, 2)
+		themeValue := config.Cookies.GetValue("theme")
+		require.NotNil(t, themeValue)
+		assert.Equal(t, []string{"dark", "light"}, *themeValue)
+		langValue := config.Cookies.GetValue("lang")
+		require.NotNil(t, langValue)
+		assert.Equal(t, []string{"en"}, *langValue)
+
+		// Check bodies
+		assert.Len(t, config.Bodies, 2)
+		assert.Equal(t, types.Body("original"), config.Bodies[0])
+		assert.Equal(t, types.Body("updated"), config.Bodies[1])
+	})
+
+	t.Run("MergeConfig with empty slices does not append", func(t *testing.T) {
+		config := &Config{
+			Params:  types.Params{{Key: "existing", Value: []string{"value"}}},
+			Headers: types.Headers{{Key: "Existing-Header", Value: []string{"value"}}},
+			Cookies: types.Cookies{{Key: "existing", Value: []string{"value"}}},
+			Bodies:  types.Bodies{types.Body("existing")},
+			Proxies: types.Proxies{},
+		}
+
+		originalParams := len(config.Params)
+		originalHeaders := len(config.Headers)
+		originalCookies := len(config.Cookies)
+		originalBodies := len(config.Bodies)
+		originalProxies := len(config.Proxies)
+
+		newConfig := &Config{
+			Params:  types.Params{},
+			Headers: types.Headers{},
+			Cookies: types.Cookies{},
+			Bodies:  types.Bodies{},
+			Proxies: types.Proxies{},
+		}
+
+		config.Merge(newConfig)
+
+		assert.Len(t, config.Params, originalParams, "Empty params should not change existing params")
+		assert.Len(t, config.Headers, originalHeaders, "Empty headers should not change existing headers")
+		assert.Len(t, config.Cookies, originalCookies, "Empty cookies should not change existing cookies")
+		assert.Len(t, config.Bodies, originalBodies, "Empty bodies should not change existing bodies")
+		assert.Len(t, config.Proxies, originalProxies, "Empty proxies should not change existing proxies")
+	})
+}

pkg/config/parser/base.go

@@ -0,0 +1,7 @@
+package parser
+
+import "github.com/aykhans/dodo/pkg/config"
+
+type IParser interface {
+	Parse() (*config.Config, error)
+}

pkg/config/parser/cli.go

@@ -1,4 +1,4 @@
-package config
+package parser
 
 import (
 	"errors"
@@ -8,6 +8,7 @@ import (
 	"strings"
 	"time"
 
+	"github.com/aykhans/dodo/pkg/config"
 	"github.com/aykhans/dodo/pkg/types"
 	"github.com/aykhans/dodo/pkg/utils"
 )
@@ -52,9 +53,10 @@ Flags:
   -x, -proxy        [string]  Proxy for the request (e.g. "http://proxy.example.com:8080")
   -skip-verify      bool      Skip SSL/TLS certificate verification (default %v)`
 
+var _ IParser = ConfigCLIParser{}
+
 type ConfigCLIParser struct {
 	args []string
-	configFile *types.ConfigFile
 }
 
 func NewConfigCLIParser(args []string) *ConfigCLIParser {
@@ -64,10 +66,6 @@ func NewConfigCLIParser(args []string) *ConfigCLIParser {
 	return &ConfigCLIParser{args: args}
 }
 
-func (parser ConfigCLIParser) GetConfigFile() *types.ConfigFile {
-	return parser.configFile
-}
-
 type stringSliceArg []string
 
 func (arg *stringSliceArg) String() string {
@@ -84,14 +82,14 @@ func (arg *stringSliceArg) Set(value string) error {
 // - types.ErrCLINoArgs
 // - types.CLIUnexpectedArgsError
 // - types.FieldParseErrors
-func (parser *ConfigCLIParser) Parse() (*Config, error) {
+func (parser ConfigCLIParser) Parse() (*config.Config, error) {
 	flagSet := flag.NewFlagSet("dodo", flag.ExitOnError)
 
 	flagSet.Usage = func() { parser.PrintHelp() }
 
 	var (
-		config       = &Config{}
+		config       = &config.Config{}
-		configFile   string
+		configFiles  = stringSliceArg{}
 		yes          bool
 		skipVerify   bool
 		method       string
@@ -108,8 +106,8 @@ func (parser *ConfigCLIParser) Parse() (*Config, error) {
 	)
 
 	{
-		flagSet.StringVar(&configFile, "config-file", "", "Config file")
+		flagSet.Var(&configFiles, "config-file", "Config file")
-		flagSet.StringVar(&configFile, "f", "", "Config file")
+		flagSet.Var(&configFiles, "f", "Config file")
 
 		flagSet.BoolVar(&yes, "yes", false, "Answer yes to all questions")
 		flagSet.BoolVar(&yes, "y", false, "Answer yes to all questions")
@@ -171,28 +169,50 @@ func (parser *ConfigCLIParser) Parse() (*Config, error) {
 	flagSet.Visit(func(flagVar *flag.Flag) {
 		switch flagVar.Name {
 		case "config-file", "f":
-			var err error
+			for i, configFile := range configFiles {
-			parser.configFile, err = types.ParseConfigFile(configFile)
+				configFileParsed, err := types.ParseConfigFile(configFile)
+
 				_ = utils.HandleErrorOrDie(err,
 					utils.OnSentinelError(types.ErrConfigFileExtensionNotFound, func(err error) error {
-					fieldParseErrors = append(fieldParseErrors, *types.NewFieldParseError("config-file", errors.New("file extension not found")))
+						fieldParseErrors = append(
+							fieldParseErrors,
+							*types.NewFieldParseError(
+								fmt.Sprintf("config-file[%d]", i),
+								configFile,
+								errors.New("file extension not found"),
+							),
+						)
 						return nil
 					}),
 					utils.OnCustomError(func(err types.RemoteConfigFileParseError) error {
-					fieldParseErrors = append(fieldParseErrors, *types.NewFieldParseError("config-file", fmt.Errorf("parse error: %w", err)))
+						fieldParseErrors = append(
+							fieldParseErrors,
+							*types.NewFieldParseError(
+								fmt.Sprintf("config-file[%d]", i),
+								configFile,
+								fmt.Errorf("parse error: %w", err),
+							),
+						)
 						return nil
 					}),
 					utils.OnCustomError(func(err types.UnknownConfigFileTypeError) error {
 						fieldParseErrors = append(
 							fieldParseErrors,
 							*types.NewFieldParseError(
-							"config-file",
+								fmt.Sprintf("config-file[%d]", i),
-							fmt.Errorf("file type '%s' not supported (supported types: %s)", err.Type, types.ConfigFileTypeYAML.String()),
+								configFile,
+								fmt.Errorf("file type '%s' not supported (supported types: %s)", err.Type, types.ConfigFileTypeYAML),
 							),
 						)
 						return nil
 					}),
 				)
+
+				if err == nil {
+					config.Files = append(config.Files, *configFileParsed)
+				}
+			}
+
 		case "yes", "y":
 			config.Yes = utils.ToPtr(yes)
 		case "skip-verify":
@@ -202,7 +222,7 @@ func (parser *ConfigCLIParser) Parse() (*Config, error) {
 		case "url", "u":
 			urlParsed, err := url.Parse(urlInput)
 			if err != nil {
-				fieldParseErrors = append(fieldParseErrors, *types.NewFieldParseError("url", err))
+				fieldParseErrors = append(fieldParseErrors, *types.NewFieldParseError("url", urlInput, err))
 			} else {
 				config.URL = urlParsed
 			}
@@ -228,7 +248,7 @@ func (parser *ConfigCLIParser) Parse() (*Config, error) {
 				if err != nil {
 					fieldParseErrors = append(
 						fieldParseErrors,
-						*types.NewFieldParseError(fmt.Sprintf("proxy[%d]", i), err),
+						*types.NewFieldParseError(fmt.Sprintf("proxy[%d]", i), proxy, err),
 					)
 				}
 			}
@@ -242,14 +262,14 @@ func (parser *ConfigCLIParser) Parse() (*Config, error) {
 	return config, nil
 }
 
-func (parser *ConfigCLIParser) PrintHelp() {
+func (parser ConfigCLIParser) PrintHelp() {
 	fmt.Printf(
 		cliUsageText+"\n",
-		Defaults.Yes,
+		config.Defaults.Yes,
-		Defaults.DodosCount,
+		config.Defaults.DodosCount,
-		Defaults.RequestTimeout,
+		config.Defaults.RequestTimeout,
-		Defaults.Method,
+		config.Defaults.Method,
-		Defaults.SkipVerify,
+		config.Defaults.SkipVerify,
 	)
 }
 

pkg/config/parser/cli_test.go

@@ -1,4 +1,4 @@
-package config
+package parser
 
 import (
 	"bytes"
@@ -8,6 +8,7 @@ import (
 	"testing"
 	"time"
 
+	"github.com/aykhans/dodo/pkg/config"
 	"github.com/aykhans/dodo/pkg/types"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
@@ -20,7 +21,6 @@ func TestNewConfigCLIParser(t *testing.T) {
 
 		require.NotNil(t, parser)
 		assert.Equal(t, args, parser.args)
-		assert.Nil(t, parser.configFile)
 	})
 
 	t.Run("NewConfigCLIParser with nil args", func(t *testing.T) {
@@ -28,7 +28,6 @@ func TestNewConfigCLIParser(t *testing.T) {
 
 		require.NotNil(t, parser)
 		assert.Equal(t, []string{}, parser.args)
-		assert.Nil(t, parser.configFile)
 	})
 
 	t.Run("NewConfigCLIParser with empty args", func(t *testing.T) {
@@ -37,21 +36,6 @@ func TestNewConfigCLIParser(t *testing.T) {
 
 		require.NotNil(t, parser)
 		assert.Equal(t, args, parser.args)
-		assert.Nil(t, parser.configFile)
-	})
-}
-
-func TestConfigCLIParser_GetConfigFile(t *testing.T) {
-	t.Run("GetConfigFile returns nil when no config file is set", func(t *testing.T) {
-		parser := NewConfigCLIParser([]string{"dodo"})
-		assert.Nil(t, parser.GetConfigFile())
-	})
-
-	t.Run("GetConfigFile returns config file when set", func(t *testing.T) {
-		parser := NewConfigCLIParser([]string{"dodo"})
-		expectedConfigFile := &types.ConfigFile{}
-		parser.configFile = expectedConfigFile
-		assert.Equal(t, expectedConfigFile, parser.GetConfigFile())
 	})
 }
 
