1// Copyright 2020 The Go Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4
5package fs_test
6
7import (
8	"errors"
9	. "io/fs"
10	"testing"
11)
12
13type subOnly struct{ SubFS }
14
15func (subOnly) Open(name string) (File, error) { return nil, ErrNotExist }
16
17func TestSub(t *testing.T) {
18	check := func(desc string, sub FS, err error) {
19		t.Helper()
20		if err != nil {
21			t.Errorf("Sub(sub): %v", err)
22			return
23		}
24		data, err := ReadFile(sub, "goodbye.txt")
25		if string(data) != "goodbye, world" || err != nil {
26			t.Errorf(`ReadFile(%s, "goodbye.txt" = %q, %v, want %q, nil`, desc, string(data), err, "goodbye, world")
27		}
28
29		dirs, err := ReadDir(sub, ".")
30		if err != nil || len(dirs) != 1 || dirs[0].Name() != "goodbye.txt" {
31			var names []string
32			for _, d := range dirs {
33				names = append(names, d.Name())
34			}
35			t.Errorf(`ReadDir(%s, ".") = %v, %v, want %v, nil`, desc, names, err, []string{"goodbye.txt"})
36		}
37	}
38
39	// Test that Sub uses the method when present.
40	sub, err := Sub(subOnly{testFsys}, "sub")
41	check("subOnly", sub, err)
42
43	// Test that Sub uses Open when the method is not present.
44	sub, err = Sub(openOnly{testFsys}, "sub")
45	check("openOnly", sub, err)
46
47	_, err = sub.Open("nonexist")
48	if err == nil {
49		t.Fatal("Open(nonexist): succeeded")
50	}
51	pe, ok := err.(*PathError)
52	if !ok {
53		t.Fatalf("Open(nonexist): error is %T, want *PathError", err)
54	}
55	if pe.Path != "nonexist" {
56		t.Fatalf("Open(nonexist): err.Path = %q, want %q", pe.Path, "nonexist")
57	}
58
59	_, err = sub.Open("./")
60	if !errors.Is(err, ErrInvalid) {
61		t.Fatalf("Open(./): error is %v, want %v", err, ErrInvalid)
62	}
63}
64