encoding/xml: format test output using subtests

Change-Id: I2d155c838935cd8427abd142a462ff4c56829715
Reviewed-on: https://go-review.googlesource.com/37948Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/encoding/xml/marshal_test.go

@@ -1652,28 +1652,31 @@ func TestMarshal(t *testing.T) {
 		if test.UnmarshalOnly {
 			continue
 		}
+
+		t.Run(fmt.Sprintf("%d", idx), func(t *testing.T) {
 			data, err := Marshal(test.Value)
 			if err != nil {
 				if test.MarshalError == "" {
-				t.Errorf("#%d: marshal(%#v): %s", idx, test.Value, err)
-				continue
+					t.Errorf("marshal(%#v): %s", test.Value, err)
+					return
 				}
 				if !strings.Contains(err.Error(), test.MarshalError) {
-				t.Errorf("#%d: marshal(%#v): %s, want %q", idx, test.Value, err, test.MarshalError)
+					t.Errorf("marshal(%#v): %s, want %q", test.Value, err, test.MarshalError)
 				}
-			continue
+				return
 			}
 			if test.MarshalError != "" {
-			t.Errorf("#%d: Marshal succeeded, want error %q", idx, test.MarshalError)
-			continue
+				t.Errorf("Marshal succeeded, want error %q", test.MarshalError)
+				return
 			}
 			if got, want := string(data), test.ExpectXML; got != want {
 				if strings.Contains(want, "\n") {
-				t.Errorf("#%d: marshal(%#v):\nHAVE:\n%s\nWANT:\n%s", idx, test.Value, got, want)
+					t.Errorf("marshal(%#v):\nHAVE:\n%s\nWANT:\n%s", test.Value, got, want)
 				} else {
-				t.Errorf("#%d: marshal(%#v):\nhave %#q\nwant %#q", idx, test.Value, got, want)
+					t.Errorf("marshal(%#v):\nhave %#q\nwant %#q", test.Value, got, want)
 				}
 			}
+		})
 	}
 }
 
@@ -1781,6 +1784,7 @@ func TestUnmarshal(t *testing.T) {
 		dest := reflect.New(vt.Elem()).Interface()
 		err := Unmarshal([]byte(test.ExpectXML), dest)
 
+		t.Run(fmt.Sprintf("%d", i), func(t *testing.T) {
 			switch fix := dest.(type) {
 			case *Feed:
 				fix.Author.InnerXML = ""
@@ -1791,17 +1795,18 @@ func TestUnmarshal(t *testing.T) {
 
 			if err != nil {
 				if test.UnmarshalError == "" {
-				t.Errorf("#%d: unmarshal(%#v): %s", i, test.ExpectXML, err)
-				continue
+					t.Errorf("unmarshal(%#v): %s", test.ExpectXML, err)
+					return
 				}
 				if !strings.Contains(err.Error(), test.UnmarshalError) {
-				t.Errorf("#%d: unmarshal(%#v): %s, want %q", i, test.ExpectXML, err, test.UnmarshalError)
+					t.Errorf("unmarshal(%#v): %s, want %q", test.ExpectXML, err, test.UnmarshalError)
 				}
-			continue
+				return
 			}
 			if got, want := dest, test.Value; !reflect.DeepEqual(got, want) {
-			t.Errorf("#%d: unmarshal(%q):\nhave %#v\nwant %#v", i, test.ExpectXML, got, want)
+				t.Errorf("unmarshal(%q):\nhave %#v\nwant %#v", test.ExpectXML, got, want)
 			}
+		})
 	}
 }