sub_test.go

Documentation: io/fs

     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  	"errors"
     9  	. "io/fs"
    10  	"testing"
    11  )
    12  
    13  type subOnly struct{ SubFS }
    14  
    15  func (subOnly) Open(name string) (File, error) { return nil, ErrNotExist }
    16  
    17  func 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
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