convert panic when it is not error (#2486)

common/log/panic.go

@@ -33,17 +33,15 @@ import (
 	"go.temporal.io/server/common/log/tag"
 )
 
-var errDefaultPanic = fmt.Errorf("panic object is not error")
-
 // CapturePanic is used to capture panic, it will log the panic and also return the error through pointer.
 // If the panic value is not error then a default error is returned
 // We have to use pointer is because in golang: "recover return nil if was not called directly by a deferred function."
 // And we have to set the returned error otherwise our handler will return nil as error which is incorrect
 func CapturePanic(logger Logger, retError *error) {
-	if errPanic := recover(); errPanic != nil {
-		err, ok := errPanic.(error)
+	if panicObj := recover(); panicObj != nil {
+		err, ok := panicObj.(error)
 		if !ok {
-			err = errDefaultPanic
+			err = fmt.Errorf("panic: %v", panicObj)
 		}
 
 		st := string(debug.Stack())

common/log/panic_test.go

@@ -0,0 +1,53 @@
+// The MIT License
+//
+// Copyright (c) 2020 Temporal Technologies Inc.  All rights reserved.
+//
+// Copyright (c) 2020 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package log
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestCapturePanic(t *testing.T) {
+	fooErr := testCapture("foo")
+	assert.Error(t, fooErr)
+	assert.Equal(t, "panic: foo", fooErr.Error())
+
+	barErr := testCapture(fmt.Errorf("error: %v", "bar"))
+	assert.Error(t, barErr)
+	assert.Equal(t, "error: bar", barErr.Error())
+}
+
+func testCapture(panicObj interface{}) (retErr error) {
+	defer CapturePanic(NewNoopLogger(), &retErr)
+
+	testPanic(panicObj)
+	return nil
+}
+
+func testPanic(panicObj interface{}) {
+	panic(panicObj)
+}