@@ -130,6 +114,7 @@ func TestConfigCLIParser_Parse(t *testing.T) {
 		require.ErrorAs(t, err, &fieldErr)
 		assert.Len(t, fieldErr.Errors, 1)
 		assert.Equal(t, "url", fieldErr.Errors[0].Field)
+		assert.Equal(t, "://invalid-url", fieldErr.Errors[0].Value)
 	})
 
 	t.Run("Parse with method flag", func(t *testing.T) {
@@ -272,6 +257,7 @@ func TestConfigCLIParser_Parse(t *testing.T) {
 		require.ErrorAs(t, err, &fieldErr)
 		assert.Len(t, fieldErr.Errors, 1)
 		assert.Equal(t, "proxy[0]", fieldErr.Errors[0].Field)
+		assert.Equal(t, "://invalid-proxy", fieldErr.Errors[0].Value)
 	})
 
 	t.Run("Parse with mixed valid and invalid proxies", func(t *testing.T) {
@@ -283,6 +269,7 @@ func TestConfigCLIParser_Parse(t *testing.T) {
 		require.ErrorAs(t, err, &fieldErr)
 		assert.Len(t, fieldErr.Errors, 1)
 		assert.Equal(t, "proxy[1]", fieldErr.Errors[0].Field)
+		assert.Equal(t, "://invalid", fieldErr.Errors[0].Value)
 	})
 
 	t.Run("Parse with long flag names", func(t *testing.T) {
@@ -318,7 +305,7 @@ func TestConfigCLIParser_Parse(t *testing.T) {
 
 		require.NoError(t, err)
 		require.NotNil(t, config)
-		assert.NotNil(t, parser.GetConfigFile())
+		assert.Len(t, config.Files, 1)
 	})
 
 	t.Run("Parse with config-file flag using long form", func(t *testing.T) {
@@ -327,7 +314,7 @@ func TestConfigCLIParser_Parse(t *testing.T) {
 
 		require.NoError(t, err)
 		require.NotNil(t, config)
-		assert.NotNil(t, parser.GetConfigFile())
+		assert.Len(t, config.Files, 1)
 	})
 
 	t.Run("Parse with config-file flag invalid extension", func(t *testing.T) {
@@ -338,7 +325,8 @@ func TestConfigCLIParser_Parse(t *testing.T) {
 		var fieldErr types.FieldParseErrors
 		require.ErrorAs(t, err, &fieldErr)
 		assert.Len(t, fieldErr.Errors, 1)
-		assert.Equal(t, "config-file", fieldErr.Errors[0].Field)
+		assert.Equal(t, "config-file[0]", fieldErr.Errors[0].Field)
+		assert.Equal(t, "/path/to/config", fieldErr.Errors[0].Value)
 		assert.Contains(t, fieldErr.Errors[0].Err.Error(), "file extension not found")
 	})
 
@@ -350,7 +338,8 @@ func TestConfigCLIParser_Parse(t *testing.T) {
 		var fieldErr types.FieldParseErrors
 		require.ErrorAs(t, err, &fieldErr)
 		assert.Len(t, fieldErr.Errors, 1)
-		assert.Equal(t, "config-file", fieldErr.Errors[0].Field)
+		assert.Equal(t, "config-file[0]", fieldErr.Errors[0].Field)
+		assert.Equal(t, "/path/to/config.json", fieldErr.Errors[0].Value)
 		assert.Contains(t, fieldErr.Errors[0].Err.Error(), "file type")
 		assert.Contains(t, fieldErr.Errors[0].Err.Error(), "not supported")
 	})
@@ -361,7 +350,16 @@ func TestConfigCLIParser_Parse(t *testing.T) {
 
 		require.NoError(t, err)
 		require.NotNil(t, config)
-		assert.NotNil(t, parser.GetConfigFile())
+		assert.Len(t, config.Files, 1)
+	})
+
+	t.Run("Parse with multiple config files", func(t *testing.T) {
+		parser := NewConfigCLIParser([]string{"dodo", "-f", "/path/config1.yaml", "-f", "/path/config2.yml"})
+		config, err := parser.Parse()
+
+		require.NoError(t, err)
+		require.NotNil(t, config)
+		assert.Len(t, config.Files, 2)
 	})
 
 	t.Run("Parse with all flags combined", func(t *testing.T) {
@@ -412,7 +410,7 @@ func TestConfigCLIParser_Parse(t *testing.T) {
 		assert.Len(t, config.Proxies, 1)
 		assert.Equal(t, "http://proxy.example.com:3128", config.Proxies[0].String())
 
-		assert.NotNil(t, parser.GetConfigFile())
+		assert.Len(t, config.Files, 1)
 	})
 
 	t.Run("Parse with multiple field parse errors", func(t *testing.T) {
@@ -437,6 +435,15 @@ func TestConfigCLIParser_Parse(t *testing.T) {
 		assert.True(t, fields["url"])
 		assert.True(t, fields["proxy[0]"])
 		assert.True(t, fields["proxy[1]"])
+
+		// Check error values
+		values := make(map[string]string)
+		for _, parseErr := range fieldErr.Errors {
+			values[parseErr.Field] = parseErr.Value
+		}
+		assert.Equal(t, "://invalid-url", values["url"])
+		assert.Equal(t, "://invalid-proxy1", values["proxy[0]"])
+		assert.Equal(t, "://invalid-proxy2", values["proxy[1]"])
 	})
 }
 
@@ -479,7 +486,7 @@ func TestConfigCLIParser_PrintHelp(t *testing.T) {
 		assert.Contains(t, output, "-f, -config-file")
 
 		// Verify default values are included
-		assert.Contains(t, output, Defaults.Method)
+		assert.Contains(t, output, config.Defaults.Method)
 		assert.Contains(t, output, "1")     // DodosCount default
 		assert.Contains(t, output, "10s")   // RequestTimeout default
 		assert.Contains(t, output, "false") // Yes default

