[#61844] linux-client: download: Add unit tests

devices/linux-client/download/cached_fetcher_test.go

@@ -0,0 +1,72 @@
+package download
+
+import (
+	"bytes"
+	"github.com/stretchr/testify/assert"
+	"io"
+	"testing"
+)
+
+var FirstTestData = []byte{0x60, 0x09, 0x20, 0x01, 0x30, 0x07}
+var SecondTestData = []byte{0x04, 0x00, 0x02, 0x66}
+
+type BufferCloser struct {
+	*bytes.Buffer
+}
+
+func (b *BufferCloser) Close() error { return nil }
+
+func TestReadSaver(t *testing.T) {
+	readSaver := &ReadSaver{offset: 0}
+	readSaver.Write(FirstTestData)
+
+	readBackBuffer, err := readNBytes(readSaver, len(FirstTestData))
+
+	assert.NoError(t, err)
+	assert.Equal(t, FirstTestData, readBackBuffer)
+}
+
+func TestCombinedSourceReader(t *testing.T) {
+	firstDataReader := &BufferCloser{bytes.NewBuffer(FirstTestData)}
+	secondDataReader := &BufferCloser{bytes.NewBuffer(SecondTestData)}
+
+	combinedSourceReader := &CombinedSourceReader{
+		firstReader:    firstDataReader,
+		firstReaderEOF: false,
+		secondReader:   secondDataReader,
+	}
+
+	readBackBuffer, err := readNBytes(combinedSourceReader, len(FirstTestData)+len(SecondTestData))
+
+	assert.NoError(t, err)
+	assert.Equal(t, append(FirstTestData, SecondTestData...), readBackBuffer)
+}
+
+func TestTeeReadCloser(t *testing.T) {
+	readBackBuffer := bytes.NewBuffer([]byte{})
+	firstDataReader := &BufferCloser{bytes.NewBuffer(FirstTestData)}
+	dataWriter := &BufferCloser{readBackBuffer}
+
+	teeReadCloser := &TeeReadCloser{
+		reader: firstDataReader,
+		writer: dataWriter,
+	}
+
+	_, err := readNBytes(teeReadCloser, len(FirstTestData))
+	assert.NoError(t, err)
+	assert.Equal(t, FirstTestData, readBackBuffer.Bytes())
+}
+
+func readNBytes(reader io.Reader, length int) ([]byte, error) {
+	var err error
+	readBackBuffer := make([]byte, length)
+	bytesRead := 0
+	for {
+		n, err := reader.Read(readBackBuffer[bytesRead:])
+		bytesRead += n
+		if bytesRead >= length || err != nil {
+			break
+		}
+	}
+	return readBackBuffer, err
+}