Improve test logger (#24235)

Before, there was a `log/buffer.go`, but that design is not general, and
it introduces a lot of irrelevant `Content() (string, error) ` and
`return "", fmt.Errorf("not supported")` .


And the old `log/buffer.go` is difficult to use, developers have to
write a lot of `Contains` and `Sleep` code.


The new `LogChecker` is designed to be a general approach to help to
assert some messages appearing or not appearing in logs.

2 files changed, 163 insertions, 0 deletions

diff --git a/modules/test/logchecker.go b/modules/test/logchecker.go
new file mode 100644
index 0000000000..8f8c753c76
--- /dev/null
+++ b/modules/test/logchecker.go
@@ -0,0 +1,116 @@
+// Copyright 2023 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package test
+
+import (
+	"strconv"
+	"strings"
+	"sync"
+	"sync/atomic"
+	"time"
+
+	"code.gitea.io/gitea/modules/log"
+)
+
+type LogChecker struct {
+	logger          *log.MultiChannelledLogger
+	loggerName      string
+	eventLoggerName string
+
+	filterMessages []string
+	filtered       []bool
+
+	stopMark string
+	stopped  bool
+
+	mu sync.Mutex
+}
+
+func (lc *LogChecker) LogEvent(event *log.Event) error {
+	lc.mu.Lock()
+	defer lc.mu.Unlock()
+	for i, msg := range lc.filterMessages {
+		if strings.Contains(event.GetMsg(), msg) {
+			lc.filtered[i] = true
+		}
+	}
+	if strings.Contains(event.GetMsg(), lc.stopMark) {
+		lc.stopped = true
+	}
+	return nil
+}
+
+func (lc *LogChecker) Close() {}
+
+func (lc *LogChecker) Flush() {}
+
+func (lc *LogChecker) GetLevel() log.Level {
+	return log.TRACE
+}
+
+func (lc *LogChecker) GetStacktraceLevel() log.Level {
+	return log.NONE
+}
+
+func (lc *LogChecker) GetName() string {
+	return lc.eventLoggerName
+}
+
+func (lc *LogChecker) ReleaseReopen() error {
+	return nil
+}
+
+var checkerIndex int64
+
+func NewLogChecker(loggerName string) (logChecker *LogChecker, cancel func()) {
+	logger := log.GetLogger(loggerName)
+	newCheckerIndex := atomic.AddInt64(&checkerIndex, 1)
+	lc := &LogChecker{
+		logger:          logger,
+		loggerName:      loggerName,
+		eventLoggerName: "TestLogChecker-" + strconv.FormatInt(newCheckerIndex, 10),
+	}
+	if err := logger.AddLogger(lc); err != nil {
+		panic(err) // it's impossible
+	}
+	return lc, func() { _, _ = logger.DelLogger(lc.GetName()) }
+}
+
+// Filter will make the `Check` function to check if these logs are outputted.
+func (lc *LogChecker) Filter(msgs ...string) *LogChecker {
+	lc.mu.Lock()
+	defer lc.mu.Unlock()
+	lc.filterMessages = make([]string, len(msgs))
+	copy(lc.filterMessages, msgs)
+	lc.filtered = make([]bool, len(lc.filterMessages))
+	return lc
+}
+
+func (lc *LogChecker) StopMark(msg string) *LogChecker {
+	lc.mu.Lock()
+	defer lc.mu.Unlock()
+	lc.stopMark = msg
+	lc.stopped = false
+	return lc
+}
+
+// Check returns the filtered slice and whether the stop mark is reached.
+func (lc *LogChecker) Check(d time.Duration) (filtered []bool, stopped bool) {
+	stop := time.Now().Add(d)
+
+	for {
+		lc.mu.Lock()
+		stopped = lc.stopped
+		lc.mu.Unlock()
+
+		if time.Now().After(stop) || stopped {
+			lc.mu.Lock()
+			f := make([]bool, len(lc.filtered))
+			copy(f, lc.filtered)
+			lc.mu.Unlock()
+			return f, stopped
+		}
+		time.Sleep(10 * time.Millisecond)
+	}
+}
diff --git a/modules/test/logchecker_test.go b/modules/test/logchecker_test.go
new file mode 100644
index 0000000000..1ed7f427f4
--- /dev/null
+++ b/modules/test/logchecker_test.go
@@ -0,0 +1,47 @@
+// Copyright 2023 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package test
+
+import (
+	"testing"
+	"time"
+
+	"code.gitea.io/gitea/modules/log"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestLogChecker(t *testing.T) {
+	_ = log.NewLogger(1000, "console", "console", `{"level":"info","stacktracelevel":"NONE","stderr":true}`)
+
+	lc, cleanup := NewLogChecker(log.DEFAULT)
+	defer cleanup()
+
+	lc.Filter("First", "Third").StopMark("End")
+	log.Info("test")
+
+	filtered, stopped := lc.Check(100 * time.Millisecond)
+	assert.EqualValues(t, []bool{false, false}, filtered)
+	assert.EqualValues(t, false, stopped)
+
+	log.Info("First")
+	filtered, stopped = lc.Check(100 * time.Millisecond)
+	assert.EqualValues(t, []bool{true, false}, filtered)
+	assert.EqualValues(t, false, stopped)
+
+	log.Info("Second")
+	filtered, stopped = lc.Check(100 * time.Millisecond)
+	assert.EqualValues(t, []bool{true, false}, filtered)
+	assert.EqualValues(t, false, stopped)
+
+	log.Info("Third")
+	filtered, stopped = lc.Check(100 * time.Millisecond)
+	assert.EqualValues(t, []bool{true, true}, filtered)
+	assert.EqualValues(t, false, stopped)
+
+	log.Info("End")
+	filtered, stopped = lc.Check(100 * time.Millisecond)
+	assert.EqualValues(t, []bool{true, true}, filtered)
+	assert.EqualValues(t, true, stopped)
+}