github.com/mvdan/u-root-coreutils@v0.0.0-20230122170626-c2eef2898555/pkg/uio/reader_test.go (about)

     1  // Copyright 2021 the u-root 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 uio
     6  
     7  import (
     8  	"os"
     9  	"path/filepath"
    10  	"strings"
    11  	"testing"
    12  )
    13  
    14  func readAndCheck(t *testing.T, want, tmpfileP string) {
    15  	t.Helper()
    16  	r := strings.NewReader(want)
    17  	if err := ReadIntoFile(r, tmpfileP); err != nil {
    18  		t.Errorf("ReadIntoFile(%v, %s) = %v, want no error", r, tmpfileP, err)
    19  	}
    20  
    21  	got, err := os.ReadFile(tmpfileP)
    22  	if err != nil {
    23  		t.Fatalf("os.ReadFile(%s) = %v, want no error", tmpfileP, err)
    24  	}
    25  	if want != string(got) {
    26  		t.Errorf("got: %v, want %s", string(got), want)
    27  	}
    28  }
    29  
    30  func TestReadIntoFile(t *testing.T) {
    31  	want := "I am the wanted"
    32  
    33  	dir := t.TempDir()
    34  
    35  	// Write to a file already exist.
    36  	p := filepath.Join(dir, "uio-out")
    37  	// Expect net effect to be creating a new empty file: "uio-out".
    38  	f, err := os.OpenFile(p, os.O_RDONLY|os.O_CREATE|os.O_TRUNC, 0o755)
    39  	if err != nil {
    40  		t.Fatal(err)
    41  	}
    42  	if err := f.Close(); err != nil {
    43  		t.Fatal(err)
    44  	}
    45  	readAndCheck(t, want, f.Name())
    46  
    47  	// Write to a file that does not exist.
    48  	p = filepath.Join(dir, "uio-out-not-existing")
    49  	readAndCheck(t, want, p)
    50  
    51  	// Write to an existing file that has pre-existing content.
    52  	p = filepath.Join(dir, "uio-out-prexist-content")
    53  	f, err = os.OpenFile(p, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0o755)
    54  	if err != nil {
    55  		t.Fatal(err)
    56  	}
    57  	if _, err := f.Write([]byte("temporary file's content")); err != nil {
    58  		t.Fatal(err)
    59  	}
    60  	if err := f.Close(); err != nil {
    61  		t.Fatal(err)
    62  	}
    63  	readAndCheck(t, want, p)
    64  }