feat: trigger breaker on underlying service timeout (#4112)

zrpc/internal/serverinterceptors/breakerinterceptor_test.go

@@ -29,6 +29,15 @@ func TestUnaryBreakerInterceptor(t *testing.T) {
 	assert.NotNil(t, err)
 }
 
+func TestUnaryBreakerInterceptorOK(t *testing.T) {
+	_, err := UnaryBreakerInterceptor(context.Background(), nil, &grpc.UnaryServerInfo{
+		FullMethod: "any",
+	}, func(_ context.Context, _ any) (any, error) {
+		return nil, nil
+	})
+	assert.NoError(t, err)
+}
+
 func TestUnaryBreakerInterceptor_Unavailable(t *testing.T) {
 	_, err := UnaryBreakerInterceptor(context.Background(), nil, &grpc.UnaryServerInfo{
 		FullMethod: "any",
@@ -36,4 +45,37 @@ func TestUnaryBreakerInterceptor_Unavailable(t *testing.T) {
 		return nil, breaker.ErrServiceUnavailable
 	})
 	assert.NotNil(t, err)
+	code := status.Code(err)
+	assert.Equal(t, codes.Unavailable, code)
+}
+
+func TestUnaryBreakerInterceptor_Deadline(t *testing.T) {
+	for i := 0; i < 1000; i++ {
+		_, err := UnaryBreakerInterceptor(context.Background(), nil, &grpc.UnaryServerInfo{
+			FullMethod: "any",
+		}, func(_ context.Context, _ any) (any, error) {
+			return nil, context.DeadlineExceeded
+		})
+		switch status.Code(err) {
+		case codes.Unavailable:
+		default:
+			assert.Equal(t, context.DeadlineExceeded, err)
+		}
+	}
+
+	var dropped bool
+	for i := 0; i < 100; i++ {
+		_, err := UnaryBreakerInterceptor(context.Background(), nil, &grpc.UnaryServerInfo{
+			FullMethod: "any",
+		}, func(_ context.Context, _ any) (any, error) {
+			return nil, context.DeadlineExceeded
+		})
+		switch status.Code(err) {
+		case codes.Unavailable:
+			dropped = true
+		default:
+			assert.Equal(t, context.DeadlineExceeded, err)
+		}
+	}
+	assert.True(t, dropped)
 }