Merge pull request #29282 from ROKUMATE/test-pkg-channel

pkg/channel: add tests for the channel WriteCloser

pkg/channel/writer_test.go

@@ -0,0 +1,82 @@
+package channel
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestNewWriterWriteQueuesMessage(t *testing.T) {
+	ch := make(chan []byte, 1)
+	w := NewWriter(ch)
+
+	n, err := w.Write([]byte("hello"))
+	require.NoError(t, err)
+	assert.Equal(t, 5, n)
+	assert.Equal(t, []byte("hello"), <-ch)
+}
+
+func TestWriterChanReturnsUnderlyingChannel(t *testing.T) {
+	ch := make(chan []byte, 1)
+	w := NewWriter(ch)
+
+	_, err := w.Write([]byte("data"))
+	require.NoError(t, err)
+	assert.Equal(t, []byte("data"), <-w.Chan())
+}
+
+func TestWriterWriteCopiesInput(t *testing.T) {
+	ch := make(chan []byte, 1)
+	w := NewWriter(ch)
+
+	input := []byte("abc")
+	_, err := w.Write(input)
+	require.NoError(t, err)
+
+	// Mutating the caller's buffer after Write must not affect the queued message.
+	input[0] = 'x'
+	assert.Equal(t, []byte("abc"), <-ch)
+}
+
+func TestWriterPreservesMessageOrder(t *testing.T) {
+	ch := make(chan []byte, 3)
+	w := NewWriter(ch)
+
+	for _, msg := range []string{"one", "two", "three"} {
+		_, err := w.Write([]byte(msg))
+		require.NoError(t, err)
+	}
+	assert.Equal(t, []byte("one"), <-ch)
+	assert.Equal(t, []byte("two"), <-ch)
+	assert.Equal(t, []byte("three"), <-ch)
+}
+
+func TestWriterCloseClosesChannel(t *testing.T) {
+	ch := make(chan []byte, 1)
+	w := NewWriter(ch)
+
+	require.NoError(t, w.Close())
+
+	_, ok := <-ch
+	assert.False(t, ok, "channel should be closed after Close")
+}
+
+func TestWriterWriteAfterCloseFails(t *testing.T) {
+	ch := make(chan []byte, 1)
+	w := NewWriter(ch)
+	require.NoError(t, w.Close())
+
+	n, err := w.Write([]byte("data"))
+	assert.Equal(t, 0, n)
+	require.Error(t, err)
+	assert.Contains(t, err.Error(), "channel is closed for Write")
+}
+
+func TestWriterWriteNilReceiverFails(t *testing.T) {
+	var w *writeCloser
+	n, err := w.Write([]byte("data"))
+	assert.Equal(t, 0, n)
+	require.Error(t, err)
+	assert.Contains(t, err.Error(), "channel.NewWriter()")
+}