pkg/config/parser/env.go

@@ -0,0 +1,236 @@
+package parser
+
+import (
+	"errors"
+	"fmt"
+	"net/url"
+	"os"
+	"time"
+
+	"github.com/aykhans/dodo/pkg/config"
+	"github.com/aykhans/dodo/pkg/types"
+	"github.com/aykhans/dodo/pkg/utils"
+)
+
+var _ IParser = ConfigENVParser{}
+
+type ConfigENVParser struct {
+	envPrefix string
+}
+
+func NewConfigENVParser(envPrefix string) *ConfigENVParser {
+	return &ConfigENVParser{envPrefix}
+}
+
+// Parse parses env arguments into a Config object.
+// It can return the following errors:
+// - types.FieldParseErrors
+func (parser ConfigENVParser) Parse() (*config.Config, error) {
+	var (
+		config           = &config.Config{}
+		fieldParseErrors []types.FieldParseError
+	)
+
+	if configFile := parser.getEnv("CONFIG_FILE"); configFile != "" {
+		configFileParsed, err := types.ParseConfigFile(configFile)
+
+		_ = utils.HandleErrorOrDie(err,
+			utils.OnSentinelError(types.ErrConfigFileExtensionNotFound, func(err error) error {
+				fieldParseErrors = append(
+					fieldParseErrors,
+					*types.NewFieldParseError(
+						parser.getFullEnvName("CONFIG_FILE"),
+						configFile,
+						errors.New("file extension not found"),
+					),
+				)
+				return nil
+			}),
+			utils.OnCustomError(func(err types.RemoteConfigFileParseError) error {
+				fieldParseErrors = append(
+					fieldParseErrors,
+					*types.NewFieldParseError(
+						parser.getFullEnvName("CONFIG_FILE"),
+						configFile,
+						fmt.Errorf("parse error: %w", err),
+					),
+				)
+				return nil
+			}),
+			utils.OnCustomError(func(err types.UnknownConfigFileTypeError) error {
+				fieldParseErrors = append(
+					fieldParseErrors,
+					*types.NewFieldParseError(
+						parser.getFullEnvName("CONFIG_FILE"),
+						configFile,
+						fmt.Errorf("file type '%s' not supported (supported types: %s)", err.Type, types.ConfigFileTypeYAML),
+					),
+				)
+				return nil
+			}),
+		)
+
+		if err == nil {
+			config.Files = append(config.Files, *configFileParsed)
+		}
+	}
+
+	if yes := parser.getEnv("YES"); yes != "" {
+		yesParsed, err := utils.ParseString[bool](yes)
+		if err != nil {
+			fieldParseErrors = append(
+				fieldParseErrors,
+				*types.NewFieldParseError(
+					parser.getFullEnvName("YES"),
+					yes,
+					errors.New("invalid value for boolean, expected 'true' or 'false'"),
+				),
+			)
+		} else {
+			config.Yes = &yesParsed
+		}
+	}
+
+	if skipVerify := parser.getEnv("SKIP_VERIFY"); skipVerify != "" {
+		skipVerifyParsed, err := utils.ParseString[bool](skipVerify)
+		if err != nil {
+			fieldParseErrors = append(
+				fieldParseErrors,
+				*types.NewFieldParseError(
+					parser.getFullEnvName("SKIP_VERIFY"),
+					skipVerify,
+					errors.New("invalid value for boolean, expected 'true' or 'false'"),
+				),
+			)
+		} else {
+			config.SkipVerify = &skipVerifyParsed
+		}
+	}
+
+	if method := parser.getEnv("METHOD"); method != "" {
+		config.Method = &method
+	}
+
+	if urlEnv := parser.getEnv("URL"); urlEnv != "" {
+		urlEnvParsed, err := url.Parse(urlEnv)
+		if err != nil {
+			fieldParseErrors = append(
+				fieldParseErrors,
+				*types.NewFieldParseError(parser.getFullEnvName("URL"), urlEnv, err),
+			)
+		} else {
+			config.URL = urlEnvParsed
+		}
+	}
+
+	if dodos := parser.getEnv("DODOS"); dodos != "" {
+		dodosParsed, err := utils.ParseString[uint](dodos)
+		if err != nil {
+			fieldParseErrors = append(
+				fieldParseErrors,
+				*types.NewFieldParseError(
+					parser.getFullEnvName("DODOS"),
+					dodos,
+					errors.New("invalid value for unsigned integer"),
+				),
+			)
+		} else {
+			config.DodosCount = &dodosParsed
+		}
+	}
+
+	if requests := parser.getEnv("REQUESTS"); requests != "" {
+		requestsParsed, err := utils.ParseString[uint](requests)
+		if err != nil {
+			fieldParseErrors = append(
+				fieldParseErrors,
+				*types.NewFieldParseError(
+					parser.getFullEnvName("REQUESTS"),
+					requests,
+					errors.New("invalid value for unsigned integer"),
+				),
+			)
+		} else {
+			config.RequestCount = &requestsParsed
+		}
+	}
+
+	if duration := parser.getEnv("DURATION"); duration != "" {
+		durationParsed, err := utils.ParseString[time.Duration](duration)
+		if err != nil {
+			fieldParseErrors = append(
+				fieldParseErrors,
+				*types.NewFieldParseError(
+					parser.getFullEnvName("DURATION"),
+					duration,
+					errors.New("invalid value duration, expected a duration string (e.g., '10s', '1h30m')"),
+				),
+			)
+		} else {
+			config.Duration = &durationParsed
+		}
+	}
+
+	if timeout := parser.getEnv("TIMEOUT"); timeout != "" {
+		timeoutParsed, err := utils.ParseString[time.Duration](timeout)
+		if err != nil {
+			fieldParseErrors = append(
+				fieldParseErrors,
+				*types.NewFieldParseError(
+					parser.getFullEnvName("TIMEOUT"),
+					timeout,
+					errors.New("invalid value duration, expected a duration string (e.g., '10s', '1h30m')"),
+				),
+			)
+		} else {
+			config.Timeout = &timeoutParsed
+		}
+	}
+
+	if param := parser.getEnv("PARAM"); param != "" {
+		config.Params.Parse(param)
+	}
+
+	if header := parser.getEnv("HEADER"); header != "" {
+		config.Headers.Parse(header)
+	}
+
+	if cookie := parser.getEnv("COOKIE"); cookie != "" {
+		config.Cookies.Parse(cookie)
+	}
+
+	if body := parser.getEnv("BODY"); body != "" {
+		config.Bodies.Parse(body)
+	}
+
+	if proxy := parser.getEnv("PROXY"); proxy != "" {
+		err := config.Proxies.Parse(proxy)
+		if err != nil {
+			fieldParseErrors = append(
+				fieldParseErrors,
+				*types.NewFieldParseError(
+					parser.getFullEnvName("PROXY"),
+					proxy,
+					err,
+				),
+			)
+		}
+	}
+
+	if len(fieldParseErrors) > 0 {
+		return nil, types.NewFieldParseErrors(fieldParseErrors)
+	}
+
+	return config, nil
+}
+
+func (parser ConfigENVParser) getFullEnvName(envName string) string {
+	if parser.envPrefix == "" {
+		return envName
+	}
+	return parser.envPrefix + "_" + envName
+}
+
+func (parser ConfigENVParser) getEnv(envName string) string {
+	return os.Getenv(parser.getFullEnvName(envName))
+}

pkg/types/body.go

@@ -8,8 +8,8 @@ func (body Body) String() string {
 
 type Bodies []Body
 
-func (bodies *Bodies) Append(body Body) {
+func (bodies *Bodies) Append(body ...Body) {
-	*bodies = append(*bodies, body)
+	*bodies = append(*bodies, body...)
 }
 
 func (bodies *Bodies) Parse(rawValues ...string) {

pkg/types/body_test.go

@@ -49,6 +49,16 @@ func TestBodies_Append(t *testing.T) {
 		assert.Equal(t, Body("third"), (*bodies)[2])
 	})
 
+	t.Run("Append multiple bodies in single call", func(t *testing.T) {
+		bodies := &Bodies{}
+		bodies.Append(Body("first"), Body("second"), Body("third"))
+
+		assert.Len(t, *bodies, 3)
+		assert.Equal(t, Body("first"), (*bodies)[0])
+		assert.Equal(t, Body("second"), (*bodies)[1])
+		assert.Equal(t, Body("third"), (*bodies)[2])
+	})
+
 	t.Run("Append to existing bodies", func(t *testing.T) {
 		bodies := &Bodies{Body("existing")}
 		bodies.Append(Body("new"))
@@ -58,6 +68,17 @@ func TestBodies_Append(t *testing.T) {
 		assert.Equal(t, Body("new"), (*bodies)[1])
 	})
 
+	t.Run("Append multiple to existing bodies", func(t *testing.T) {
+		bodies := &Bodies{Body("existing")}
+		bodies.Append(Body("new1"), Body("new2"), Body("new3"))
+
+		assert.Len(t, *bodies, 4)
+		assert.Equal(t, Body("existing"), (*bodies)[0])
+		assert.Equal(t, Body("new1"), (*bodies)[1])
+		assert.Equal(t, Body("new2"), (*bodies)[2])
+		assert.Equal(t, Body("new3"), (*bodies)[3])
+	})
+
 	t.Run("Append empty body", func(t *testing.T) {
 		bodies := &Bodies{}
 		bodies.Append(Body(""))
@@ -65,6 +86,29 @@ func TestBodies_Append(t *testing.T) {
 		assert.Len(t, *bodies, 1)
 		assert.Empty(t, (*bodies)[0].String())
 	})
+
+	t.Run("Append no bodies", func(t *testing.T) {
+		bodies := &Bodies{Body("existing")}
+		bodies.Append()
+
+		assert.Len(t, *bodies, 1)
+		assert.Equal(t, Body("existing"), (*bodies)[0])
+	})
+
+	t.Run("Append mixed bodies", func(t *testing.T) {
+		bodies := &Bodies{}
+		bodies.Append(Body("first"), Body(""))
+		bodies.Append(Body("second"))
+		bodies.Append(Body("third"), Body("fourth"), Body("fifth"))
+
+		assert.Len(t, *bodies, 6)
+		assert.Equal(t, Body("first"), (*bodies)[0])
+		assert.Equal(t, Body(""), (*bodies)[1])
+		assert.Equal(t, Body("second"), (*bodies)[2])
+		assert.Equal(t, Body("third"), (*bodies)[3])
+		assert.Equal(t, Body("fourth"), (*bodies)[4])
+		assert.Equal(t, Body("fifth"), (*bodies)[5])
+	})
 }
 
 func TestBodies_Parse(t *testing.T) {

pkg/types/config_file.go

@@ -6,39 +6,19 @@ import (
 	"strings"
 )
 
-type ConfigFileType int
+type ConfigFileType string
 
 const (
-	ConfigFileTypeYAML ConfigFileType = iota
+	ConfigFileTypeYAML ConfigFileType = "yaml/yml"
 )
 
-func (t ConfigFileType) String() string {
+type ConfigFileLocationType string
-	switch t {
-	case ConfigFileTypeYAML:
-		return "yaml/yml"
-	default:
-		return "unknown"
-	}
-}
-
-type ConfigFileLocationType int
 
 const (
-	ConfigFileLocationLocal ConfigFileLocationType = iota
+	ConfigFileLocationLocal  ConfigFileLocationType = "local"
-	ConfigFileLocationRemote
+	ConfigFileLocationRemote ConfigFileLocationType = "remote"
 )
 
-func (l ConfigFileLocationType) String() string {
-	switch l {
-	case ConfigFileLocationLocal:
-		return "local"
-	case ConfigFileLocationRemote:
-		return "remote"
-	default:
-		return "unknown"
-	}
-}
-
 type ConfigFile struct {
 	path         string
 	_type        ConfigFileType

pkg/types/config_file_test.go

@@ -7,35 +7,6 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
-func TestConfigFileType_String(t *testing.T) {
-	t.Run("ConfigFileTypeYAML returns yaml", func(t *testing.T) {
-		configType := ConfigFileTypeYAML
-		assert.Equal(t, "yaml/yml", configType.String())
-	})
-
-	t.Run("Unknown config file type returns unknown", func(t *testing.T) {
-		configType := ConfigFileType(999)
-		assert.Equal(t, "unknown", configType.String())
-	})
-}
-
-func TestConfigFileLocationType_String(t *testing.T) {
-	t.Run("ConfigFileLocationLocal returns local", func(t *testing.T) {
-		locationType := ConfigFileLocationLocal
-		assert.Equal(t, "local", locationType.String())
-	})
-
-	t.Run("ConfigFileLocationRemote returns remote", func(t *testing.T) {
-		locationType := ConfigFileLocationRemote
-		assert.Equal(t, "remote", locationType.String())
-	})
-
-	t.Run("Unknown location type returns unknown", func(t *testing.T) {
-		locationType := ConfigFileLocationType(999)
-		assert.Equal(t, "unknown", locationType.String())
-	})
-}
-
 func TestConfigFile_String(t *testing.T) {
 	t.Run("String returns the file path", func(t *testing.T) {
 		configFile := ConfigFile{path: "/path/to/config.yaml"}

pkg/types/cookie.go

@@ -15,11 +15,13 @@ func (cookies Cookies) GetValue(key string) *[]string {
 	return nil
 }
 
