From 56b8c594e58c16363cf78ac04c5f2344517b466c Mon Sep 17 00:00:00 2001
From: Philip Potter <phil@replicate.com>
Date: Thu, 7 Mar 2024 13:23:58 +0000
Subject: [PATCH] test bufferedReader

---
 pkg/download/buffered_reader_test.go | 84 ++++++++++++++++++++++++++++
 1 file changed, 84 insertions(+)
 create mode 100644 pkg/download/buffered_reader_test.go

diff --git a/pkg/download/buffered_reader_test.go b/pkg/download/buffered_reader_test.go
new file mode 100644
index 0000000..f28a6a0
--- /dev/null
+++ b/pkg/download/buffered_reader_test.go
@@ -0,0 +1,84 @@
+package download
+
+import (
+	"bytes"
+	"io"
+	"strings"
+	"sync"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestBufferedReaderSerial(t *testing.T) {
+	pool := newBufferPool(10)
+	br := newBufferedReader(pool)
+	n, err := br.ReadFrom(strings.NewReader("foobar"))
+	assert.NoError(t, err)
+	assert.Equal(t, int64(6), n)
+	br.Done()
+	buf, err := io.ReadAll(br)
+	assert.NoError(t, err)
+	assert.Equal(t, "foobar", string(buf))
+}
+
+func TestBufferedReaderParallel(t *testing.T) {
+	pool := newBufferPool(10)
+	br := newBufferedReader(pool)
+	wg := new(sync.WaitGroup)
+	wg.Add(1)
+	go func() {
+		defer br.Done()
+		defer wg.Done()
+		n, err := br.ReadFrom(strings.NewReader("foobar"))
+		assert.NoError(t, err)
+		assert.Equal(t, int64(6), n)
+	}()
+	buf, err := io.ReadAll(br)
+	assert.NoError(t, err)
+	assert.Equal(t, "foobar", string(buf))
+	wg.Wait()
+}
+
+func TestBufferedReaderReadsWholeChunk(t *testing.T) {
+	chunkSize := int64(1024 * 1024)
+	pool := newBufferPool(chunkSize)
+	br := newBufferedReader(pool)
+	data := bytes.Repeat([]byte("x"), int(chunkSize))
+	n64, err := br.ReadFrom(bytes.NewReader(data))
+	assert.NoError(t, err)
+	assert.Equal(t, chunkSize, n64)
+	br.Done()
+	buf := make([]byte, chunkSize)
+	// We should only require a single Read() call because all the data should
+	// be buffered
+	n, err := br.Read(buf)
+	assert.NoError(t, err)
+	assert.Equal(t, data, buf)
+	assert.Equal(t, int(chunkSize), n)
+}
+
+func TestBufferedReaderSubsequentReadsReturnEOF(t *testing.T) {
+	pool := newBufferPool(10)
+	br := newBufferedReader(pool)
+	n64, err := br.ReadFrom(strings.NewReader("foobar"))
+	assert.NoError(t, err)
+	assert.Equal(t, int64(6), n64)
+	br.Done()
+	buf, err := io.ReadAll(br)
+	assert.NoError(t, err)
+	assert.Equal(t, "foobar", string(buf))
+
+	n, err := br.Read(buf)
+	assert.Equal(t, 0, n)
+	assert.ErrorIs(t, err, io.EOF)
+}
+
+func TestBufferedReaderDoneWithoutReadFrom(t *testing.T) {
+	pool := newBufferPool(10)
+	br := newBufferedReader(pool)
+	br.Done()
+	buf, err := io.ReadAll(br)
+	assert.NoError(t, err)
+	assert.Equal(t, 0, len(buf))
+}