metadata: add checks for nil context

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>

metadata/metadata.go

@@ -84,6 +84,9 @@ func Get(ctx context.Context, key string) (string, bool) {
 
 // FromContext returns metadata from the given context
 func FromContext(ctx context.Context) (Metadata, bool) {
+	if ctx == nil {
+		return nil, false
+	}
 	md, ok := ctx.Value(metadataKey{}).(Metadata)
 	if !ok {
 		return nil, ok
@@ -102,6 +105,9 @@ func New(size int) Metadata {
 
 // NewContext creates a new context with the given metadata
 func NewContext(ctx context.Context, md Metadata) context.Context {
+	if ctx == nil {
+		ctx = context.Background()
+	}
 	return context.WithValue(ctx, metadataKey{}, Copy(md))
 }
 

metadata/metadata_test.go

@@ -63,6 +63,15 @@ func TestMetadataDelete(t *testing.T) {
 
 }
 
+func TestNilContext(t *testing.T) {
+	var ctx context.Context
+
+	_, ok := FromContext(ctx)
+	if ok {
+		t.Fatal("nil context")
+	}
+}
+
 func TestMetadataCopy(t *testing.T) {
 	md := Metadata{
 		"Foo": "bar",