feat(error): support go 1.13 errors.Unwrap method

.gitignore

@@ -0,0 +1,2 @@
+/.idea
+.DS_Store

error.go

@@ -0,0 +1,49 @@
+// Copyright 2020 PingCAP, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package fn
+
+type statusCodeError struct {
+	err        error
+	statusCode int
+}
+
+type StatusCodeError interface {
+	StatusCode() int
+}
+
+func (s *statusCodeError) StatusCode() int {
+	return s.statusCode
+}
+
+func (s *statusCodeError) Unwrap() error {
+	return s.err
+}
+
+func (s *statusCodeError) Error() string {
+	return s.err.Error()
+}
+
+func UnwrapErrorStatusCode(err error) (int, bool) {
+	for err != nil {
+		if v, ok := err.(StatusCodeError); ok {
+			return v.StatusCode(), true
+		}
+		err = Unwrap(err)
+	}
+	return 0, false
+}
+
+func ErrorWithStatusCode(err error, statusCode int) error {
+	return &statusCodeError{err, statusCode}
+}

error_test.go

@@ -0,0 +1,63 @@
+// Copyright 2020 PingCAP, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package fn
+
+import (
+	"errors"
+	"net/http"
+	"testing"
+
+	. "github.com/pingcap/check"
+)
+
+var (
+	errTest = errors.New("test")
+)
+
+type withError struct {
+	err error
+}
+
+func (w *withError) Error() string {
+	return w.err.Error()
+}
+
+func (w *withError) Unwrap() error {
+	return w.err
+}
+
+type errSuite struct{}
+
+func TestError(t *testing.T) {
+	TestingT(t)
+}
+
+var _ = Suite(&errSuite{})
+
+// TestWithError test UnwrapErrorStatusCode method
+func (e *errSuite) TestWithError(c *C) {
+	var err error = &withError{
+		err: ErrorWithStatusCode(errTest, http.StatusInternalServerError),
+	}
+	code, ok := UnwrapErrorStatusCode(err)
+	c.Assert(ok, IsTrue)
+	c.Assert(code == http.StatusInternalServerError, IsTrue)
+}
+
+// TestOriginError ErrorWithStatusCode Unwrap
+func (e *errSuite) TestOriginError(c *C) {
+	err := ErrorWithStatusCode(errTest, http.StatusInternalServerError)
+	err = Unwrap(err)
+	c.Assert(err == errTest, IsTrue)
+}

go113.go

@@ -0,0 +1,22 @@
+//+build go1.13
+
+// Copyright 2020 PingCAP, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package fn
+
+import "errors"
+
+func Unwrap(err error) error {
+	return errors.Unwrap(err)
+}

interface.go

@@ -109,7 +109,3 @@ func SetResponseEncoder(c ResponseEncoder) {
 func SetMultipartFormMaxMemory(m int64) {
 	maxMemory = m
 }
-
-func ErrorWithStatusCode(err error, statusCode int) error {
-	return &statusCodeError{err, statusCode}
-}

pre_go113.go

@@ -0,0 +1,28 @@
+//+build !go1.13
+
+// Copyright 2020 PingCAP, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package fn
+
+type wrapError interface {
+	Unwrap() error
+}
+
+func Unwrap(err error) error {
+	u, ok := err.(wrapError)
+	if !ok {
+		return nil
+	}
+	return u.Unwrap()
+}

wrapper.go

@@ -15,9 +15,9 @@ package fn
 
 import (
 	"context"
-	"reflect"
 	"encoding/json"
 	"net/http"
+	"reflect"
 )
 
 type (
@@ -32,40 +32,27 @@ type (
 		plugins []PluginFunc
 		adapter adapter
 	}
-
-	statusCodeError struct {
-		error
-		statusCode int
-	}
-
-	StatusCodeError interface {
-		StatusCode() int
-	}
 )
 
 var (
 	errorEncoder    ErrorEncoder
 	responseEncoder ResponseEncoder
 )
 
-func (s *statusCodeError) StatusCode() int {
-	return s.statusCode
-}
-
 func failure(ctx context.Context, w http.ResponseWriter, err error) {
 	statusCode := http.StatusBadRequest
-	if v, ok := err.(StatusCodeError); ok {
-		statusCode = v.StatusCode()
+	if v, ok := UnwrapErrorStatusCode(err); ok {
+		statusCode = v
 	}
 	w.WriteHeader(statusCode)
-	json.NewEncoder(w).Encode(errorEncoder(ctx, err))
+	_ = json.NewEncoder(w).Encode(errorEncoder(ctx, err))
 }
 
 func success(ctx context.Context, w http.ResponseWriter, data interface{}) {
 	if data == nil || (reflect.ValueOf(data).Kind() == reflect.Ptr && reflect.ValueOf(data).IsNil()) {
 		w.WriteHeader(http.StatusNoContent)
 	} else {
-		json.NewEncoder(w).Encode(responseEncoder(ctx, data))
+		_ = json.NewEncoder(w).Encode(responseEncoder(ctx, data))
 	}
 }
 

wrapper_test.go

@@ -172,7 +172,7 @@ func (s *fnSuite) TestSetResponseEncoder(c *C) {
 	c.Assert(err, IsNil)
 	handler.ServeHTTP(recorder, request)
 	respMsg := &testResponse{}
-	json.Unmarshal(recorder.Body.Bytes(), &respMsg)
+	_ = json.Unmarshal(recorder.Body.Bytes(), &respMsg)
 	c.Assert(reflect.DeepEqual(respMsg, testResp), IsTrue)
 }
 
@@ -195,7 +195,7 @@ func (s *fnSuite) TestSetErrorEncoder(c *C) {
 	handler.ServeHTTP(recorder, request)
 
 	respMsg := &testErrorResponse{}
-	json.Unmarshal(recorder.Body.Bytes(), &respMsg)
+	_ = json.Unmarshal(recorder.Body.Bytes(), &respMsg)
 	c.Assert(reflect.DeepEqual(respMsg, testErrorResp), IsTrue)
 }
 
@@ -207,6 +207,7 @@ func (s *fnSuite) TestGenericAdapter_Invoke(c *C) {
 
 	recorder := httptest.NewRecorder()
 	request, err := http.NewRequest(http.MethodGet, "", nil)
+	c.Assert(err == nil, IsTrue)
 	payload := []byte(`{"for":"hello", "bar":10000}`)
 	request.Body = ioutil.NopCloser(bytes.NewBuffer(payload))
 	c.Assert(err, IsNil)