-func (cookies *Cookies) Append(cookie Cookie) {
+func (cookies *Cookies) Append(cookie ...Cookie) {
-	if item := cookies.GetValue(cookie.Key); item != nil {
+	for _, c := range cookie {
-		*item = append(*item, cookie.Value...)
+		if item := cookies.GetValue(c.Key); item != nil {
+			*item = append(*item, c.Value...)
 		} else {
-		*cookies = append(*cookies, cookie)
+			*cookies = append(*cookies, c)
+		}
 	}
 }
 

pkg/types/cookie_test.go

@@ -88,6 +88,39 @@ func TestCookies_Append(t *testing.T) {
 		assert.Len(t, *cookies, 3)
 	})
 
+	t.Run("Append multiple cookies in single call", func(t *testing.T) {
+		cookies := &Cookies{}
+		cookies.Append(
+			Cookie{Key: "session", Value: []string{"abc123"}},
+			Cookie{Key: "user", Value: []string{"john"}},
+			Cookie{Key: "token", Value: []string{"xyz789"}},
+		)
+
+		assert.Len(t, *cookies, 3)
+		assert.Equal(t, "session", (*cookies)[0].Key)
+		assert.Equal(t, []string{"abc123"}, (*cookies)[0].Value)
+		assert.Equal(t, "user", (*cookies)[1].Key)
+		assert.Equal(t, []string{"john"}, (*cookies)[1].Value)
+		assert.Equal(t, "token", (*cookies)[2].Key)
+		assert.Equal(t, []string{"xyz789"}, (*cookies)[2].Value)
+	})
+
+	t.Run("Append multiple with existing keys", func(t *testing.T) {
+		cookies := &Cookies{
+			{Key: "prefs", Value: []string{"theme=dark"}},
+		}
+		cookies.Append(
+			Cookie{Key: "prefs", Value: []string{"lang=en"}},
+			Cookie{Key: "prefs", Value: []string{"tz=UTC"}},
+			Cookie{Key: "session", Value: []string{"abc123"}},
+		)
+
+		assert.Len(t, *cookies, 2)
+		assert.Equal(t, []string{"theme=dark", "lang=en", "tz=UTC"}, (*cookies)[0].Value)
+		assert.Equal(t, "session", (*cookies)[1].Key)
+		assert.Equal(t, []string{"abc123"}, (*cookies)[1].Value)
+	})
+
 	t.Run("Append multiple values at once", func(t *testing.T) {
 		cookies := &Cookies{
 			{Key: "tags", Value: []string{"tag1"}},
@@ -105,6 +138,88 @@ func TestCookies_Append(t *testing.T) {
 		assert.Len(t, *cookies, 1)
 		assert.Equal(t, []string{""}, (*cookies)[0].Value)
 	})
+
+	t.Run("Append no cookies", func(t *testing.T) {
+		cookies := &Cookies{
+			{Key: "existing", Value: []string{"value"}},
+		}
+		cookies.Append()
+
+		assert.Len(t, *cookies, 1)
+		assert.Equal(t, "existing", (*cookies)[0].Key)
+		assert.Equal(t, []string{"value"}, (*cookies)[0].Value)
+	})
+
+	t.Run("Append mixed new and existing cookies", func(t *testing.T) {
+		cookies := &Cookies{
+			{Key: "session", Value: []string{"old_session"}},
+			{Key: "theme", Value: []string{"dark"}},
+		}
+		cookies.Append(
+			Cookie{Key: "session", Value: []string{"new_session"}},
+			Cookie{Key: "user", Value: []string{"john"}},
+			Cookie{Key: "theme", Value: []string{"light"}},
+			Cookie{Key: "lang", Value: []string{"en"}},
+		)
+
+		assert.Len(t, *cookies, 4)
+
+		sessionValue := cookies.GetValue("session")
+		require.NotNil(t, sessionValue)
+		assert.Equal(t, []string{"old_session", "new_session"}, *sessionValue)
+
+		themeValue := cookies.GetValue("theme")
+		require.NotNil(t, themeValue)
+		assert.Equal(t, []string{"dark", "light"}, *themeValue)
+
+		userValue := cookies.GetValue("user")
+		require.NotNil(t, userValue)
+		assert.Equal(t, []string{"john"}, *userValue)
+
+		langValue := cookies.GetValue("lang")
+		require.NotNil(t, langValue)
+		assert.Equal(t, []string{"en"}, *langValue)
+	})
+
+	t.Run("Append cookies with multiple values", func(t *testing.T) {
+		cookies := &Cookies{}
+		cookies.Append(
+			Cookie{Key: "permissions", Value: []string{"read", "write", "delete"}},
+			Cookie{Key: "features", Value: []string{"advanced", "beta"}},
+		)
+
+		assert.Len(t, *cookies, 2)
+		assert.Equal(t, []string{"read", "write", "delete"}, (*cookies)[0].Value)
+		assert.Equal(t, []string{"advanced", "beta"}, (*cookies)[1].Value)
+	})
+
+	t.Run("Append typical session cookies", func(t *testing.T) {
+		cookies := &Cookies{}
+		cookies.Append(
+			Cookie{Key: "JSESSIONID", Value: []string{"A1B2C3D4E5F6"}},
+			Cookie{Key: "PHPSESSID", Value: []string{"abcdef123456"}},
+			Cookie{Key: "session_token", Value: []string{"eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9"}},
+			Cookie{Key: "__Secure-next-auth.session-token", Value: []string{"secure_token_123"}},
+		)
+
+		assert.Len(t, *cookies, 4)
+
+		jsessionValue := cookies.GetValue("JSESSIONID")
+		require.NotNil(t, jsessionValue)
+		assert.Equal(t, []string{"A1B2C3D4E5F6"}, *jsessionValue)
+
+		phpValue := cookies.GetValue("PHPSESSID")
+		require.NotNil(t, phpValue)
+		assert.Equal(t, []string{"abcdef123456"}, *phpValue)
+
+		sessionValue := cookies.GetValue("session_token")
+		require.NotNil(t, sessionValue)
+		assert.Equal(t, []string{"eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9"}, *sessionValue)
+
+		secureValue := cookies.GetValue("__Secure-next-auth.session-token")
+		require.NotNil(t, secureValue)
+		assert.Equal(t, []string{"secure_token_123"}, *secureValue)
+	})
 }
 
 func TestCookies_Parse(t *testing.T) {

pkg/types/errors.go

@@ -22,14 +22,15 @@ var (
 
 type FieldParseError struct {
 	Field string
+	Value string
 	Err   error
 }
 
-func NewFieldParseError(field string, err error) *FieldParseError {
+func NewFieldParseError(field string, value string, err error) *FieldParseError {
 	if err == nil {
 		err = ErrNoError
 	}
-	return &FieldParseError{field, err}
+	return &FieldParseError{field, value, err}
 }
 
 func (e FieldParseError) Error() string {

pkg/types/errors_test.go

@@ -10,7 +10,7 @@ import (
 func TestFieldParseError_Error(t *testing.T) {
 	t.Run("Error returns formatted message", func(t *testing.T) {
 		originalErr := errors.New("invalid value")
-		fieldErr := NewFieldParseError("username", originalErr)
+		fieldErr := NewFieldParseError("username", "testuser", originalErr)
 
 		expected := "Field 'username' parse failed: invalid value"
 		assert.Equal(t, expected, fieldErr.Error())
@@ -18,14 +18,14 @@ func TestFieldParseError_Error(t *testing.T) {
 
 	t.Run("Error with empty field name", func(t *testing.T) {
 		originalErr := errors.New("test error")
-		fieldErr := NewFieldParseError("", originalErr)
+		fieldErr := NewFieldParseError("", "somevalue", originalErr)
 
 		expected := "Field '' parse failed: test error"
 		assert.Equal(t, expected, fieldErr.Error())
 	})
 
 	t.Run("Error with nil underlying error", func(t *testing.T) {
-		fieldErr := NewFieldParseError("field", nil)
+		fieldErr := NewFieldParseError("field", "value123", nil)
 
 		expected := "Field 'field' parse failed: no error (internal)"
 		assert.Equal(t, expected, fieldErr.Error())
@@ -35,13 +35,13 @@ func TestFieldParseError_Error(t *testing.T) {
 func TestFieldParseError_Unwrap(t *testing.T) {
 	t.Run("Unwrap returns original error", func(t *testing.T) {
 		originalErr := errors.New("original error")
-		fieldErr := NewFieldParseError("field", originalErr)
+		fieldErr := NewFieldParseError("field", "value", originalErr)
 
 		assert.Equal(t, originalErr, fieldErr.Unwrap())
 	})
 
 	t.Run("Unwrap with nil error", func(t *testing.T) {
-		fieldErr := NewFieldParseError("field", nil)
+		fieldErr := NewFieldParseError("field", "value", nil)
 
 		assert.Equal(t, ErrNoError, fieldErr.Unwrap())
 	})
@@ -50,16 +50,18 @@ func TestFieldParseError_Unwrap(t *testing.T) {
 func TestNewFieldParseError(t *testing.T) {
 	t.Run("Creates FieldParseError with correct values", func(t *testing.T) {
 		originalErr := errors.New("test error")
-		fieldErr := NewFieldParseError("testField", originalErr)
+		fieldErr := NewFieldParseError("testField", "testValue", originalErr)
 
