feat(googleapi): inject gax apierror.APIError into googleapi.Error

refs: googleapis/gax-go#238

googleapi/googleapi.go

@@ -79,6 +79,8 @@ type Error struct {
 	Header http.Header
 
 	Errors []ErrorItem
+	// Err is a wrapped apierror.APIError, typically derived from this Error.
+	Err error
 }
 
 // ErrorItem is a detailed error code & message from the Google API frontend.
@@ -122,6 +124,10 @@ func (e *Error) Error() string {
 	return buf.String()
 }
 
+func (e *Error) Unwrap() error {
+	return e.Err
+}
+
 type errorReply struct {
 	Error *Error `json:"error"`
 }

internal/gensupport/error.go

@@ -0,0 +1,22 @@
+// Copyright 2020 Google LLC. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package gensupport
+
+import (
+	"github.com/googleapis/gax-go/v2/apierror"
+	"google.golang.org/api/googleapi"
+)
+
+// WrapError creates an apierror.APIError from err (one that
+// does not wrap err), wraps it in err, and returns err. If
+// err is not a googleapi.Error (or a gRPC Status), it returns
+// err without modification.
+func WrapError(err *googleapi.Error) *googleapi.Error {
+	// TODO: Update this call to apierror.FromWrappingError once it is available.
+	if apiError, ok := apierror.FromError(err); ok {
+		err.Err = apiError
+	}
+	return err
+}

internal/gensupport/error_test.go

@@ -0,0 +1,48 @@
+// Copyright 2019 Google LLC.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package gensupport
+
+import (
+	"errors"
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+	"github.com/googleapis/gax-go/v2/apierror"
+	"google.golang.org/api/googleapi"
+	"google.golang.org/genproto/googleapis/rpc/errdetails"
+	"google.golang.org/protobuf/proto"
+)
+
+func TestWrapError(t *testing.T) {
+	// The error format v2 for Google JSON REST APIs, per https://cloud.google.com/apis/design/errors#http_mapping.
+	jsonErrStr := "{\"error\":{\"details\":[{\"@type\":\"type.googleapis.com/google.rpc.ErrorInfo\", \"reason\":\"just because\", \"domain\":\"tests\"}]}}"
+	hae := &googleapi.Error{
+		Body: jsonErrStr,
+	}
+	hae = WrapError(hae)
+
+	var aerr *apierror.APIError
+	if ok := errors.As(hae, &aerr); !ok {
+		t.Errorf("got false, want true")
+	}
+
+	httpErrInfo := &errdetails.ErrorInfo{Reason: "just because", Domain: "tests"}
+	details := apierror.ErrDetails{ErrorInfo: httpErrInfo}
+	if diff := cmp.Diff(aerr.Details(), details, cmp.Comparer(proto.Equal)); diff != "" {
+		t.Errorf("got(-), want(+),: \n%s", diff)
+	}
+	if s := aerr.Reason(); s != "just because" {
+		t.Errorf("Reason() got %s, want 'just because'", s)
+	}
+	if s := aerr.Domain(); s != "tests" {
+		t.Errorf("Domain() got %s, want nil", s)
+	}
+	if err := aerr.Unwrap(); err != nil {
+		t.Errorf("Unwrap() got %T, want nil", err)
+	}
+	if m := aerr.Metadata(); m != nil {
+		t.Errorf("Metadata() got %v, want nil", m)
+	}
+}