github.com/geraldss/go/src@v0.0.0-20210511222824-ac7d0ebfc235/io/fs/readfile_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  	"testing/fstest"
    11  	"time"
    12  )
    13  
    14  var testFsys = fstest.MapFS{
    15  	"hello.txt": {
    16  		Data:    []byte("hello, world"),
    17  		Mode:    0456,
    18  		ModTime: time.Now(),
    19  		Sys:     &sysValue,
    20  	},
    21  	"sub/goodbye.txt": {
    22  		Data:    []byte("goodbye, world"),
    23  		Mode:    0456,
    24  		ModTime: time.Now(),
    25  		Sys:     &sysValue,
    26  	},
    27  }
    28  
    29  var sysValue int
    30  
    31  type readFileOnly struct{ ReadFileFS }
    32  
    33  func (readFileOnly) Open(name string) (File, error) { return nil, ErrNotExist }
    34  
    35  type openOnly struct{ FS }
    36  
    37  func TestReadFile(t *testing.T) {
    38  	// Test that ReadFile uses the method when present.
    39  	data, err := ReadFile(readFileOnly{testFsys}, "hello.txt")
    40  	if string(data) != "hello, world" || err != nil {
    41  		t.Fatalf(`ReadFile(readFileOnly, "hello.txt") = %q, %v, want %q, nil`, data, err, "hello, world")
    42  	}
    43  
    44  	// Test that ReadFile uses Open when the method is not present.
    45  	data, err = ReadFile(openOnly{testFsys}, "hello.txt")
    46  	if string(data) != "hello, world" || err != nil {
    47  		t.Fatalf(`ReadFile(openOnly, "hello.txt") = %q, %v, want %q, nil`, data, err, "hello, world")
    48  	}
    49  
    50  	// Test that ReadFile on Sub of . works (sub_test checks non-trivial subs).
    51  	sub, err := Sub(testFsys, ".")
    52  	if err != nil {
    53  		t.Fatal(err)
    54  	}
    55  	data, err = ReadFile(sub, "hello.txt")
    56  	if string(data) != "hello, world" || err != nil {
    57  		t.Fatalf(`ReadFile(sub(.), "hello.txt") = %q, %v, want %q, nil`, data, err, "hello, world")
    58  	}
    59  }