test: Use flock to make tests exclusive

Fixes #575

image_test.go

@@ -29,9 +29,13 @@ import (
 	"github.com/hajimehoshi/ebiten/ebitenutil"
 	"github.com/hajimehoshi/ebiten/examples/resources/images"
 	emath "github.com/hajimehoshi/ebiten/internal/math"
+	"github.com/hajimehoshi/ebiten/internal/testflock"
 )
 
 func TestMain(m *testing.M) {
+	testflock.Lock()
+	defer testflock.Unlock()
+
 	code := 0
 	// Run an Ebiten process so that (*Image).At is available.
 	regularTermination := errors.New("regular termination")

internal/restorable/images_test.go

@@ -26,9 +26,13 @@ import (
 	"github.com/hajimehoshi/ebiten/internal/graphics"
 	"github.com/hajimehoshi/ebiten/internal/opengl"
 	. "github.com/hajimehoshi/ebiten/internal/restorable"
+	"github.com/hajimehoshi/ebiten/internal/testflock"
 )
 
 func TestMain(m *testing.M) {
+	testflock.Lock()
+	defer testflock.Unlock()
+
 	EnableRestoringForTesting()
 	code := 0
 	regularTermination := errors.New("regular termination")

internal/shareable/shareable_test.go

@@ -25,9 +25,13 @@ import (
 	"github.com/hajimehoshi/ebiten/internal/graphics"
 	"github.com/hajimehoshi/ebiten/internal/opengl"
 	. "github.com/hajimehoshi/ebiten/internal/shareable"
+	"github.com/hajimehoshi/ebiten/internal/testflock"
 )
 
 func TestMain(m *testing.M) {
+	testflock.Lock()
+	defer testflock.Unlock()
+
 	code := 0
 	regularTermination := errors.New("regular termination")
 	f := func(screen *ebiten.Image) error {
@@ -42,8 +46,7 @@ func TestMain(m *testing.M) {
 
 const bigSize = 2049
 
-// Temporary disabled per #575.
-func Disabled_TestEnsureNotShared(t *testing.T) {
+func TestEnsureNotShared(t *testing.T) {
 	// Create img1 and img2 with this size so that the next images are allocated
 	// with non-upper-left location.
 	img1 := NewImage(bigSize, 100)

internal/testflock/flock.go

@@ -0,0 +1,41 @@
+// Copyright 2018 The Ebiten 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 testflock provides a lock for testing.
+//
+// There is a CI service like TravisCI where multiple OpenGL processes
+// don't work well at the same time, and tests with an OpenGL main routine
+// should be protected by a file lock (#575).
+package testflock
+
+import (
+	"os"
+	"path/filepath"
+
+	"github.com/theckman/go-flock"
+)
+
+var theLock = flock.NewFlock(filepath.Join(os.TempDir(), "ebitentest"))
+
+func Lock() {
+	if err := theLock.Lock(); err != nil {
+		panic(err)
+	}
+}
+
+func Unlock() {
+	if err := theLock.Unlock(); err != nil {
+		panic(err)
+	}
+}

text/text_test.go

@@ -21,12 +21,15 @@ import (
 	"testing"
 
 	"github.com/hajimehoshi/ebiten"
-	"github.com/hajimehoshi/go-mplusbitmap"
-
+	"github.com/hajimehoshi/ebiten/internal/testflock"
 	. "github.com/hajimehoshi/ebiten/text"
+	"github.com/hajimehoshi/go-mplusbitmap"
 )
 
 func TestMain(m *testing.M) {
+	testflock.Lock()
+	defer testflock.Unlock()
+
 	code := 0
 	// Run an Ebiten process so that (*Image).At is available.
 	regularTermination := errors.New("regular termination")