add config file parser

pkg/types/errors.go

@@ -63,6 +63,25 @@ func (e FieldParseErrors) Error() string {
 	return errorString
 }
 
+type UnmarshalError struct {
+	error error
+}
+
+func NewUnmarshalError(err error) UnmarshalError {
+	if err == nil {
+		err = ErrNoError
+	}
+	return UnmarshalError{err}
+}
+
+func (e UnmarshalError) Error() string {
+	return "Unmarshal error: " + e.error.Error()
+}
+
+func (e UnmarshalError) Unwrap() error {
+	return e.error
+}
+
 // ======================================== CLI ========================================
 
 type CLIUnexpectedArgsError struct {

pkg/types/errors_test.go

@@ -205,20 +205,50 @@ func TestNewRemoteConfigFileParseError(t *testing.T) {
 	})
 }
 
-func TestErrorConstants(t *testing.T) {
-	t.Run("ErrNoError has correct message", func(t *testing.T) {
-		expected := "no error (internal)"
-		assert.Equal(t, expected, ErrNoError.Error())
+func TestUnmarshalError_Error(t *testing.T) {
+	t.Run("Error returns formatted message", func(t *testing.T) {
+		originalErr := errors.New("yaml parsing failed")
+		err := NewUnmarshalError(originalErr)
+
+		expected := "Unmarshal error: yaml parsing failed"
+		assert.Equal(t, expected, err.Error())
 	})
 
-	t.Run("ErrCLINoArgs has correct message", func(t *testing.T) {
-		expected := "CLI expects arguments but received none"
-		assert.Equal(t, expected, ErrCLINoArgs.Error())
+	t.Run("Error with nil underlying error", func(t *testing.T) {
+		err := NewUnmarshalError(nil)
+
+		expected := "Unmarshal error: no error (internal)"
+		assert.Equal(t, expected, err.Error())
+	})
+}
+
+func TestUnmarshalError_Unwrap(t *testing.T) {
+	t.Run("Unwrap returns original error", func(t *testing.T) {
+		originalErr := errors.New("original error")
+		err := NewUnmarshalError(originalErr)
+
+		assert.Equal(t, originalErr, err.Unwrap())
 	})
 
-	t.Run("ErrCLIUnexpectedArgs has correct message", func(t *testing.T) {
-		expected := "CLI received unexpected arguments"
-		assert.Equal(t, expected, ErrCLIUnexpectedArgs.Error())
+	t.Run("Unwrap with nil error", func(t *testing.T) {
+		err := NewUnmarshalError(nil)
+
+		assert.Equal(t, ErrNoError, err.Unwrap())
+	})
+}
+
+func TestNewUnmarshalError(t *testing.T) {
+	t.Run("Creates UnmarshalError with correct values", func(t *testing.T) {
+		originalErr := errors.New("test error")
+		err := NewUnmarshalError(originalErr)
+
+		assert.Equal(t, originalErr, err.error)
+	})
+
+	t.Run("Creates UnmarshalError with ErrNoError when nil passed", func(t *testing.T) {
+		err := NewUnmarshalError(nil)
+
+		assert.Equal(t, ErrNoError, err.error)
 	})
 }
 
@@ -242,4 +272,9 @@ func TestErrorImplementsErrorInterface(t *testing.T) {
 		var err error = NewRemoteConfigFileParseError(errors.New("test"))
 		assert.Error(t, err)
 	})
+
+	t.Run("UnmarshalError implements error interface", func(t *testing.T) {
+		var err error = NewUnmarshalError(errors.New("test"))
+		assert.Error(t, err)
+	})
 }