github.com/telepresenceio/telepresence/v2@v2.20.0-pro.6.0.20240517030216-236ea954e789/pkg/dos/filesystem_test.go (about)

     1  package dos_test
     2  
     3  import (
     4  	"context"
     5  	"errors"
     6  	"fmt"
     7  	"io"
     8  	"io/fs"
     9  	"log"
    10  	"os"
    11  	"path/filepath"
    12  	"testing"
    13  
    14  	"github.com/google/uuid"
    15  	"github.com/spf13/afero"
    16  	"github.com/stretchr/testify/assert"
    17  	"github.com/stretchr/testify/require"
    18  
    19  	"github.com/datawire/dlib/dlog"
    20  	"github.com/telepresenceio/telepresence/v2/pkg/dos"
    21  	"github.com/telepresenceio/telepresence/v2/pkg/dos/aferofs"
    22  )
    23  
    24  func TestWithFS(t *testing.T) {
    25  	appFS := afero.NewMemMapFs()
    26  	cData := []byte("file c\n")
    27  	dData := []byte("file d\n")
    28  	require.NoError(t, appFS.MkdirAll("a/b", 0o755))
    29  	require.NoError(t, afero.WriteFile(appFS, "/a/b/c.txt", cData, 0o644))
    30  	require.NoError(t, afero.WriteFile(appFS, "/a/d.txt", dData, 0o644))
    31  
    32  	ctx := dos.WithFS(dlog.NewTestContext(t, false), dos.WorkingDirWrapper(aferofs.Wrap(appFS)))
    33  
    34  	require.NoError(t, dos.Chdir(ctx, "/a/b"))
    35  	data, err := dos.ReadFile(ctx, "c.txt")
    36  	require.NoError(t, err)
    37  	require.Equal(t, cData, data)
    38  
    39  	require.NoError(t, dos.Chdir(ctx, "../.."))
    40  	f, err := dos.Open(ctx, "/a/d.txt")
    41  	require.NoError(t, err)
    42  	data, err = io.ReadAll(f)
    43  	require.NoError(t, err)
    44  	require.NoError(t, f.Close())
    45  	require.Equal(t, dData, data)
    46  }
    47  
    48  func TestFileNil(t *testing.T) {
    49  	// This function will return a File interface that points to a nil *os.File. That's
    50  	// not the same as a File interface which is nil.
    51  	neverDoThis := func(name string) (dos.File, error) {
    52  		return os.Open(name)
    53  	}
    54  
    55  	dlog.NewTestContext(t, false)
    56  	uuid, err := uuid.NewUUID()
    57  	badFile := filepath.Join(fmt.Sprintf("%c%s", filepath.Separator, uuid), "does", "not", "exist")
    58  	require.NoError(t, err)
    59  	f, err := neverDoThis(badFile)
    60  	assert.Error(t, err)
    61  	assert.True(t, f != nil) // Do NOT change this to assert.NotNil(t, f) because that test is flawed.
    62  	assert.Nil(t, f)         // Told you so. It is flawed!
    63  
    64  	f, err = dos.Open(context.Background(), badFile)
    65  	assert.Error(t, err)
    66  	assert.True(t, f == nil) // Do NOT change this to assert.Nil(t, f) because that test is flawed.
    67  	f, err = dos.OpenFile(context.Background(), badFile, os.O_RDONLY, 0o600)
    68  	assert.Error(t, err)
    69  	assert.True(t, f == nil) // Do NOT change this to assert.Nil(t, f) because that test is flawed.
    70  	f, err = dos.Create(context.Background(), badFile)
    71  	assert.Error(t, err)
    72  	assert.True(t, f == nil) // Do NOT change this to assert.Nil(t, f) because that test is flawed.
    73  }
    74  
    75  // Example using afero.MemMapFs.
    76  func ExampleWithFS() {
    77  	appFS := afero.NewCopyOnWriteFs(afero.NewOsFs(), afero.NewMemMapFs())
    78  	ctx := dos.WithFS(context.Background(), aferofs.Wrap(appFS))
    79  
    80  	if err := dos.MkdirAll(ctx, "/etc", 0o700); err != nil {
    81  		log.Fatal(err)
    82  	}
    83  	hosts, err := dos.Create(ctx, "/etc/example.conf")
    84  	if err != nil {
    85  		log.Fatal(err)
    86  	}
    87  	fmt.Fprintln(hosts, "example = conf")
    88  	hosts.Close()
    89  
    90  	if hosts, err = dos.Open(ctx, "/etc/example.conf"); err != nil {
    91  		log.Fatal(err)
    92  	}
    93  	_, err = io.Copy(os.Stdout, hosts)
    94  	_ = hosts.Close()
    95  	if err != nil {
    96  		log.Fatal(err)
    97  	}
    98  
    99  	if hosts, err = dos.Open(context.Background(), "/etc/example.conf"); err != nil {
   100  		if errors.Is(err, fs.ErrNotExist) {
   101  			fmt.Println("file does not exist")
   102  		} else {
   103  			fmt.Println(err)
   104  		}
   105  	}
   106  	// Output:
   107  	// example = conf
   108  	// file does not exist
   109  }