fix(helm): add test for repo update strict flag

While adding the test, noticed a race in the repo update code, due to
multiple go routines potentially incrementing the error counter.
Included the required mutex in the repo update code in the same commit,
since the new test uncovered the race condition.

Signed-off-by: Arash Deshmeh <adeshmeh@ca.ibm.com>

cmd/helm/repo_update.go

@@ -93,21 +93,28 @@ func updateCharts(repos []*repo.ChartRepository, out io.Writer, home helmpath.Ho
 	var (
 		errorCounter int
 		wg           sync.WaitGroup
+		mu           sync.Mutex
 	)
 	for _, re := range repos {
 		wg.Add(1)
 		go func(re *repo.ChartRepository) {
 			defer wg.Done()
 			if re.Config.Name == localRepository {
+				mu.Lock()
 				fmt.Fprintf(out, "...Skip %s chart repository\n", re.Config.Name)
+				mu.Unlock()
 				return
 			}
 			err := re.DownloadIndexFile(home.Cache())
 			if err != nil {
+				mu.Lock()
 				errorCounter++
 				fmt.Fprintf(out, "...Unable to get an update from the %q chart repository (%s):\n\t%s\n", re.Config.Name, re.Config.URL, err)
+				mu.Unlock()
 			} else {
+				mu.Lock()
 				fmt.Fprintf(out, "...Successfully got an update from the %q chart repository\n", re.Config.Name)
+				mu.Unlock()
 			}
 		}(re)
 	}

cmd/helm/repo_update_test.go

@@ -105,3 +105,30 @@ func TestUpdateCharts(t *testing.T) {
 		t.Error("Update was not successful")
 	}
 }
+
+func TestUpdateCmdStrictFlag(t *testing.T) {
+	thome, err := tempHelmHome(t)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	cleanup := resetEnv()
+	defer func() {
+		os.RemoveAll(thome.String())
+		cleanup()
+	}()
+
+	settings.Home = thome
+
+	out := bytes.NewBuffer(nil)
+	cmd := newRepoUpdateCmd(out)
+	cmd.ParseFlags([]string{"--strict"})
+
+	if err := cmd.RunE(cmd, []string{}); err == nil {
+		t.Fatal("expected error due to strict flag")
+	}
+
+	if got := out.String(); !strings.Contains(got, "Unable to get an update") {
+		t.Errorf("Expected 'Unable to get an update', got %q", got)
+	}
+}