Method TestOutgoingCarrier

stats/opentelemetry/internal/tracing/carrier_test.go:133–190

TestOutgoingCarrier verifies that a key-value pair is set in carrier's context metadata using `OutgoingCarrier.Set()`. If key is not present, it verifies that key-value pair is insterted. If key is already present, it verifies that new value is appended at the end of list for the existing key. If k

(t *testing.T)

// It also verifies that both existing and newly inserted keys are present in
// the carrier's context using `Carrier.Keys()`.
func (s) TestOutgoingCarrier(t *testing.T) {
	tests := []struct {
		name      string
		initialMD metadata.MD
		setKey    string
		setValue  string
		wantValue string // expected value of the set key
		wantKeys  []string
	}{
		{
			name:      "new key",
			initialMD: metadata.MD{},
			setKey:    "key1",
			setValue:  "value1",
			wantValue: "value1",
			wantKeys:  []string{"key1"},
		},
		{
			name:      "add to existing key",
			initialMD: metadata.MD{"key1": []string{"oldvalue"}},
			setKey:    "key1",
			setValue:  "newvalue",
			wantValue: "newvalue",
			wantKeys:  []string{"key1"},
		},
		{
			name:      "new key with different existing key",
			initialMD: metadata.MD{"key2": []string{"value2"}},
			setKey:    "key1",
			setValue:  "value1",
			wantValue: "value1",
			wantKeys:  []string{"key2", "key1"},
		},
		{
			name:      "grpc-trace-bin binary key",
			initialMD: metadata.MD{"key1": []string{"value1"}},
			setKey:    "grpc-trace-bin",
			setValue:  string([]byte{0x01, 0x02, 0x03}),
			wantValue: string([]byte{0x01, 0x02, 0x03}),
			wantKeys:  []string{"key1", "grpc-trace-bin"},
		},
	}

	for _, test := range tests {
		t.Run(test.name, func(t *testing.T) {
			ctx, cancel := context.WithCancel(context.Background())
			defer cancel()
			c := NewOutgoingCarrier(metadata.NewOutgoingContext(ctx, test.initialMD))
			c.Set(test.setKey, test.setValue)
			if gotKeys := c.Keys(); !cmp.Equal(test.wantKeys, gotKeys, cmpopts.SortSlices(func(a, b string) bool { return a < b })) {
				t.Fatalf("c.Keys() = keys %v, want %v", gotKeys, test.wantKeys)
			}
			if md, ok := metadata.FromOutgoingContext(c.Context()); ok && md.Get(test.setKey)[len(md.Get(test.setKey))-1] != test.wantValue {
				t.Fatalf("got value %s, want %s, for key %s", md.Get(test.setKey)[len(md.Get(test.setKey))-1], test.wantValue, test.setKey)
			}
		})
	}
}