Add a test for compression

Signed-off-by: Chris Marchbanks <[email protected]>

Author: csmarchbanks

testutil/directory.go

@@ -16,6 +16,7 @@ package testutil
 import (
 	"io/ioutil"
 	"os"
+	"path/filepath"
 )
 
 const (
@@ -127,3 +128,18 @@ func NewTemporaryDirectory(name string, t T) (handler TemporaryDirectory) {
 
 	return
 }
+
+// DirSize returns the size in bytes of all files in a directory.
+func DirSize(path string) (int64, error) {
+	var size int64
+	err := filepath.Walk(path, func(_ string, info os.FileInfo, err error) error {
+		if err != nil {
+			return err
+		}
+		if !info.IsDir() {
+			size += info.Size()
+		}
+		return nil
+	})
+	return size, err
+}

wal/wal_test.go

@@ -370,6 +370,46 @@ func TestSegmentMetric(t *testing.T) {
 	testutil.Ok(t, w.Close())
 }
 
+func TestCompression(t *testing.T) {
+	boostrap := func(compressed bool) string {
+		const (
+			segmentSize = pageSize
+			recordSize  = (pageSize / 2) - recordHeaderSize
+			records     = 100
+		)
+
+		dirPath, err := ioutil.TempDir("", fmt.Sprintf("TestCompression_%t", compressed))
+		testutil.Ok(t, err)
+
+		w, err := NewSize(nil, nil, dirPath, segmentSize, compressed)
+		testutil.Ok(t, err)
+
+		buf := make([]byte, recordSize)
+		for i := 0; i < records; i++ {
+			testutil.Ok(t, w.Log(buf))
+		}
+		testutil.Ok(t, w.Close())
+
+		return dirPath
+	}
+
+	dirCompressed := boostrap(true)
+	defer func() {
+		testutil.Ok(t, os.RemoveAll(dirCompressed))
+	}()
+	dirUnCompressed := boostrap(false)
+	defer func() {
+		testutil.Ok(t, os.RemoveAll(dirUnCompressed))
+	}()
+
+	uncompressedSize, err := testutil.DirSize(dirUnCompressed)
+	testutil.Ok(t, err)
+	compressedSize, err := testutil.DirSize(dirCompressed)
+	testutil.Ok(t, err)
+
+	testutil.Assert(t, float64(uncompressedSize)*0.75 > float64(compressedSize), "Compressing zeroes should save at least 25%% space - uncompressedSize: %d, compressedSize: %d", uncompressedSize, compressedSize)
+}
+
 func BenchmarkWAL_LogBatched(b *testing.B) {
 	for _, compress := range []bool{true, false} {
 		b.Run(fmt.Sprintf("compress=%t", compress), func(b *testing.B) {