Reuse adapter sessions during execution

parser_test.go

@@ -53,6 +53,48 @@ func TestAppParseUsesRegisteredBindingsWithTheAdapter(t *testing.T) {
 	}
 }
 
+func TestExecutionRefreshesHelpMetadataAfterRegistration(t *testing.T) {
+	first, err := NewCommand(CommandSpec[struct{}]{
+		Name: "first",
+		Run:  func(Invocation, struct{}) Outcome { return Success() },
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	app, err := New(Identity{Name: "example"}, first)
+	if err != nil {
+		t.Fatal(err)
+	}
+	var output bytes.Buffer
+	current := newExecution(app, context.Background(), Streams{Out: &output, Err: io.Discard})
+	parsed := current.parse([]string{"first"})
+	if parsed.Failure != nil {
+		t.Fatalf("initial parse failed: %s", parsed.Failure.Message)
+	}
+
+	late, err := NewCommand(CommandSpec[struct{}]{
+		Name:    "late",
+		Summary: "registered during execution",
+		Run:     func(Invocation, struct{}) Outcome { return Success() },
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := app.Register(late); err != nil {
+		t.Fatal(err)
+	}
+
+	if got := current.renderHelp([]string{"late"}); got.Kind != OutcomeSuccess {
+		t.Fatalf("help after registration = %#v", got)
+	}
+	if !strings.Contains(output.String(), "registered during execution") {
+		t.Fatalf("help did not use registered metadata: %q", output.String())
+	}
+	if got := current.usageLine([]string{"late"}); !strings.HasPrefix(got, "Usage: example late") {
+		t.Fatalf("usage after registration = %q", got)
+	}
+}
+
 func TestBridgeTreeRefreshesAfterSuccessfulRegistration(t *testing.T) {
 	app, err := New(Identity{Name: "example"})
 	if err != nil {