feat(helm): warn on 'helm list' truncation with default --max limit

add a stderr warning when results are truncated by the default --max limit.

Closes #31617

Signed-off-by: John Weathers <weathers.johnb@gmail.com>

pkg/action/list.go

@@ -135,6 +135,8 @@ type List struct {
 	Failed       bool
 	Pending      bool
 	Selector     string
+	// Truncated indicates results were omitted due to Limit
+	Truncated bool
 }
 
 // NewList constructs a new *List
@@ -213,7 +215,7 @@ func (l *List) Run() ([]ri.Releaser, error) {
 	}
 
 	// Calculate the limit and offset, and then truncate results if necessary.
-	limit := len(results)
+	limit := len(rresults)
 	if l.Limit > 0 && l.Limit < limit {
 		limit = l.Limit
 	}
@@ -221,6 +223,8 @@ func (l *List) Run() ([]ri.Releaser, error) {
 	if l := len(rresults); l < last {
 		last = l
 	}
+	l.Truncated = last < len(rresults)
+
 	rresults = rresults[l.Offset:last]
 
 	return releaseV1ListToReleaserList(rresults)

pkg/action/list_test.go

@@ -175,6 +175,55 @@ func TestList_LimitOffsetOutOfBounds(t *testing.T) {
 	is.Len(list, 2)
 }
 
+func TestList_Truncation(t *testing.T) {
+	is := assert.New(t)
+	// Create 3 releases
+	lister := newListFixture(t)
+	makeMeSomeReleases(t, lister.cfg.Releases)
+
+	lister.Limit = 5
+	lister.Offset = 0
+	list, err := lister.Run()
+	is.NoError(err)
+	is.Len(list, 3)
+	is.False(lister.Truncated, "Expected Truncated to be false when limit > total")
+
+	lister.Limit = 3
+	lister.Offset = 0
+	list, err = lister.Run()
+	is.NoError(err)
+	is.Len(list, 3)
+	is.False(lister.Truncated, "Expected Truncated to be false when limit == total")
+
+	lister.Limit = 2
+	lister.Offset = 0
+	list, err = lister.Run()
+	is.NoError(err)
+	is.Len(list, 2)
+	is.True(lister.Truncated, "Expected Truncated to be true when limit < total")
+
+	lister.Limit = 1
+	lister.Offset = 1
+	list, err = lister.Run()
+	is.NoError(err)
+	is.Len(list, 1)
+	is.True(lister.Truncated, "Expected Truncated to be true when offset + limit < total")
+
+	lister.Limit = 1
+	lister.Offset = 2
+	list, err = lister.Run()
+	is.NoError(err)
+	is.Len(list, 1)
+	is.False(lister.Truncated, "Expected Truncated to be false when offset + limit == total")
+
+	lister.Limit = 1
+	lister.Offset = 3
+	list, err = lister.Run()
+	is.NoError(err)
+	is.Len(list, 0)
+	is.False(lister.Truncated, "Expected Truncated to be false when offset >= total")
+}
+
 func TestList_StateMask(t *testing.T) {
 	is := assert.New(t)
 	lister := newListFixture(t)

pkg/cmd/list.go

@@ -113,7 +113,16 @@ func newListCmd(cfg *action.Configuration, out io.Writer) *cobra.Command {
 				}
 			}
 
-			return outfmt.Write(out, newReleaseListWriter(results, client.TimeFormat, client.NoHeaders, settings.ShouldDisableColor()))
+			if err := outfmt.Write(out, newReleaseListWriter(results, client.TimeFormat, client.NoHeaders, settings.ShouldDisableColor())); err != nil {
+				return err
+			}
+
+			outputFlag := cmd.Flag("output")
+			if outputFlag.Value.String() == "table" && client.Truncated && !cmd.Flags().Changed("max") {
+				fmt.Fprintln(os.Stderr, "WARNING: results were truncated due to the default --max limit. Use --max to show more releases.")
+			}
+
+			return nil
 		},
 	}