Implement a test for InternalErrorWith on go 1.13

errors_1_13_test.go

@@ -0,0 +1,48 @@
+// Copyright 2018 Twitch Interactive, Inc.  All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License"). You may not
+// use this file except in compliance with the License. A copy of the License is
+// located at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// or in the "license" file accompanying this file. This file is distributed on
+// an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+// express or implied. See the License for the specific language governing
+// permissions and limitations under the License.
+
+// +build go1.13
+
+package twirp_test
+
+import (
+	"errors"
+	"fmt"
+	"testing"
+
+	"github.com/twitchtv/twirp"
+)
+
+type myError string
+
+func (e myError) Error() string {
+	return string(e)
+}
+
+func TestInternalErrorWith_Unwrap(t *testing.T) {
+	myErr := myError("myError")
+	wrErr := fmt.Errorf("wrapped: %w", myErr) // double wrap
+	twerr := twirp.InternalErrorWith(wrErr)
+
+	if !errors.Is(twerr, myErr) {
+		t.Errorf("expected errors.Is to match the error wrapped by twirp.InternalErrorWith")
+	}
+
+	var errTarget myError
+	if !errors.As(twerr, &errTarget) {
+		t.Errorf("expected errors.As to match the error wrapped by twirp.InternalErrorWith")
+	}
+	if errTarget.Error() != myErr.Error() {
+		t.Errorf("invalid value for errTarget.Error(). have=%q, want=%q", errTarget.Error(), myErr.Error())
+	}
+}