 		assert.Equal(t, "testField", fieldErr.Field)
+		assert.Equal(t, "testValue", fieldErr.Value)
 		assert.Equal(t, originalErr, fieldErr.Err)
 	})
 
 	t.Run("Creates FieldParseError with ErrNoError when nil passed", func(t *testing.T) {
-		fieldErr := NewFieldParseError("testField", nil)
+		fieldErr := NewFieldParseError("testField", "testValue", nil)
 
 		assert.Equal(t, "testField", fieldErr.Field)
+		assert.Equal(t, "testValue", fieldErr.Value)
 		assert.Equal(t, ErrNoError, fieldErr.Err)
 	})
 }
@@ -72,7 +74,7 @@ func TestFieldParseErrors_Error(t *testing.T) {
 	})
 
 	t.Run("Error with single error returns single error message", func(t *testing.T) {
-		fieldErr := *NewFieldParseError("field1", errors.New("error1"))
+		fieldErr := *NewFieldParseError("field1", "value1", errors.New("error1"))
 		fieldErrors := NewFieldParseErrors([]FieldParseError{fieldErr})
 
 		expected := "Field 'field1' parse failed: error1"
@@ -80,9 +82,9 @@ func TestFieldParseErrors_Error(t *testing.T) {
 	})
 
 	t.Run("Error with multiple errors returns concatenated messages", func(t *testing.T) {
-		fieldErr1 := *NewFieldParseError("field1", errors.New("error1"))
+		fieldErr1 := *NewFieldParseError("field1", "value1", errors.New("error1"))
-		fieldErr2 := *NewFieldParseError("field2", errors.New("error2"))
+		fieldErr2 := *NewFieldParseError("field2", "value2", errors.New("error2"))
-		fieldErr3 := *NewFieldParseError("field3", errors.New("error3"))
+		fieldErr3 := *NewFieldParseError("field3", "value3", errors.New("error3"))
 		fieldErrors := NewFieldParseErrors([]FieldParseError{fieldErr1, fieldErr2, fieldErr3})
 
 		expected := "Field 'field1' parse failed: error1\nField 'field2' parse failed: error2\nField 'field3' parse failed: error3"
@@ -90,8 +92,8 @@ func TestFieldParseErrors_Error(t *testing.T) {
 	})
 
 	t.Run("Error with two errors", func(t *testing.T) {
-		fieldErr1 := *NewFieldParseError("username", errors.New("too short"))
+		fieldErr1 := *NewFieldParseError("username", "john", errors.New("too short"))
-		fieldErr2 := *NewFieldParseError("email", errors.New("invalid format"))
+		fieldErr2 := *NewFieldParseError("email", "invalid", errors.New("invalid format"))
 		fieldErrors := NewFieldParseErrors([]FieldParseError{fieldErr1, fieldErr2})
 
 		expected := "Field 'username' parse failed: too short\nField 'email' parse failed: invalid format"
@@ -101,8 +103,8 @@ func TestFieldParseErrors_Error(t *testing.T) {
 
 func TestNewFieldParseErrors(t *testing.T) {
 	t.Run("Creates FieldParseErrors with correct values", func(t *testing.T) {
-		fieldErr1 := *NewFieldParseError("field1", errors.New("error1"))
+		fieldErr1 := *NewFieldParseError("field1", "value1", errors.New("error1"))
-		fieldErr2 := *NewFieldParseError("field2", errors.New("error2"))
+		fieldErr2 := *NewFieldParseError("field2", "value2", errors.New("error2"))
 		fieldErrors := NewFieldParseErrors([]FieldParseError{fieldErr1, fieldErr2})
 
 		assert.Len(t, fieldErrors.Errors, 2)
@@ -258,7 +260,7 @@ func TestErrorConstants(t *testing.T) {
 
 func TestErrorImplementsErrorInterface(t *testing.T) {
 	t.Run("FieldParseError implements error interface", func(t *testing.T) {
-		var err error = NewFieldParseError("field", errors.New("test"))
+		var err error = NewFieldParseError("field", "value", errors.New("test"))
 		assert.Error(t, err)
 	})
 

pkg/types/header.go

@@ -25,11 +25,13 @@ func (headers Headers) GetValue(key string) *[]string {
 	return nil
 }
 
-func (headers *Headers) Append(header Header) {
+func (headers *Headers) Append(header ...Header) {
-	if item := headers.GetValue(header.Key); item != nil {
+	for _, h := range header {
-		*item = append(*item, header.Value...)
+		if item := headers.GetValue(h.Key); item != nil {
+			*item = append(*item, h.Value...)
 		} else {
-		*headers = append(*headers, header)
+			*headers = append(*headers, h)
+		}
 	}
 }
 

pkg/types/header_test.go

@@ -125,6 +125,39 @@ func TestHeaders_Append(t *testing.T) {
 		assert.Len(t, *headers, 3)
 	})
 
+	t.Run("Append multiple headers in single call", func(t *testing.T) {
+		headers := &Headers{}
+		headers.Append(
+			Header{Key: "Content-Type", Value: []string{"application/json"}},
+			Header{Key: "Authorization", Value: []string{"Bearer token"}},
+			Header{Key: "Accept", Value: []string{"*/*"}},
+		)
+
+		assert.Len(t, *headers, 3)
+		assert.Equal(t, "Content-Type", (*headers)[0].Key)
+		assert.Equal(t, []string{"application/json"}, (*headers)[0].Value)
+		assert.Equal(t, "Authorization", (*headers)[1].Key)
+		assert.Equal(t, []string{"Bearer token"}, (*headers)[1].Value)
+		assert.Equal(t, "Accept", (*headers)[2].Key)
+		assert.Equal(t, []string{"*/*"}, (*headers)[2].Value)
+	})
+
+	t.Run("Append multiple with existing keys", func(t *testing.T) {
+		headers := &Headers{
+			{Key: "Accept", Value: []string{"text/html"}},
+		}
+		headers.Append(
+			Header{Key: "Accept", Value: []string{"application/json"}},
+			Header{Key: "Accept", Value: []string{"application/xml"}},
+			Header{Key: "Content-Type", Value: []string{"text/plain"}},
+		)
+
+		assert.Len(t, *headers, 2)
+		assert.Equal(t, []string{"text/html", "application/json", "application/xml"}, (*headers)[0].Value)
+		assert.Equal(t, "Content-Type", (*headers)[1].Key)
+		assert.Equal(t, []string{"text/plain"}, (*headers)[1].Value)
+	})
+
 	t.Run("Append multiple values at once", func(t *testing.T) {
 		headers := &Headers{
 			{Key: "Accept-Language", Value: []string{"en"}},
@@ -142,6 +175,78 @@ func TestHeaders_Append(t *testing.T) {
 		assert.Len(t, *headers, 1)
 		assert.Equal(t, []string{""}, (*headers)[0].Value)
 	})
+
+	t.Run("Append no headers", func(t *testing.T) {
+		headers := &Headers{
+			{Key: "Existing", Value: []string{"value"}},
+		}
+		headers.Append()
+
+		assert.Len(t, *headers, 1)
+		assert.Equal(t, "Existing", (*headers)[0].Key)
+		assert.Equal(t, []string{"value"}, (*headers)[0].Value)
+	})
+
+	t.Run("Append mixed new and existing headers", func(t *testing.T) {
+		headers := &Headers{
+			{Key: "Cache-Control", Value: []string{"no-cache"}},
+			{Key: "Accept", Value: []string{"text/html"}},
+		}
+		headers.Append(
+			Header{Key: "Cache-Control", Value: []string{"no-store"}},
+			Header{Key: "User-Agent", Value: []string{"Mozilla/5.0"}},
+			Header{Key: "Accept", Value: []string{"application/json"}},
+			Header{Key: "X-Custom", Value: []string{"custom-value"}},
+		)
+
+		assert.Len(t, *headers, 4)
+
+		cacheValue := headers.GetValue("Cache-Control")
+		require.NotNil(t, cacheValue)
+		assert.Equal(t, []string{"no-cache", "no-store"}, *cacheValue)
+
+		acceptValue := headers.GetValue("Accept")
+		require.NotNil(t, acceptValue)
+		assert.Equal(t, []string{"text/html", "application/json"}, *acceptValue)
+
+		userAgentValue := headers.GetValue("User-Agent")
+		require.NotNil(t, userAgentValue)
+		assert.Equal(t, []string{"Mozilla/5.0"}, *userAgentValue)
+
+		customValue := headers.GetValue("X-Custom")
+		require.NotNil(t, customValue)
+		assert.Equal(t, []string{"custom-value"}, *customValue)
+	})
+
+	t.Run("Append headers with multiple values", func(t *testing.T) {
+		headers := &Headers{}
+		headers.Append(
+			Header{Key: "Accept", Value: []string{"text/html", "application/json", "application/xml"}},
+			Header{Key: "Accept-Encoding", Value: []string{"gzip", "deflate"}},
+		)
+
+		assert.Len(t, *headers, 2)
+		assert.Equal(t, []string{"text/html", "application/json", "application/xml"}, (*headers)[0].Value)
+		assert.Equal(t, []string{"gzip", "deflate"}, (*headers)[1].Value)
+	})
+
+	t.Run("Append common HTTP headers", func(t *testing.T) {
+		headers := &Headers{}
+		headers.Append(
+			Header{Key: "Content-Type", Value: []string{"application/json"}},
+			Header{Key: "Authorization", Value: []string{"Bearer eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9"}},
+			Header{Key: "User-Agent", Value: []string{"Go-http-client/1.1"}},
+			Header{Key: "Accept", Value: []string{"*/*"}},
+			Header{Key: "X-Requested-With", Value: []string{"XMLHttpRequest"}},
+		)
+
+		assert.Len(t, *headers, 5)
+		assert.True(t, headers.Has("Content-Type"))
+		assert.True(t, headers.Has("Authorization"))
+		assert.True(t, headers.Has("User-Agent"))
+		assert.True(t, headers.Has("Accept"))
+		assert.True(t, headers.Has("X-Requested-With"))
+	})
 }
 
 func TestHeaders_Parse(t *testing.T) {

pkg/types/param.go

@@ -15,11 +15,13 @@ func (params Params) GetValue(key string) *[]string {
 	return nil
 }
 
