func print(t *testing.T, name string, f *ast.File) string {
var buf bytes.Buffer
if err := format.Node(&buf, fset, f); err != nil {
t.Fatalf("%s gofmt: %v", name, err)
}
return string(buf.Bytes())
}
func TestExamples(t *testing.T) {
fset := token.NewFileSet()
file, err := parser.ParseFile(fset, "test.go", strings.NewReader(exampleTestFile), parser.ParseComments)
if err != nil {
t.Fatal(err)
}
for i, e := range doc.Examples(file) {
c := exampleTestCases[i]
if e.Name != c.Name {
t.Errorf("got Name == %q, want %q", e.Name, c.Name)
}
if w := c.Play; w != "" {
var g string // hah
if e.Play == nil {
g = "<nil>"
} else {
var buf bytes.Buffer
if err := format.Node(&buf, fset, e.Play); err != nil {
t.Fatal(err)
}
g = buf.String()
}
if g != w {
t.Errorf("%s: got Play == %q, want %q", c.Name, g, w)
}
}
if g, w := e.Output, c.Output; g != w {
t.Errorf("%s: got Output == %q, want %q", c.Name, g, w)
}
}
}
func TestFilterDuplicates(t *testing.T) {
// parse input
fset := token.NewFileSet()
file, err := parser.ParseFile(fset, "", input, 0)
if err != nil {
t.Fatal(err)
}
// create package
files := map[string]*ast.File{"": file}
pkg, err := ast.NewPackage(fset, files, nil, nil)
if err != nil {
t.Fatal(err)
}
// filter
merged := ast.MergePackageFiles(pkg, ast.FilterFuncDuplicates)
// pretty-print
var buf bytes.Buffer
if err := format.Node(&buf, fset, merged); err != nil {
t.Fatal(err)
}
output := buf.String()
if output != golden {
t.Errorf("incorrect output:\n%s", output)
}
}
// This example illustrates how to remove a variable declaration
// in a Go program while maintaining correct comment association
// using an ast.CommentMap.
func ExampleCommentMap() {
// src is the input for which we create the AST that we
// are going to manipulate.
src := `
// This is the package comment.
package main
// This comment is associated with the hello constant.
const hello = "Hello, World!" // line comment 1
// This comment is associated with the foo variable.
var foo = hello // line comment 2
// This comment is associated with the main function.
func main() {
fmt.Println(hello) // line comment 3
}
`
// Create the AST by parsing src.
fset := token.NewFileSet() // positions are relative to fset
f, err := parser.ParseFile(fset, "src.go", src, parser.ParseComments)
if err != nil {
panic(err)
}
// Create an ast.CommentMap from the ast.File's comments.
// This helps keeping the association between comments
// and AST nodes.
cmap := ast.NewCommentMap(fset, f, f.Comments)
// Remove the first variable declaration from the list of declarations.
f.Decls = removeFirstVarDecl(f.Decls)
// Use the comment map to filter comments that don't belong anymore
// (the comments associated with the variable declaration), and create
// the new comments list.
f.Comments = cmap.Filter(f).Comments()
// Print the modified AST.
var buf bytes.Buffer
if err := format.Node(&buf, fset, f); err != nil {
panic(err)
}
fmt.Printf("%s", buf.Bytes())
// output:
// // This is the package comment.
// package main
//
// // This comment is associated with the hello constant.
// const hello = "Hello, World!" // line comment 1
//
// // This comment is associated with the main function.
// func main() {
// fmt.Println(hello) // line comment 3
// }
}
func exprString(fset *token.FileSet, expr ast.Expr) string {
var buf bytes.Buffer
format.Node(&buf, fset, expr)
return buf.String()
}