t.Errorf("ParseGlob: %v\nwanted error about already having Executed", err)
	}
	if _, err := c.root.AddParseTree("t1", c.root.Tree); err == nil || !strings.Contains(err.Error(), "Execute") {
		t.Errorf("AddParseTree: %v\nwanted error about already having Executed", err)
	}
}

func TestNumbers(t *testing.T) {
	c := newTestCase(t)

		rightDelim: t.rightDelim,
	}
}

// AddParseTree associates the argument parse tree with the template t, giving
// it the specified name. If the template has not been defined, this tree becomes
// its definition. If it has been defined and already has that name, the existing
// definition is replaced; otherwise a new template is created, defined, and returned.
func (t *Template) AddParseTree(name string, tree *parse.Tree) (*Template, error) {

	}

	// Define a named template with specified contents.
	def := func(name, contents string) {
		sub := template.New(name)
		template.Must(sub.Parse(contents))
		template.Must(templates.AddParseTree(name, sub.Tree))
	}

	// Embedded files.
	def("css", loadCSS("html/common.css"))
	def("header", loadFile("html/header.html"))
	def("graph", loadFile("html/graph.html"))
	def("graph_css", loadCSS("html/graph.css"))

	tmpl := New("master")
	tree, err := parse.Parse("master", master, "", "", nil)
	if err != nil {
		t.Fatalf("unexpected parse err: %v", err)
	}
	masterTree := tree["master"]
	tmpl.AddParseTree("master", masterTree) // used to panic
}

func TestRedefinition(t *testing.T) {
	var tmpl *Template
	var err error
	if tmpl, err = New("tmpl1").Parse(`{{define "test"}}foo{{end}}`); err != nil {

	tree, err := parse.Parse("t", `{{define "b"}}<a href="{{end}}`, "", "", nil, nil)
	if err != nil {
		t.Fatal(err)
	}
	added := Must(root.AddParseTree("b", tree["b"]))
	b := new(strings.Builder)
	err = added.ExecuteTemplate(b, "a", "1>0")
	if err != nil {
		t.Fatal(err)
	}
	if got, want := b.String(), ` 1&gt;0 <a href=" 1%3e0 "></a>`; got != want {