// TODO above.
	var multiplePackageError *build.MultiplePackageError
	var noGoError *build.NoGoError
	if err != nil {
		if errors.As(err, &noGoError) {
			return // No source files in this package are built. Skip embeds in ignored files.
		} else if !errors.As(err, &multiplePackageError) { // multiplePackageErrors are OK, but others are not.

# CL 155050043 go/build: Return MultiplePackageError on importing a dir containing multiple packages, Jens Frederich <******@****.***>
pkg go/build, method (*MultiplePackageError) Error() string
pkg go/build, type MultiplePackageError struct
pkg go/build, type MultiplePackageError struct, Dir string
pkg go/build, type MultiplePackageError struct, Files []string

	}
}

func TestMultiplePackageImport(t *testing.T) {
	pkg, err := Import(".", "testdata/multi", 0)

	mpe, ok := err.(*MultiplePackageError)
	if !ok {
		t.Fatal(`Import("testdata/multi") did not return MultiplePackageError.`)
	}
	want := &MultiplePackageError{
		Dir:      filepath.FromSlash("testdata/multi"),
		Packages: []string{"main", "test_package"},
		Files:    []string{"file.go", "file_appengine.go"},

}

// MultiplePackageError describes a directory containing
// multiple buildable Go source files for multiple packages.
type MultiplePackageError struct {
	Dir      string   // directory containing files
	Packages []string // package names found
	Files    []string // corresponding files: Files[i] declares package Packages[i]
}

func (e *MultiplePackageError) Error() string {

}

// MultiplePackageError describes a directory containing
// multiple buildable Go source files for multiple packages.
type MultiplePackageError struct {
	Dir      string   // directory containing files
	Packages []string // package names found
	Files    []string // corresponding files: Files[i] declares package Packages[i]
}

func (e *MultiplePackageError) Error() string {

			// order. Instead of resolving p.Name arbitrarily, we should clear out the
			// existing Name and mark the existing files as also invalid.
			badGoFile(name, &MultiplePackageError{
				Dir:      p.Dir,
				Packages: []string{p.Name, pkg},
				Files:    []string{firstFile, name},
			})
		}
		// Grab the first package comment as docs, provided it is not from a test file.

		{"ImportComment", Const, 4},
		{"ImportDir", Func, 0},
		{"ImportMode", Type, 0},
		{"IsLocalImport", Func, 0},
		{"MultiplePackageError", Type, 4},
		{"MultiplePackageError.Dir", Field, 4},
		{"MultiplePackageError.Files", Field, 4},
		{"MultiplePackageError.Packages", Field, 4},
		{"NoGoError", Type, 0},
		{"NoGoError.Dir", Field, 0},
		{"Package", Type, 0},
		{"Package.AllTags", Field, 2},