Keep nested help commands with application handlers

execute_external_test.go

@@ -340,6 +340,61 @@ func TestExecuteHelpSkipsRequiredInputsAndRejectsNilContext(t *testing.T) {
 	}
 }
 
+func TestExecuteRunsApplicationOwnedNestedHelp(t *testing.T) {
+	type input struct{ topic commandkit.Supplied[string] }
+	var received []input
+	domainCause := errors.New("application help result")
+	help, err := commandkit.NewCommand(commandkit.CommandSpec[input]{
+		Name:        "help",
+		Description: "Explain a session topic.",
+		Arguments: []commandkit.Argument[input]{commandkit.ValueArgument(
+			commandkit.ArgumentMeta{Name: "TOPIC"}, true,
+			func(value string) (string, error) { return value, nil },
+			func(target *input, value commandkit.Supplied[string]) { target.topic = value },
+		)},
+		Run: func(_ commandkit.Invocation, value input) commandkit.Outcome {
+			received = append(received, value)
+			return commandkit.Domain("session-help", 7, domainCause)
+		},
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	session, err := commandkit.Group("session", "Session commands.", help)
+	if err != nil {
+		t.Fatal(err)
+	}
+	app, err := commandkit.New(commandkit.Identity{Name: "example"}, session)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	var diagnostic bytes.Buffer
+	outcome := app.Execute(context.Background(), []string{"session", "help", "restore"}, commandkit.Streams{Err: &diagnostic})
+	if outcome.Kind != commandkit.OutcomeDomain || outcome.Domain != "session-help" || outcome.Status != 7 || !errors.Is(outcome.Cause, domainCause) {
+		t.Fatalf("nested help handler outcome = %#v, diagnostics %q", outcome, diagnostic.String())
+	}
+	if len(received) != 1 || received[0].topic != (commandkit.Supplied[string]{Value: "restore", Set: true}) {
+		t.Fatalf("nested help handler input = %#v", received)
+	}
+
+	for _, args := range [][]string{{"session", "help", "--help"}, {"help", "session", "help"}} {
+		t.Run(strings.Join(args, " "), func(t *testing.T) {
+			var output, diagnostics bytes.Buffer
+			outcome := app.Execute(context.Background(), args, commandkit.Streams{Out: &output, Err: &diagnostics})
+			if outcome.Kind != commandkit.OutcomeSuccess || outcome.Status != 0 || diagnostics.Len() != 0 {
+				t.Fatalf("metadata help outcome = %#v, diagnostics %q", outcome, diagnostics.String())
+			}
+			if !strings.Contains(output.String(), "Explain a session topic.") || !strings.Contains(output.String(), "TOPIC") {
+				t.Fatalf("metadata help omitted nested command details: %q", output.String())
+			}
+			if len(received) != 1 {
+				t.Fatalf("metadata help invoked the application handler: %#v", received)
+			}
+		})
+	}
+}
+
 func TestHelpRendersRegisteredMetadataAndResolvesExactPaths(t *testing.T) {
 	type input struct {
 		count commandkit.Supplied[int]