marshal_jsonpb: Added nil slice default value

examples/integration/integration_test.go

@@ -1360,25 +1360,57 @@ func testResponseBodies(t *testing.T, port int) {
 }
 
 func testResponseStrings(t *testing.T, port int) {
-	url := fmt.Sprintf("http://localhost:%d/responsestrings/foo", port)
-	resp, err := http.Get(url)
-	if err != nil {
-		t.Errorf("http.Get(%q) failed with %v; want success", url, err)
-		return
-	}
-	defer resp.Body.Close()
-	buf, err := ioutil.ReadAll(resp.Body)
-	if err != nil {
-		t.Errorf("ioutil.ReadAll(resp.Body) failed with %v; want success", err)
-		return
-	}
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+	// Run Secondary server with different marshalling
+	ch := make(chan error)
+	go func() {
+		if err := runGateway(ctx, ":8081", runtime.WithMarshalerOption(runtime.MIMEWildcard, &runtime.JSONPb{EmitDefaults: true})); err != nil {
+			ch <- fmt.Errorf("cannot run gateway service: %v", err)
+		}
+	}()
 
-	if got, want := resp.StatusCode, http.StatusOK; got != want {
-		t.Errorf("resp.StatusCode = %d; want %d", got, want)
-		t.Logf("%s", buf)
-	}
+	port = 8081
 
-	if got, want := string(buf), `["hello","foo"]`; got != want {
-		t.Errorf("response = %q; want %q", got, want)
+	for i, spec := range []struct {
+		endpoint     string
+		expectedCode int
+		expectedBody string
+	}{
+		{
+			endpoint:     fmt.Sprintf("http://localhost:%d/responsestrings/foo", port),
+			expectedCode: http.StatusOK,
+			expectedBody: `["hello","foo"]`,
+		},
+		{
+			endpoint:     fmt.Sprintf("http://localhost:%d/responsestrings/empty", port),
+			expectedCode: http.StatusOK,
+			expectedBody: `[]`,
+		},
+	} {
+		t.Run(strconv.Itoa(i), func(t *testing.T) {
+			url := spec.endpoint
+			resp, err := http.Get(url)
+			if err != nil {
+				t.Errorf("http.Get(%q) failed with %v; want success", url, err)
+				return
+			}
+			defer resp.Body.Close()
+			buf, err := ioutil.ReadAll(resp.Body)
+			if err != nil {
+				t.Errorf("ioutil.ReadAll(resp.Body) failed with %v; want success", err)
+				return
+			}
+
+			if got, want := resp.StatusCode, spec.expectedCode; got != want {
+				t.Errorf("resp.StatusCode = %d; want %d", got, want)
+				t.Logf("%s", buf)
+			}
+
+			if got, want := string(buf), spec.expectedBody; got != want {
+				t.Errorf("response = %q; want %q", got, want)
+			}
+		})
 	}
+
 }

examples/server/responsebody.go

@@ -33,6 +33,11 @@ func (s *responseBodyServer) ListResponseBodies(ctx context.Context, req *exampl
 }
 
 func (s *responseBodyServer) ListResponseStrings(ctx context.Context, req *examples.ResponseBodyIn) (*examples.RepeatedResponseStrings, error) {
+	if req.Data == "empty" {
+		return &examples.RepeatedResponseStrings{
+			Values: []string{},
+		}, nil
+	}
 	return &examples.RepeatedResponseStrings{
 		Values: []string{"hello", req.Data},
 	}, nil

runtime/marshal_jsonpb.go

@@ -67,6 +67,10 @@ func (j *JSONPb) marshalNonProtoField(v interface{}) ([]byte, error) {
 		rv = rv.Elem()
 	}
 
+	if rv.Kind() == reflect.Slice && rv.IsNil() && j.EmitDefaults {
+		return []byte("[]"), nil
+	}
+
 	if rv.Kind() == reflect.Map {
 		m := make(map[string]*json.RawMessage)
 		for _, k := range rv.MapKeys() {

runtime/marshal_jsonpb_test.go

@@ -3,6 +3,7 @@ package runtime_test
 import (
 	"bytes"
 	"reflect"
+	"strconv"
 	"strings"
 	"testing"
 