-func (params *Params) Append(param Param) {
+func (params *Params) Append(param ...Param) {
-	if item := params.GetValue(param.Key); item != nil {
+	for _, p := range param {
-		*item = append(*item, param.Value...)
+		if item := params.GetValue(p.Key); item != nil {
+			*item = append(*item, p.Value...)
 		} else {
-		*params = append(*params, param)
+			*params = append(*params, p)
+		}
 	}
 }
 

pkg/types/param_test.go

@@ -88,6 +88,39 @@ func TestParams_Append(t *testing.T) {
 		assert.Len(t, *params, 3)
 	})
 
+	t.Run("Append multiple parameters in single call", func(t *testing.T) {
+		params := &Params{}
+		params.Append(
+			Param{Key: "name", Value: []string{"john"}},
+			Param{Key: "age", Value: []string{"25"}},
+			Param{Key: "city", Value: []string{"NYC"}},
+		)
+
+		assert.Len(t, *params, 3)
+		assert.Equal(t, "name", (*params)[0].Key)
+		assert.Equal(t, []string{"john"}, (*params)[0].Value)
+		assert.Equal(t, "age", (*params)[1].Key)
+		assert.Equal(t, []string{"25"}, (*params)[1].Value)
+		assert.Equal(t, "city", (*params)[2].Key)
+		assert.Equal(t, []string{"NYC"}, (*params)[2].Value)
+	})
+
+	t.Run("Append multiple with existing keys", func(t *testing.T) {
+		params := &Params{
+			{Key: "tags", Value: []string{"go"}},
+		}
+		params.Append(
+			Param{Key: "tags", Value: []string{"test"}},
+			Param{Key: "tags", Value: []string{"api"}},
+			Param{Key: "version", Value: []string{"1.0"}},
+		)
+
+		assert.Len(t, *params, 2)
+		assert.Equal(t, []string{"go", "test", "api"}, (*params)[0].Value)
+		assert.Equal(t, "version", (*params)[1].Key)
+		assert.Equal(t, []string{"1.0"}, (*params)[1].Value)
+	})
+
 	t.Run("Append multiple values at once", func(t *testing.T) {
 		params := &Params{
 			{Key: "colors", Value: []string{"red"}},
@@ -105,6 +138,60 @@ func TestParams_Append(t *testing.T) {
 		assert.Len(t, *params, 1)
 		assert.Equal(t, []string{""}, (*params)[0].Value)
 	})
+
+	t.Run("Append no parameters", func(t *testing.T) {
+		params := &Params{
+			{Key: "existing", Value: []string{"value"}},
+		}
+		params.Append()
+
+		assert.Len(t, *params, 1)
+		assert.Equal(t, "existing", (*params)[0].Key)
+		assert.Equal(t, []string{"value"}, (*params)[0].Value)
+	})
+
+	t.Run("Append mixed new and existing keys", func(t *testing.T) {
+		params := &Params{
+			{Key: "filter", Value: []string{"active"}},
+			{Key: "sort", Value: []string{"name"}},
+		}
+		params.Append(
+			Param{Key: "filter", Value: []string{"verified"}},
+			Param{Key: "limit", Value: []string{"10"}},
+			Param{Key: "sort", Value: []string{"date"}},
+			Param{Key: "offset", Value: []string{"0"}},
+		)
+
+		assert.Len(t, *params, 4)
+
+		filterValue := params.GetValue("filter")
+		require.NotNil(t, filterValue)
+		assert.Equal(t, []string{"active", "verified"}, *filterValue)
+
+		sortValue := params.GetValue("sort")
+		require.NotNil(t, sortValue)
+		assert.Equal(t, []string{"name", "date"}, *sortValue)
+
+		limitValue := params.GetValue("limit")
+		require.NotNil(t, limitValue)
+		assert.Equal(t, []string{"10"}, *limitValue)
+
+		offsetValue := params.GetValue("offset")
+		require.NotNil(t, offsetValue)
+		assert.Equal(t, []string{"0"}, *offsetValue)
+	})
+
+	t.Run("Append parameters with multiple values", func(t *testing.T) {
+		params := &Params{}
+		params.Append(
+			Param{Key: "ids", Value: []string{"1", "2", "3"}},
+			Param{Key: "types", Value: []string{"A", "B"}},
+		)
+
+		assert.Len(t, *params, 2)
+		assert.Equal(t, []string{"1", "2", "3"}, (*params)[0].Value)
+		assert.Equal(t, []string{"A", "B"}, (*params)[1].Value)
+	})
 }
 
 func TestParams_Parse(t *testing.T) {

pkg/types/proxy.go

@@ -13,8 +13,8 @@ func (proxy Proxy) String() string {
 
 type Proxies []Proxy
 
-func (proxies *Proxies) Append(proxy Proxy) {
+func (proxies *Proxies) Append(proxy ...Proxy) {
-	*proxies = append(*proxies, proxy)
+	*proxies = append(*proxies, proxy...)
 }
 
 func (proxies *Proxies) Parse(rawValue string) error {

pkg/types/proxy_test.go

@@ -63,7 +63,7 @@ func TestProxies_Append(t *testing.T) {
 		assert.Equal(t, "http://proxy1.example.com:8080", (*proxies)[0].String())
 	})
 
-	t.Run("Append multiple proxies", func(t *testing.T) {
+	t.Run("Append multiple proxies sequentially", func(t *testing.T) {
 		proxies := &Proxies{}
 
 		url1, err := url.Parse("http://proxy1.example.com:8080")
@@ -83,6 +83,24 @@ func TestProxies_Append(t *testing.T) {
 		assert.Equal(t, "https://proxy3.example.com:443", (*proxies)[2].String())
 	})
 
+	t.Run("Append multiple proxies in single call", func(t *testing.T) {
+		proxies := &Proxies{}
+
+		url1, err := url.Parse("http://proxy1.example.com:8080")
+		require.NoError(t, err)
+		url2, err := url.Parse("http://proxy2.example.com:8081")
+		require.NoError(t, err)
+		url3, err := url.Parse("https://proxy3.example.com:443")
+		require.NoError(t, err)
+
+		proxies.Append(Proxy(*url1), Proxy(*url2), Proxy(*url3))
+
+		assert.Len(t, *proxies, 3)
+		assert.Equal(t, "http://proxy1.example.com:8080", (*proxies)[0].String())
+		assert.Equal(t, "http://proxy2.example.com:8081", (*proxies)[1].String())
+		assert.Equal(t, "https://proxy3.example.com:443", (*proxies)[2].String())
+	})
+
 	t.Run("Append to existing proxies", func(t *testing.T) {
 		existingURL, err := url.Parse("http://existing.example.com:8080")
 		require.NoError(t, err)
@@ -98,6 +116,77 @@ func TestProxies_Append(t *testing.T) {
 		assert.Equal(t, "http://existing.example.com:8080", (*proxies)[0].String())
 		assert.Equal(t, "http://new.example.com:8081", (*proxies)[1].String())
 	})
+
+	t.Run("Append multiple to existing proxies", func(t *testing.T) {
+		existingURL, err := url.Parse("http://existing.example.com:8080")
+		require.NoError(t, err)
+
+		proxies := &Proxies{Proxy(*existingURL)}
+
+		url1, err := url.Parse("http://new1.example.com:8081")
+		require.NoError(t, err)
+		url2, err := url.Parse("http://new2.example.com:8082")
+		require.NoError(t, err)
+		url3, err := url.Parse("https://new3.example.com:443")
+		require.NoError(t, err)
+
+		proxies.Append(Proxy(*url1), Proxy(*url2), Proxy(*url3))
+
+		assert.Len(t, *proxies, 4)
+		assert.Equal(t, "http://existing.example.com:8080", (*proxies)[0].String())
+		assert.Equal(t, "http://new1.example.com:8081", (*proxies)[1].String())
+		assert.Equal(t, "http://new2.example.com:8082", (*proxies)[2].String())
+		assert.Equal(t, "https://new3.example.com:443", (*proxies)[3].String())
+	})
+
+	t.Run("Append no proxies", func(t *testing.T) {
+		existingURL, err := url.Parse("http://existing.example.com:8080")
+		require.NoError(t, err)
+
+		proxies := &Proxies{Proxy(*existingURL)}
+		proxies.Append()
+
+		assert.Len(t, *proxies, 1)
+		assert.Equal(t, "http://existing.example.com:8080", (*proxies)[0].String())
+	})
+
+	t.Run("Append mixed proxies", func(t *testing.T) {
+		proxies := &Proxies{}
+
+		url1, err := url.Parse("http://proxy1.example.com:8080")
+		require.NoError(t, err)
+		url2, err := url.Parse("socks5://proxy2.example.com:1080")
+		require.NoError(t, err)
+		url3, err := url.Parse("https://proxy3.example.com:443")
+		require.NoError(t, err)
+		url4, err := url.Parse("http://proxy4.example.com:3128")
+		require.NoError(t, err)
+
+		proxies.Append(Proxy(*url1), Proxy(*url2))
+		proxies.Append(Proxy(*url3))
+		proxies.Append(Proxy(*url4))
+
+		assert.Len(t, *proxies, 4)
+		assert.Equal(t, "http://proxy1.example.com:8080", (*proxies)[0].String())
+		assert.Equal(t, "socks5://proxy2.example.com:1080", (*proxies)[1].String())
+		assert.Equal(t, "https://proxy3.example.com:443", (*proxies)[2].String())
+		assert.Equal(t, "http://proxy4.example.com:3128", (*proxies)[3].String())
+	})
+
+	t.Run("Append proxies with authentication", func(t *testing.T) {
+		proxies := &Proxies{}
+
+		url1, err := url.Parse("http://user1:pass1@proxy1.example.com:8080")
+		require.NoError(t, err)
+		url2, err := url.Parse("https://user2:pass2@proxy2.example.com:443")
+		require.NoError(t, err)
+
+		proxies.Append(Proxy(*url1), Proxy(*url2))
+
+		assert.Len(t, *proxies, 2)
+		assert.Equal(t, "http://user1:pass1@proxy1.example.com:8080", (*proxies)[0].String())
+		assert.Equal(t, "https://user2:pass2@proxy2.example.com:443", (*proxies)[1].String())
+	})
 }
 
