Added rclone archive command to create and read archive files

Co-Authored-By: Nick Craig-Wood <nick@craig-wood.com>

cmd/archive/files/countwriter_test.go

@@ -0,0 +1,109 @@
+package files
+
+import (
+	"errors"
+	"io"
+	"sync"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+type stubWriter struct {
+	n   int
+	err error
+}
+
+func (s stubWriter) Write(p []byte) (int, error) {
+	if s.n > len(p) {
+		return len(p), s.err
+	}
+	return s.n, s.err
+}
+
+func TestCountWriter(t *testing.T) {
+	t.Parallel()
+
+	t.Run("initial count is zero", func(t *testing.T) {
+		cw := NewCountWriter(io.Discard)
+		require.Equal(t, uint64(0), cw.Count())
+	})
+
+	t.Run("counts bytes with real writes", func(t *testing.T) {
+		cw := NewCountWriter(io.Discard)
+		n, err := cw.Write([]byte("abcd"))
+		require.NoError(t, err)
+		require.Equal(t, 4, n)
+		assert.Equal(t, uint64(4), cw.Count())
+
+		n, err = cw.Write([]byte("xyz"))
+		require.NoError(t, err)
+		require.Equal(t, 3, n)
+		assert.Equal(t, uint64(7), cw.Count())
+	})
+
+	t.Run("nil writer uses io.Discard", func(t *testing.T) {
+		cw := NewCountWriter(nil)
+		n, err := cw.Write([]byte("ok"))
+		require.NoError(t, err)
+		require.Equal(t, 2, n)
+		assert.Equal(t, uint64(2), cw.Count())
+	})
+
+	t.Run("zero-length write does not change count", func(t *testing.T) {
+		cw := NewCountWriter(io.Discard)
+		n, err := cw.Write(nil)
+		require.NoError(t, err)
+		require.Equal(t, 0, n)
+		assert.Equal(t, uint64(0), cw.Count())
+	})
+
+	t.Run("partial write with error counts n and returns error", func(t *testing.T) {
+		s := stubWriter{n: 3, err: errors.New("boom")}
+		cw := NewCountWriter(s)
+		n, err := cw.Write([]byte("abcdef"))
+		require.Error(t, err)
+		require.Equal(t, 3, n)
+		assert.Equal(t, uint64(3), cw.Count())
+	})
+
+	t.Run("short successful write counts returned n", func(t *testing.T) {
+		s := stubWriter{n: 1}
+		cw := NewCountWriter(s)
+		n, err := cw.Write([]byte("hi"))
+		require.NoError(t, err)
+		require.Equal(t, 1, n)
+		assert.Equal(t, uint64(1), cw.Count())
+	})
+}
+
+func TestCountWriterConcurrent(t *testing.T) {
+	t.Parallel()
+
+	const (
+		goroutines = 32
+		loops      = 200
+		chunkSize  = 64
+	)
+	data := make([]byte, chunkSize)
+
+	cw := NewCountWriter(io.Discard)
+
+	var wg sync.WaitGroup
+	wg.Add(goroutines)
+	for g := 0; g < goroutines; g++ {
+		go func() {
+			defer wg.Done()
+			for i := 0; i < loops; i++ {
+				n, err := cw.Write(data)
+				assert.NoError(t, err)
+				assert.Equal(t, chunkSize, n)
+			}
+		}()
+	}
+	wg.Wait()
+
+	want := uint64(goroutines * loops * chunkSize)
+	assert.Equal(t, want, cw.Count())
+}