@@ -614,3 +615,132 @@ var (
 		// TODO(yugui) Add other well-known types once jsonpb supports them
 	}
 )
+
+func TestJSONPbMarshalResponseBodies(t *testing.T) {
+	for i, spec := range []struct {
+		input        interface{}
+		emitDefaults bool
+		verifier     func(json string)
+	}{
+		{
+			input: &examplepb.ResponseBodyOut{
+				Response: &examplepb.ResponseBodyOut_Response{Data: "abcdef"},
+			},
+			verifier: func(json string) {
+				expected := `{"response":{"data":"abcdef"}}`
+				if json != expected {
+					t.Errorf("json not equal (%q, %q)", json, expected)
+				}
+			},
+		},
+		{
+			emitDefaults: true,
+			input:        &examplepb.ResponseBodyOut{},
+			verifier: func(json string) {
+				expected := `{"response":null}`
+				if json != expected {
+					t.Errorf("json not equal (%q, %q)", json, expected)
+				}
+			},
+		},
+		{
+			input: &examplepb.RepeatedResponseBodyOut_Response{},
+			verifier: func(json string) {
+				expected := `{}`
+				if json != expected {
+					t.Errorf("json not equal (%q, %q)", json, expected)
+				}
+			},
+		},
+		{
+			emitDefaults: true,
+			input:        &examplepb.RepeatedResponseBodyOut_Response{},
+			verifier: func(json string) {
+				expected := `{"data":""}`
+				if json != expected {
+					t.Errorf("json not equal (%q, %q)", json, expected)
+				}
+			},
+		},
+		{
+			input: ([]*examplepb.RepeatedResponseBodyOut_Response)(nil),
+			verifier: func(json string) {
+				expected := `null`
+				if json != expected {
+					t.Errorf("json not equal (%q, %q)", json, expected)
+				}
+			},
+		},
+		{
+			emitDefaults: true,
+			input:        ([]*examplepb.RepeatedResponseBodyOut_Response)(nil),
+			verifier: func(json string) {
+				expected := `[]`
+				if json != expected {
+					t.Errorf("json not equal (%q, %q)", json, expected)
+				}
+			},
+		},
+		{
+			input: []*examplepb.RepeatedResponseBodyOut_Response{},
+			verifier: func(json string) {
+				expected := `[]`
+				if json != expected {
+					t.Errorf("json not equal (%q, %q)", json, expected)
+				}
+			},
+		},
+		{
+			input: []string{"something"},
+			verifier: func(json string) {
+				expected := `["something"]`
+				if json != expected {
+					t.Errorf("json not equal (%q, %q)", json, expected)
+				}
+			},
+		},
+		{
+			input: []string{},
+			verifier: func(json string) {
+				expected := `[]`
+				if json != expected {
+					t.Errorf("json not equal (%q, %q)", json, expected)
+				}
+			},
+		},
+		{
+			input: ([]string)(nil),
+			verifier: func(json string) {
+				expected := `null`
+				if json != expected {
+					t.Errorf("json not equal (%q, %q)", json, expected)
+				}
+			},
+		},
+		{
+			emitDefaults: true,
+			input:        ([]string)(nil),
+			verifier: func(json string) {
+				expected := `[]`
+				if json != expected {
+					t.Errorf("json not equal (%q, %q)", json, expected)
+				}
+			},
+		},
+	} {
+
+		t.Run(strconv.Itoa(i), func(t *testing.T) {
+			m := runtime.JSONPb{
+				EmitDefaults: spec.emitDefaults,
+			}
+			val := spec.input
+			buf, err := m.Marshal(val)
+			if err != nil {
+				t.Errorf("m.Marshal(%v) failed with %v; want success; spec=%v", val, err, spec)
+			}
+			if spec.verifier != nil {
+				spec.verifier(string(buf))
+			}
+		})
+	}
+}