github.com/twelsh-aw/go/src@v0.0.0-20230516233729-a56fe86a7c81/io/fs/sub_test.go (about)

     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  
     5  package fs_test
     6  
     7  import (
     8  	. "io/fs"
     9  	"testing"
    10  )
    11  
    12  type subOnly struct{ SubFS }
    13  
    14  func (subOnly) Open(name string) (File, error) { return nil, ErrNotExist }
    15  
    16  func TestSub(t *testing.T) {
    17  	check := func(desc string, sub FS, err error) {
    18  		t.Helper()
    19  		if err != nil {
    20  			t.Errorf("Sub(sub): %v", err)
    21  			return
    22  		}
    23  		data, err := ReadFile(sub, "goodbye.txt")
    24  		if string(data) != "goodbye, world" || err != nil {
    25  			t.Errorf(`ReadFile(%s, "goodbye.txt" = %q, %v, want %q, nil`, desc, string(data), err, "goodbye, world")
    26  		}
    27  
    28  		dirs, err := ReadDir(sub, ".")
    29  		if err != nil || len(dirs) != 1 || dirs[0].Name() != "goodbye.txt" {
    30  			var names []string
    31  			for _, d := range dirs {
    32  				names = append(names, d.Name())
    33  			}
    34  			t.Errorf(`ReadDir(%s, ".") = %v, %v, want %v, nil`, desc, names, err, []string{"goodbye.txt"})
    35  		}
    36  	}
    37  
    38  	// Test that Sub uses the method when present.
    39  	sub, err := Sub(subOnly{testFsys}, "sub")
    40  	check("subOnly", sub, err)
    41  
    42  	// Test that Sub uses Open when the method is not present.
    43  	sub, err = Sub(openOnly{testFsys}, "sub")
    44  	check("openOnly", sub, err)
    45  
    46  	_, err = sub.Open("nonexist")
    47  	if err == nil {
    48  		t.Fatal("Open(nonexist): succeeded")
    49  	}
    50  	pe, ok := err.(*PathError)
    51  	if !ok {
    52  		t.Fatalf("Open(nonexist): error is %T, want *PathError", err)
    53  	}
    54  	if pe.Path != "nonexist" {
    55  		t.Fatalf("Open(nonexist): err.Path = %q, want %q", pe.Path, "nonexist")
    56  	}
    57  }