cmd/gogio: extract endtoend driver base into a type

This type contains all the common bits, such as *testing.T, as well as
the channel and method used to wait for blocking until a frame is ready.

It also allows us to initialise this base separately from Start, which
keeps the exported method simpler to understand.

The base type is embedded into the specific driver types, so that the
code remains simple. While at it, start embedding *testing.T too, so
that we can write d.Fatalf instead of d.t.Fatalf. The drivers will only
have a small number of exported methods as per the interface, so it's
easy to keep those from colliding with the method set on T.

Signed-off-by: Daniel Martí <mvdan@mvdan.cc>

cmd/gogio/x11_test.go

@@ -16,22 +16,16 @@ import (
 	"os/exec"
 	"path/filepath"
 	"sync"
-	"testing"
 	"time"
 )
 
 type X11TestDriver struct {
-	t *testing.T
-
-	frameNotifs chan bool
+	driverBase
 
 	display string
 }
 
-func (d *X11TestDriver) Start(t_ *testing.T, path string, width, height int) {
-	d.frameNotifs = make(chan bool, 1)
-	d.t = t_
-
+func (d *X11TestDriver) Start(path string, width, height int) {
 	// Pick a random display number between 1 and 100,000. Most machines
 	// will only be using :0, so there's only a 0.001% chance of two
 	// concurrent test runs to run into a conflict.
@@ -57,16 +51,16 @@ func (d *X11TestDriver) Start(t_ *testing.T, path string, width, height int) {
 		"xdotool", // to send input
 	} {
 		if _, err := exec.LookPath(prog); err != nil {
-			d.t.Skipf("%s needed to run", prog)
+			d.Skipf("%s needed to run", prog)
 		}
 	}
 
 	// First, build the app.
 	dir, err := ioutil.TempDir("", "gio-endtoend-x11")
 	if err != nil {
-		d.t.Fatal(err)
+		d.Fatal(err)
 	}
-	d.t.Cleanup(func() { os.RemoveAll(dir) })
+	d.Cleanup(func() { os.RemoveAll(dir) })
 
 	bin := filepath.Join(dir, "red")
 	flags := []string{"build", "-tags", "nowayland", "-o=" + bin}
@@ -76,11 +70,11 @@ func (d *X11TestDriver) Start(t_ *testing.T, path string, width, height int) {
 	flags = append(flags, path)
 	cmd := exec.Command("go", flags...)
 	if out, err := cmd.CombinedOutput(); err != nil {
-		d.t.Fatalf("could not build app: %s:\n%s", err, out)
+		d.Fatalf("could not build app: %s:\n%s", err, out)
 	}
 
 	var wg sync.WaitGroup
-	d.t.Cleanup(wg.Wait)
+	d.Cleanup(wg.Wait)
 
 	// First, start the X server.
 	{
@@ -90,10 +84,10 @@ func (d *X11TestDriver) Start(t_ *testing.T, path string, width, height int) {
 		cmd.Stdout = combined
 		cmd.Stderr = combined
 		if err := cmd.Start(); err != nil {
-			d.t.Fatal(err)
+			d.Fatal(err)
 		}
-		d.t.Cleanup(cancel)
-		d.t.Cleanup(func() {
+		d.Cleanup(cancel)
+		d.Cleanup(func() {
 			// Give it a chance to exit gracefully, cleaning up
 			// after itself. After 10ms, the deferred cancel above
 			// will signal an os.Kill.
@@ -111,7 +105,7 @@ func (d *X11TestDriver) Start(t_ *testing.T, path string, width, height int) {
 				break
 			}
 			if i >= 100 {
-				d.t.Fatalf("timed out waiting for %s", socket)
+				d.Fatalf("timed out waiting for %s", socket)
 			}
 		}
 
@@ -120,7 +114,7 @@ func (d *X11TestDriver) Start(t_ *testing.T, path string, width, height int) {
 			if err := cmd.Wait(); err != nil && ctx.Err() == nil {
 				// Print all output and error.
 				io.Copy(os.Stdout, combined)
-				d.t.Error(err)
+				d.Error(err)
 			}
 			wg.Done()
 		}()
@@ -133,21 +127,21 @@ func (d *X11TestDriver) Start(t_ *testing.T, path string, width, height int) {
 		cmd.Env = []string{"DISPLAY=" + d.display}
 		stdout, err := cmd.StdoutPipe()
 		if err != nil {
-			d.t.Fatal(err)
+			d.Fatal(err)
 		}
 		stderr := &bytes.Buffer{}
 		cmd.Stderr = stderr
 
 		if err := cmd.Start(); err != nil {
-			d.t.Fatal(err)
+			d.Fatal(err)
 		}
-		d.t.Cleanup(cancel)
+		d.Cleanup(cancel)
 		wg.Add(1)
 		go func() {
 			if err := cmd.Wait(); err != nil && ctx.Err() == nil {
 				// Print stderr and error.
 				io.Copy(os.Stdout, stderr)
-				d.t.Error(err)
+				d.Error(err)
 			}
 			wg.Done()
 		}()
@@ -164,7 +158,7 @@ func (d *X11TestDriver) Start(t_ *testing.T, path string, width, height int) {
 	}
 
 	// Wait for the gio app to render.
-	waitForFrame(d.t, d.frameNotifs)
+	d.waitForFrame()
 }
 
 func (d *X11TestDriver) Screenshot() image.Image {
@@ -172,12 +166,12 @@ func (d *X11TestDriver) Screenshot() image.Image {
 	cmd.Env = []string{"DISPLAY=" + d.display}
 	out, err := cmd.CombinedOutput()
 	if err != nil {
-		d.t.Errorf("%s", out)
-		d.t.Fatal(err)
+		d.Errorf("%s", out)
+		d.Fatal(err)
 	}
 	img, err := png.Decode(bytes.NewReader(out))
 	if err != nil {
-		d.t.Fatal(err)
+		d.Fatal(err)
 	}
 	return img
 }
@@ -190,8 +184,8 @@ func (d *X11TestDriver) xdotool(args ...interface{}) {
 	cmd := exec.Command("xdotool", strs...)
 	cmd.Env = []string{"DISPLAY=" + d.display}
 	if out, err := cmd.CombinedOutput(); err != nil {
-		d.t.Errorf("%s", out)
-		d.t.Fatal(err)
+		d.Errorf("%s", out)
+		d.Fatal(err)
 	}
 }
 
@@ -200,5 +194,5 @@ func (d *X11TestDriver) Click(x, y int) {
 	d.xdotool("click", "1")
 
 	// Wait for the gio app to render after this click.
-	waitForFrame(d.t, d.frameNotifs)
+	d.waitForFrame()
 }