fix: chanResponseEmitter cancel being ineffective

Author: djdv

chan.go

@@ -96,6 +96,10 @@ func (r *chanResponse) Next() (interface{}, error) {
 		ctx = context.Background()
 	}
 
+	if err := ctx.Err(); err != nil {
+		return nil, err
+	}
+
 	select {
 	case v, ok := <-r.ch:
 		if !ok {
@@ -145,6 +149,10 @@ func (re *chanResponseEmitter) Emit(v interface{}) error {
 
 	ctx := re.req.Context
 
+	if err := ctx.Err(); err != nil {
+		return err
+	}
+
 	select {
 	case re.ch <- v:
 		if _, ok := v.(Single); ok {

command_test.go

@@ -316,6 +316,7 @@ func TestCancel(t *testing.T) {
 	}
 
 	re, res := NewChanResponsePair(req)
+	cancel()
 
 	go func() {
 		err := re.Emit("abc")
@@ -328,8 +329,6 @@ func TestCancel(t *testing.T) {
 		close(wait)
 	}()
 
-	cancel()
-
 	_, err = res.Next()
 	if err != context.Canceled {
 		t.Errorf("res: expected context.Canceled but got %v", err)