suspendible ticker unit testing

Signed-off-by: Shlomi Noach <[email protected]>

go/timer/suspendable_ticker_test.go

@@ -0,0 +1,140 @@
+/*
+Copyright 2020 The Vitess Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package timer
+
+import (
+	"context"
+	"sync/atomic"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestInitiallySuspended(t *testing.T) {
+	ctx := context.Background()
+	t.Run("true", func(t *testing.T) {
+		ctx, cancel := context.WithTimeout(ctx, time.Second)
+		defer cancel()
+		ticker := NewSuspendableTicker(10*time.Millisecond, true)
+		defer ticker.Stop()
+		select {
+		case <-ticker.C:
+			assert.Fail(t, "unexpected tick. Was supposed to be suspended")
+		case <-ctx.Done():
+			return
+		}
+	})
+	t.Run("false", func(t *testing.T) {
+		ctx, cancel := context.WithTimeout(ctx, time.Second)
+		defer cancel()
+		ticker := NewSuspendableTicker(10*time.Millisecond, false)
+		defer ticker.Stop()
+		select {
+		case <-ticker.C:
+			return
+		case <-ctx.Done():
+			assert.Fail(t, "unexpected timeout. Expected tick")
+		}
+	})
+}
+
+func TestSuspendableTicker(t *testing.T) {
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+	ticker := NewSuspendableTicker(10*time.Millisecond, false)
+	defer ticker.Stop()
+
+	var ticks atomic.Int64
+	go func() {
+		for {
+			select {
+			case <-ctx.Done():
+				return
+			case <-ticker.C:
+				ticks.Add(1)
+			}
+		}
+	}()
+	t.Run("ticks running", func(t *testing.T) {
+		time.Sleep(time.Second)
+		after := ticks.Load()
+		assert.Greater(t, after, int64(10)) // should be about 100
+	})
+	t.Run("ticks suspended", func(t *testing.T) {
+		ticker.Suspend()
+		before := ticks.Load()
+		time.Sleep(time.Second)
+		after := ticks.Load()
+		assert.Less(t, after-before, int64(10))
+	})
+	t.Run("ticks resumed", func(t *testing.T) {
+		ticker.Resume()
+		before := ticks.Load()
+		time.Sleep(time.Second)
+		after := ticks.Load()
+		assert.Greater(t, after-before, int64(10))
+	})
+	t.Run("ticker stopped", func(t *testing.T) {
+		ticker.Stop()
+		before := ticks.Load()
+		time.Sleep(time.Second)
+		after := ticks.Load()
+		assert.Less(t, after-before, int64(10))
+	})
+}
+
+func TestSuspendableTickerTick(t *testing.T) {
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+	ticker := NewSuspendableTicker(time.Hour, false)
+	defer ticker.Stop()
+
+	var ticks atomic.Int64
+	go func() {
+		for {
+			select {
+			case <-ctx.Done():
+				return
+			case <-ticker.C:
+				ticks.Add(1)
+			}
+		}
+	}()
+	t.Run("nothing going on", func(t *testing.T) {
+		time.Sleep(time.Second)
+		after := ticks.Load()
+		assert.Zero(t, after)
+	})
+	t.Run("tick now", func(t *testing.T) {
+		before := ticks.Load()
+		ticker.TickNow()
+		time.Sleep(time.Second)
+		after := ticks.Load()
+		assert.Equal(t, int64(1), after-before)
+	})
+	t.Run("tick after", func(t *testing.T) {
+		before := ticks.Load()
+		ticker.TickAfter(1 * time.Second)
+		time.Sleep(time.Second)
+		after := ticks.Load()
+		assert.Zero(t, after-before)
+		time.Sleep(3 * time.Second)
+		after = ticks.Load()
+		assert.Equal(t, int64(1), after-before)
+	})
+}