daemon/logger: test followLogs' handleDecodeErr case

Kazuyoshi Kato · Kazuyoshi Kato · commit 3cf392953a6d · 2021-12-09T13:27:22.000-08:00
Signed-off-by: Kazuyoshi Kato &lt;katokazu@amazon.com&gt;
diff --git a/daemon/logger/loggerutils/logfile_test.go b/daemon/logger/loggerutils/logfile_test.go
@@ -4,11 +4,13 @@ import (
 	"bufio"
 	"bytes"
 	"context"
+	"errors"
 	"fmt"
 	"io"
 	"os"
 	"path/filepath"
 	"strings"
+	"sync"
 	"sync/atomic"
 	"testing"
 	"text/tabwriter"
@@ -244,6 +246,77 @@ func TestFollowLogsProducerGone(t *testing.T) {
 	}
 }
 
+type lineDecoder struct {
+	r          *bufio.Reader
+	resetCount int
+}
+
+func (d *lineDecoder) Decode() (*logger.Message, error) {
+	line, err := d.r.ReadString('\n')
+	if err != nil {
+		return nil, err
+	}
+	m := logger.NewMessage()
+	m.Line = []byte(line)
+	return m, nil
+}
+
+func (d *lineDecoder) Reset(r io.Reader) {
+	d.r = bufio.NewReader(r)
+	d.resetCount++
+}
+
+func (d *lineDecoder) Close() {
+}
+
+func TestFollowLogsHandleDecodeErr(t *testing.T) {
+	lw := logger.NewLogWatcher()
+	defer lw.ConsumerGone()
+
+	fw, err := os.CreateTemp("", t.Name())
+	assert.NilError(t, err)
+	defer os.Remove(fw.Name())
+
+	fr, err := os.Open(fw.Name())
+	assert.NilError(t, err)
+
+	dec := &lineDecoder{}
+	dec.Reset(fr)
+
+	var since, until time.Time
+	rotate := make(chan interface{})
+	evict := make(chan interface{})
+
+	var wg sync.WaitGroup
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+		followLogs(fr, lw, rotate, evict, dec, since, until)
+	}()
+
+	sendReceive := func(f io.Writer, message string) {
+		_, err = f.Write([]byte(message))
+		assert.NilError(t, err)
+		m := <-lw.Msg
+		assert.Equal(t, message, string(m.Line))
+	}
+
+	sendReceive(fw, "log1\n")
+	sendReceive(fw, "log2\n")
+
+	ft, err := os.OpenFile(fw.Name(), os.O_WRONLY|os.O_TRUNC, 0600)
+	assert.NilError(t, err)
+
+	sendReceive(ft, "log3\n")
+
+	evict <- errors.New("stop followLogs")
+	wg.Wait()
+
+	// followLogs calls Reset() in the beginning,
+	// each 3 writes result Reset(), then handleDecodeErr() calles Reset().
+	assert.Equal(t, 5, dec.resetCount)
+}
+
 func TestCheckCapacityAndRotate(t *testing.T) {
 	dir, err := os.MkdirTemp("", t.Name())
 	assert.NilError(t, err)
