correctly propagate the hystrix error (#165)

* correctly propagate the hystrix error

* fix

* add timeout error unit tests

* remove errors.Is(), not supported by go1.12

* fix data race

interceptors/interceptors_test.go

@@ -4,11 +4,13 @@ import (
 	"context"
 	"strings"
 	"testing"
+	"time"
 
 	"google.golang.org/grpc/status"
 
 	"google.golang.org/grpc/codes"
 
+	"github.com/afex/hystrix-go/hystrix"
 	"github.com/carousell/Orion/utils/errors"
 	"google.golang.org/grpc"
 )
@@ -33,6 +35,28 @@ func TestHystrixClientInterceptorPanicRecovery(t *testing.T) {
 	}
 }
 
+func TestHystrixClientInterceptorTimeoutError(t *testing.T) {
+
+	// default hystrix timeout is 1000 ms
+	invoker := func(ctx context.Context, method string, req, reply interface{}, cc *grpc.ClientConn, opts ...grpc.CallOption) error {
+		time.Sleep(1100 * time.Millisecond)
+		return nil
+	}
+
+	err := HystrixClientInterceptor()(
+		context.Background(),
+		"method",
+		nil,
+		nil,
+		nil,
+		invoker,
+	)
+
+	if !strings.Contains(err.Error(), hystrix.ErrTimeout.Error()) {
+		t.Errorf("hystrixInterceptor doesn't propagate the hystrix timeout error properly, got:%v", err)
+	}
+}
+
 func TestHystrixClientInterceptorOptionsCanIgnore(t *testing.T) {
 	err1 := errors.New("hello world")
 	tests := []struct {

interceptors/unary_interceptors.go

@@ -141,7 +141,7 @@ func HystrixClientInterceptor() grpc.UnaryClientInterceptor {
 		newCtx, cancel := context.WithCancel(ctx)
 		defer cancel()
 		var err error
-		_ = hystrix.Do(options.cmdName, func() (e error) {
+		herr := hystrix.Do(options.cmdName, func() (e error) {
 			defer func() {
 				if r := recover(); r != nil {
 					err = errors.Wrap(fmt.Errorf("panic inside hystrix Method: %s, req: %v, reply: %v", method, req, reply), "Hystrix")
@@ -157,7 +157,9 @@ func HystrixClientInterceptor() grpc.UnaryClientInterceptor {
 				return err
 			}
 		}, options.fallbackFunc)
-
+		if herr != nil {
+			return herr
+		}
 		return err
 	}
 }