Add unit tests for field validation

template_validator.go

@@ -21,7 +21,7 @@ type ValidationError struct {
 }
 
 func (e *ValidationError) Error() string {
-	return fmt.Sprintf("template '%s' validation error: %s - %v", e.TemplateName, e.FieldPath, e.Err)
+	return fmt.Sprintf("template '%s' validation error: '%s' - '%s'", e.TemplateName, e.FieldPath, e.Err)
 }
 
 // validateTemplateFields analyzes template content and validates

template_validator_test.go

@@ -0,0 +1,104 @@
+package templator
+
+import (
+	"errors"
+	"reflect"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestValidator_Error(t *testing.T) {
+	t.Parallel()
+
+	validatorError := ValidationError{
+		TemplateName: "dummy-template-name",
+		FieldPath:    "dummy-file-path",
+		Err:          errors.New("dummy-error"),
+	}
+
+	got := validatorError.Error()
+
+	assert.Equal(t, "template 'dummy-template-name' validation error: 'dummy-file-path' - 'dummy-error'", got)
+}
+
+func TestUniqueFields(t *testing.T) {
+	t.Parallel()
+
+	testCases := []struct {
+		name        string
+		givenFields []string
+		expect      []string
+	}{
+		{
+			name:        "unique fields",
+			givenFields: []string{"foo", "bar"},
+			expect:      []string{"foo", "bar"},
+		},
+		{
+			name:        "duplicated fields",
+			givenFields: []string{"foo", "bar", "foo"},
+			expect:      []string{"foo", "bar"},
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			got := uniqueFields(tc.givenFields)
+
+			assert.ElementsMatch(t, tc.expect, got)
+		})
+	}
+}
+
+func Test_validateField(t *testing.T) {
+	t.Parallel()
+
+	type testStruct struct {
+		testField string
+	}
+
+	testCases := []struct {
+		name      string
+		typ       reflect.Type
+		fieldPath string
+		wantErr   bool
+	}{
+		{
+			name:      "nil type",
+			typ:       nil,
+			fieldPath: "testField",
+			wantErr:   true,
+		},
+		{
+			name:      "non-struct type",
+			typ:       reflect.TypeOf(""),
+			fieldPath: "testField",
+			wantErr:   true,
+		},
+		{
+			name:      "field is a struct",
+			typ:       reflect.TypeOf(testStruct{}),
+			fieldPath: "testField",
+			wantErr:   false,
+		},
+		{
+			name:      "field is a pointer",
+			typ:       reflect.TypeOf(&testStruct{}),
+			fieldPath: "testField",
+			wantErr:   false,
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			err := validateField(tc.typ, tc.fieldPath)
+
+			if tc.wantErr {
+				assert.Error(t, err)
+			} else {
+				assert.NoError(t, err)
+			}
+		})
+	}
+}