 func TestProxies_Parse(t *testing.T) {

pkg/utils/parse.go

@@ -0,0 +1,111 @@
+package utils
+
+import (
+	"fmt"
+	"net/url"
+	"strconv"
+	"time"
+)
+
+// ParseString attempts to parse the input string `s` into a value of the specified type T.
+// If parsing the string `s` fails for a supported type, it returns the zero value of T
+// and the parsing error.
+// /nolint:forcetypeassert,wrapcheck
+func ParseString[
+	T string | int | int8 | int16 | int32 | int64 | uint | uint8 | uint16 | uint32 | uint64 | float64 | bool | time.Duration | url.URL,
+](rawValue string) (T, error) {
+	var value T
+
+	switch any(value).(type) {
+	case int:
+		i, err := strconv.Atoi(rawValue)
+		if err != nil {
+			return value, err
+		}
+		value = any(i).(T)
+	case int8:
+		i, err := strconv.ParseInt(rawValue, 10, 8)
+		if err != nil {
+			return value, err
+		}
+		value = any(int8(i)).(T)
+	case int16:
+		i, err := strconv.ParseInt(rawValue, 10, 16)
+		if err != nil {
+			return value, err
+		}
+		value = any(int16(i)).(T)
+	case int32:
+		i, err := strconv.ParseInt(rawValue, 10, 32)
+		if err != nil {
+			return value, err
+		}
+		value = any(int32(i)).(T)
+	case int64:
+		i, err := strconv.ParseInt(rawValue, 10, 64)
+		if err != nil {
+			return value, err
+		}
+		value = any(i).(T)
+	case uint:
+		u, err := strconv.ParseUint(rawValue, 10, 0)
+		if err != nil {
+			return value, err
+		}
+		value = any(uint(u)).(T)
+	case uint8:
+		u, err := strconv.ParseUint(rawValue, 10, 8)
+		if err != nil {
+			return value, err
+		}
+		value = any(uint8(u)).(T)
+	case uint16:
+		u, err := strconv.ParseUint(rawValue, 10, 16)
+		if err != nil {
+			return value, err
+		}
+		value = any(uint16(u)).(T)
+	case uint32:
+		u, err := strconv.ParseUint(rawValue, 10, 32)
+		if err != nil {
+			return value, err
+		}
+		value = any(uint32(u)).(T)
+	case uint64:
+		u, err := strconv.ParseUint(rawValue, 10, 64)
+		if err != nil {
+			return value, err
+		}
+		value = any(u).(T)
+	case float64:
+		f, err := strconv.ParseFloat(rawValue, 64)
+		if err != nil {
+			return value, err
+		}
+		value = any(f).(T)
+	case bool:
+		b, err := strconv.ParseBool(rawValue)
+		if err != nil {
+			return value, err
+		}
+		value = any(b).(T)
+	case string:
+		value = any(rawValue).(T)
+	case time.Duration:
+		d, err := time.ParseDuration(rawValue)
+		if err != nil {
+			return value, err
+		}
+		value = any(d).(T)
+	case url.URL:
+		u, err := url.Parse(rawValue)
+		if err != nil {
+			return value, err
+		}
+		value = any(*u).(T)
+	default:
+		return value, fmt.Errorf("unsupported type: %T", value)
+	}
+
+	return value, nil
+}

