Improve error message

internal/mongo/errors.go

@@ -1,20 +1,31 @@
 package mongo
 
-// GenerationError is an error from generating MongoDB repository
-type GenerationError string
+import (
+	"fmt"
+)
 
-func (err GenerationError) Error() string {
-	switch err {
-	case OperationNotSupportedError:
-		return "operation not supported"
-	case BsonTagNotFoundError:
-		return "bson tag not found"
-	}
-	return string(err)
+// NewOperationNotSupportedError creates operationNotSupportedError
+func NewOperationNotSupportedError(operationName string) error {
+	return operationNotSupportedError{OperationName: operationName}
 }
 
-// generation error constants
-const (
-	OperationNotSupportedError GenerationError = "ERROR_OPERATION_NOT_SUPPORTED"
-	BsonTagNotFoundError       GenerationError = "ERROR_BSON_TAG_NOT_FOUND"
-)
+type operationNotSupportedError struct {
+	OperationName string
+}
+
+func (err operationNotSupportedError) Error() string {
+	return fmt.Sprintf("operation '%s' not supported", err.OperationName)
+}
+
+// NewBsonTagNotFoundError creates bsonTagNotFoundError
+func NewBsonTagNotFoundError(fieldName string) error {
+	return bsonTagNotFoundError{FieldName: fieldName}
+}
+
+type bsonTagNotFoundError struct {
+	FieldName string
+}
+
+func (err bsonTagNotFoundError) Error() string {
+	return fmt.Sprintf("bson tag of field '%s' not found", err.FieldName)
+}

internal/mongo/errors_test.go

@@ -0,0 +1,36 @@
+package mongo_test
+
+import (
+	"testing"
+
+	"github.com/sunboyy/repogen/internal/mongo"
+)
+
+type ErrorTestCase struct {
+	Name           string
+	Error          error
+	ExpectedString string
+}
+
+func TestError(t *testing.T) {
+	testTable := []ErrorTestCase{
+		{
+			Name:           "OperationNotSupportedError",
+			Error:          mongo.NewOperationNotSupportedError("Stub"),
+			ExpectedString: "operation 'Stub' not supported",
+		},
+		{
+			Name:           "BsonTagNotFoundError",
+			Error:          mongo.NewBsonTagNotFoundError("AccessToken"),
+			ExpectedString: "bson tag of field 'AccessToken' not found",
+		},
+	}
+
+	for _, testCase := range testTable {
+		t.Run(testCase.Name, func(t *testing.T) {
+			if testCase.Error.Error() != testCase.ExpectedString {
+				t.Errorf("Expected = %v\nReceived = %v", testCase.ExpectedString, testCase.Error.Error())
+			}
+		})
+	}
+}

internal/mongo/generator.go

@@ -87,9 +87,9 @@ func (g RepositoryGenerator) generateMethodImplementation(methodSpec spec.Method
 		return g.generateDeleteImplementation(operation)
 	case spec.CountOperation:
 		return g.generateCountImplementation(operation)
+	default:
+		return "", NewOperationNotSupportedError(operation.Name())
 	}
-
-	return "", OperationNotSupportedError
 }
 
 func (g RepositoryGenerator) generateInsertImplementation(operation spec.InsertOperation) (string, error) {
@@ -201,7 +201,7 @@ func (g RepositoryGenerator) bsonTagFromFieldName(fieldName string) (string, err
 
 	bsonTag, ok := structField.Tags["bson"]
 	if !ok {
-		return "", BsonTagNotFoundError
+		return "", NewBsonTagNotFoundError(fieldName)
 	}
 
 	return bsonTag[0], nil

internal/mongo/generator_test.go

@@ -1453,6 +1453,13 @@ type GenerateMethodInvalidTestCase struct {
 	ExpectedError error
 }
 
+type StubOperation struct {
+}
+
+func (o StubOperation) Name() string {
+	return "Stub"
+}
+
 func TestGenerateMethod_Invalid(t *testing.T) {
 	testTable := []GenerateMethodInvalidTestCase{
 		{
@@ -1467,9 +1474,9 @@ func TestGenerateMethod_Invalid(t *testing.T) {
 					code.ArrayType{ContainedType: code.PointerType{ContainedType: code.SimpleType("UserModel")}},
 					code.SimpleType("error"),
 				},
-				Operation: "search",
+				Operation: StubOperation{},
 			},
-			ExpectedError: mongo.OperationNotSupportedError,
+			ExpectedError: mongo.NewOperationNotSupportedError("Stub"),
 		},
 		{
 			Name: "bson tag not found in query",
@@ -1492,7 +1499,7 @@ func TestGenerateMethod_Invalid(t *testing.T) {
 					},
 				},
 			},
-			ExpectedError: mongo.BsonTagNotFoundError,
+			ExpectedError: mongo.NewBsonTagNotFoundError("AccessToken"),
 		},
 		{
 			Name: "bson tag not found in update field",
@@ -1519,7 +1526,7 @@ func TestGenerateMethod_Invalid(t *testing.T) {
 					},
 				},
 			},
-			ExpectedError: mongo.BsonTagNotFoundError,
+			ExpectedError: mongo.NewBsonTagNotFoundError("AccessToken"),
 		},
 	}