pkg/utils/parse_test.go

@@ -0,0 +1,528 @@
+package utils
+
+import (
+	"net/url"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestParseString(t *testing.T) {
+	t.Run("ParseString to string", func(t *testing.T) {
+		tests := []struct {
+			name     string
+			input    string
+			expected string
+		}{
+			{"empty string", "", ""},
+			{"simple string", "hello", "hello"},
+			{"string with spaces", "hello world", "hello world"},
+			{"numeric string", "123", "123"},
+			{"special characters", "!@#$%^&*()", "!@#$%^&*()"},
+		}
+
+		for _, test := range tests {
+			t.Run(test.name, func(t *testing.T) {
+				result, err := ParseString[string](test.input)
+				require.NoError(t, err)
+				assert.Equal(t, test.expected, result)
+			})
+		}
+	})
+
+	t.Run("ParseString to int", func(t *testing.T) {
+		tests := []struct {
+			name        string
+			input       string
+			expected    int
+			expectError bool
+		}{
+			{"positive int", "42", 42, false},
+			{"negative int", "-42", -42, false},
+			{"zero", "0", 0, false},
+			{"invalid int", "abc", 0, true},
+			{"float string", "3.14", 0, true},
+			{"empty string", "", 0, true},
+			{"overflow string", "99999999999999999999", 0, true},
+		}
+
+		for _, test := range tests {
+			t.Run(test.name, func(t *testing.T) {
+				result, err := ParseString[int](test.input)
+				if test.expectError {
+					assert.Error(t, err)
+				} else {
+					require.NoError(t, err)
+					assert.Equal(t, test.expected, result)
+				}
+			})
+		}
+	})
+
+	t.Run("ParseString to int8", func(t *testing.T) {
+		tests := []struct {
+			name        string
+			input       string
+			expected    int8
+			expectError bool
+		}{
+			{"valid int8", "127", 127, false},
+			{"min int8", "-128", -128, false},
+			{"overflow int8", "128", 0, true},
+			{"underflow int8", "-129", 0, true},
+			{"invalid", "abc", 0, true},
+		}
+
+		for _, test := range tests {
+			t.Run(test.name, func(t *testing.T) {
+				result, err := ParseString[int8](test.input)
+				if test.expectError {
+					assert.Error(t, err)
+				} else {
+					require.NoError(t, err)
+					assert.Equal(t, test.expected, result)
+				}
+			})
+		}
+	})
+
+	t.Run("ParseString to int16", func(t *testing.T) {
+		tests := []struct {
+			name        string
+			input       string
+			expected    int16
+			expectError bool
+		}{
+			{"valid int16", "32767", 32767, false},
+			{"min int16", "-32768", -32768, false},
+			{"overflow int16", "32768", 0, true},
+			{"underflow int16", "-32769", 0, true},
+		}
+
+		for _, test := range tests {
+			t.Run(test.name, func(t *testing.T) {
+				result, err := ParseString[int16](test.input)
+				if test.expectError {
+					assert.Error(t, err)
+				} else {
+					require.NoError(t, err)
+					assert.Equal(t, test.expected, result)
+				}
+			})
+		}
+	})
+
+	t.Run("ParseString to int32", func(t *testing.T) {
+		tests := []struct {
+			name        string
+			input       string
+			expected    int32
+			expectError bool
+		}{
+			{"valid int32", "2147483647", 2147483647, false},
+			{"min int32", "-2147483648", -2147483648, false},
+			{"overflow int32", "2147483648", 0, true},
+			{"underflow int32", "-2147483649", 0, true},
+		}
+
+		for _, test := range tests {
+			t.Run(test.name, func(t *testing.T) {
+				result, err := ParseString[int32](test.input)
+				if test.expectError {
+					assert.Error(t, err)
+				} else {
+					require.NoError(t, err)
+					assert.Equal(t, test.expected, result)
+				}
+			})
+		}
+	})
+
+	t.Run("ParseString to int64", func(t *testing.T) {
+		tests := []struct {
+			name        string
+			input       string
+			expected    int64
+			expectError bool
+		}{
+			{"valid int64", "9223372036854775807", 9223372036854775807, false},
+			{"min int64", "-9223372036854775808", -9223372036854775808, false},
+			{"large number", "123456789012345", 123456789012345, false},
+			{"invalid", "not a number", 0, true},
+		}
+
+		for _, test := range tests {
+			t.Run(test.name, func(t *testing.T) {
+				result, err := ParseString[int64](test.input)
+				if test.expectError {
+					assert.Error(t, err)
+				} else {
+					require.NoError(t, err)
+					assert.Equal(t, test.expected, result)
+				}
+			})
+		}
+	})
+
+	t.Run("ParseString to uint", func(t *testing.T) {
+		tests := []struct {
+			name        string
+			input       string
+			expected    uint
+			expectError bool
+		}{
+			{"valid uint", "42", 42, false},
+			{"zero", "0", 0, false},
+			{"large uint", "4294967295", 4294967295, false},
+			{"negative", "-1", 0, true},
+			{"invalid", "abc", 0, true},
+		}
+
+		for _, test := range tests {
+			t.Run(test.name, func(t *testing.T) {
+				result, err := ParseString[uint](test.input)
+				if test.expectError {
+					assert.Error(t, err)
+				} else {
+					require.NoError(t, err)
+					assert.Equal(t, test.expected, result)
+				}
+			})
+		}
+	})
+
+	t.Run("ParseString to uint8", func(t *testing.T) {
+		tests := []struct {
+			name        string
+			input       string
+			expected    uint8
+			expectError bool
+		}{
+			{"valid uint8", "255", 255, false},
+			{"min uint8", "0", 0, false},
+			{"overflow uint8", "256", 0, true},
+			{"negative", "-1", 0, true},
+		}
+
+		for _, test := range tests {
+			t.Run(test.name, func(t *testing.T) {
+				result, err := ParseString[uint8](test.input)
+				if test.expectError {
+					assert.Error(t, err)
+				} else {
+					require.NoError(t, err)
+					assert.Equal(t, test.expected, result)
+				}
+			})
+		}
+	})
+
+	t.Run("ParseString to uint16", func(t *testing.T) {
+		tests := []struct {
+			name        string
+			input       string
+			expected    uint16
+			expectError bool
+		}{
+			{"valid uint16", "65535", 65535, false},
+			{"min uint16", "0", 0, false},
+			{"overflow uint16", "65536", 0, true},
+			{"negative", "-1", 0, true},
+		}
+
+		for _, test := range tests {
+			t.Run(test.name, func(t *testing.T) {
+				result, err := ParseString[uint16](test.input)
+				if test.expectError {
+					assert.Error(t, err)
+				} else {
+					require.NoError(t, err)
+					assert.Equal(t, test.expected, result)
+				}
+			})
+		}
+	})
+
+	t.Run("ParseString to uint32", func(t *testing.T) {
+		tests := []struct {
+			name        string
+			input       string
+			expected    uint32
+			expectError bool
+		}{
+			{"valid uint32", "4294967295", 4294967295, false},
+			{"min uint32", "0", 0, false},
+			{"overflow uint32", "4294967296", 0, true},
+			{"negative", "-1", 0, true},
+		}
+
+		for _, test := range tests {
+			t.Run(test.name, func(t *testing.T) {
+				result, err := ParseString[uint32](test.input)
+				if test.expectError {
+					assert.Error(t, err)
+				} else {
+					require.NoError(t, err)
+					assert.Equal(t, test.expected, result)
+				}
+			})
+		}
+	})
+
+	t.Run("ParseString to uint64", func(t *testing.T) {
+		tests := []struct {
+			name        string
+			input       string
+			expected    uint64
+			expectError bool
+		}{
+			{"valid uint64", "18446744073709551615", 18446744073709551615, false},
+			{"min uint64", "0", 0, false},
+			{"large number", "123456789012345", 123456789012345, false},
+			{"negative", "-1", 0, true},
+			{"invalid", "not a number", 0, true},
+		}
+
+		for _, test := range tests {
+			t.Run(test.name, func(t *testing.T) {
+				result, err := ParseString[uint64](test.input)
+				if test.expectError {
+					assert.Error(t, err)
+				} else {
+					require.NoError(t, err)
+					assert.Equal(t, test.expected, result)
+				}
+			})
+		}
+	})
+
+	t.Run("ParseString to float64", func(t *testing.T) {
+		tests := []struct {
+			name        string
+			input       string
+			expected    float64
+			expectError bool
+		}{
+			{"integer", "42", 42.0, false},
+			{"decimal", "3.14159", 3.14159, false},
+			{"negative", "-2.5", -2.5, false},
+			{"scientific notation", "1.23e10", 1.23e10, false},
+			{"zero", "0", 0.0, false},
+			{"invalid", "not a number", 0, true},
+			{"empty", "", 0, true},
+		}
+
+		for _, test := range tests {
+			t.Run(test.name, func(t *testing.T) {
+				result, err := ParseString[float64](test.input)
+				if test.expectError {
+					assert.Error(t, err)
+				} else {
+					require.NoError(t, err)
+					assert.InDelta(t, test.expected, result, 0.0001)
+				}
+			})
+		}
+	})
+
+	t.Run("ParseString to bool", func(t *testing.T) {
+		tests := []struct {
+			name        string
+			input       string
+			expected    bool
+			expectError bool
+		}{
+			{"true lowercase", "true", true, false},
+			{"True mixed case", "True", true, false},
+			{"TRUE uppercase", "TRUE", true, false},
+			{"1 as true", "1", true, false},
+			{"false lowercase", "false", false, false},
+			{"False mixed case", "False", false, false},
+			{"FALSE uppercase", "FALSE", false, false},
+			{"0 as false", "0", false, false},
+			{"invalid", "yes", false, true},
+			{"empty", "", false, true},
+			{"numeric non-binary", "2", false, true},
+		}
+
+		for _, test := range tests {
+			t.Run(test.name, func(t *testing.T) {
+				result, err := ParseString[bool](test.input)
+				if test.expectError {
+					assert.Error(t, err)
+				} else {
+					require.NoError(t, err)
+					assert.Equal(t, test.expected, result)
+				}
+			})
+		}
+	})
+
+	t.Run("ParseString to time.Duration", func(t *testing.T) {
+		tests := []struct {
+			name        string
+			input       string
+			expected    time.Duration
+			expectError bool
+		}{
+			{"seconds", "10s", 10 * time.Second, false},
+			{"minutes", "5m", 5 * time.Minute, false},
+			{"hours", "2h", 2 * time.Hour, false},
+			{"combined", "1h30m45s", time.Hour + 30*time.Minute + 45*time.Second, false},
+			{"milliseconds", "500ms", 500 * time.Millisecond, false},
+			{"microseconds", "100us", 100 * time.Microsecond, false},
+			{"nanoseconds", "50ns", 50 * time.Nanosecond, false},
+			{"negative", "-5s", -5 * time.Second, false},
+			{"invalid", "5x", 0, true},
+			{"empty", "", 0, true},
+			{"no unit", "100", 0, true},
+		}
+
+		for _, test := range tests {
+			t.Run(test.name, func(t *testing.T) {
+				result, err := ParseString[time.Duration](test.input)
+				if test.expectError {
+					assert.Error(t, err)
+				} else {
+					require.NoError(t, err)
+					assert.Equal(t, test.expected, result)
+				}
+			})
+		}
+	})
+
+	t.Run("ParseString to url.URL", func(t *testing.T) {
+		tests := []struct {
+			name        string
+			input       string
+			checkFunc   func(t *testing.T, u url.URL)
+			expectError bool
+		}{
+			{
+				name:  "http URL",
+				input: "http://example.com",
+				checkFunc: func(t *testing.T, u url.URL) {
+					t.Helper()
+					assert.Equal(t, "http", u.Scheme)
+					assert.Equal(t, "example.com", u.Host)
+				},
+				expectError: false,
+			},
+			{
+				name:  "https URL with path",
+				input: "https://example.com/path/to/resource",
+				checkFunc: func(t *testing.T, u url.URL) {
+					t.Helper()
+					assert.Equal(t, "https", u.Scheme)
+					assert.Equal(t, "example.com", u.Host)
+					assert.Equal(t, "/path/to/resource", u.Path)
+				},
+				expectError: false,
+			},
+			{
+				name:  "URL with query parameters",
+				input: "https://example.com/search?q=test&page=1",
+				checkFunc: func(t *testing.T, u url.URL) {
+					t.Helper()
+					assert.Equal(t, "https", u.Scheme)
+					assert.Equal(t, "example.com", u.Host)
+					assert.Equal(t, "/search", u.Path)
+					assert.Equal(t, "q=test&page=1", u.RawQuery)
+				},
+				expectError: false,
+			},
+			{
+				name:  "URL with port",
+				input: "http://localhost:8080/api",
+				checkFunc: func(t *testing.T, u url.URL) {
+					t.Helper()
+					assert.Equal(t, "http", u.Scheme)
+					assert.Equal(t, "localhost:8080", u.Host)
+					assert.Equal(t, "/api", u.Path)
+				},
+				expectError: false,
+			},
+			{
+				name:  "URL with fragment",
+				input: "https://example.com/page#section",
+				checkFunc: func(t *testing.T, u url.URL) {
+					t.Helper()
+					assert.Equal(t, "https", u.Scheme)
+					assert.Equal(t, "example.com", u.Host)
+					assert.Equal(t, "/page", u.Path)
+					assert.Equal(t, "section", u.Fragment)
+				},
+				expectError: false,
+			},
+			{
+				name:  "relative path",
+				input: "/path/to/resource",
+				checkFunc: func(t *testing.T, u url.URL) {
+					t.Helper()
+					assert.Empty(t, u.Scheme)
+					assert.Empty(t, u.Host)
+					assert.Equal(t, "/path/to/resource", u.Path)
+				},
+				expectError: false,
+			},
+			{
+				name:  "empty string",
+				input: "",
+				checkFunc: func(t *testing.T, u url.URL) {
+					t.Helper()
+					assert.Empty(t, u.String())
+				},
+				expectError: false,
+			},
+		}
+
+		for _, test := range tests {
+			t.Run(test.name, func(t *testing.T) {
+				result, err := ParseString[url.URL](test.input)
+				if test.expectError {
+					assert.Error(t, err)
+				} else {
+					require.NoError(t, err)
+					if test.checkFunc != nil {
+						test.checkFunc(t, result)
+					}
+				}
+			})
+		}
+	})
+
+	t.Run("Edge cases", func(t *testing.T) {
+		t.Run("whitespace handling for numeric types", func(t *testing.T) {
+			result, err := ParseString[int]("  42  ")
+			require.Error(t, err)
+			assert.Equal(t, 0, result)
+		})
+
+		t.Run("leading zeros for int", func(t *testing.T) {
+			result, err := ParseString[int]("007")
+			require.NoError(t, err)
+			assert.Equal(t, 7, result)
+		})
+
+		t.Run("plus sign for positive numbers", func(t *testing.T) {
+			result, err := ParseString[int]("+42")
+			require.NoError(t, err)
+			assert.Equal(t, 42, result)
+		})
+
+		t.Run("case sensitivity for bool", func(t *testing.T) {
+			testCases := []string{"t", "T", "f", "F"}
+			for _, tc := range testCases {
+				result, err := ParseString[bool](tc)
+				require.NoError(t, err)
+				if tc == "t" || tc == "T" {
+					assert.True(t, result)
+				} else {
+					assert.False(t, result)
+				}
+			}
+		})
+	})
+}