Update loopback to return error

Avoid calling testing function in creation closure since the
context may no longer be valid.

Signed-off-by: Derek McGowan <derek@mcgstyle.net>

fs/dtype_linux_test.go

@@ -20,7 +20,10 @@ func testSupportsDType(t *testing.T, expected bool, mkfs ...string) {
 	}
 	defer os.RemoveAll(mnt)
 
-	deviceName, cleanupDevice := testutil.NewLoopback(t, 100<<20) // 100 MB
+	deviceName, cleanupDevice, err := testutil.NewLoopback(100 << 20) // 100 MB
+	if err != nil {
+		t.Fatal(err)
+	}
 	if out, err := exec.Command(mkfs[0], append(mkfs[1:], deviceName)...).CombinedOutput(); err != nil {
 		// not fatal
 		t.Skipf("could not mkfs (%v) %s: %v (out: %q)", mkfs, deviceName, err, string(out))

mount/lookup_test/lookup_linux_test.go

@@ -29,7 +29,10 @@ func testLookup(t *testing.T, fsType string) {
 	}
 	defer os.RemoveAll(mnt)
 
-	deviceName, cleanupDevice := testutil.NewLoopback(t, 100<<20) // 100 MB
+	deviceName, cleanupDevice, err := testutil.NewLoopback(100 << 20) // 100 MB
+	if err != nil {
+		t.Fatal(err)
+	}
 	if out, err := exec.Command("mkfs", "-t", fsType, deviceName).CombinedOutput(); err != nil {
 		// not fatal
 		t.Skipf("could not mkfs (%s) %s: %v (out: %q)", fsType, deviceName, err, string(out))

snapshot/btrfs/btrfs_test.go

@@ -15,30 +15,41 @@ import (
 	"github.com/containerd/containerd/snapshot"
 	"github.com/containerd/containerd/snapshot/testsuite"
 	"github.com/containerd/containerd/testutil"
+	"github.com/pkg/errors"
 )
 
 func boltSnapshotter(t *testing.T) func(context.Context, string) (snapshot.Snapshotter, func(), error) {
+	mkbtrfs, err := exec.LookPath("mkfs.btrfs")
+	if err != nil {
+		t.Skipf("could not find mkfs.btrfs: %v", err)
+	}
+
+	// TODO: Check for btrfs in /proc/module and skip if not loaded
+
 	return func(ctx context.Context, root string) (snapshot.Snapshotter, func(), error) {
 
-		deviceName, cleanupDevice := testutil.NewLoopback(t, 100<<20) // 100 MB
+		deviceName, cleanupDevice, err := testutil.NewLoopback(100 << 20) // 100 MB
+		if err != nil {
+			return nil, nil, err
+		}
 
-		if out, err := exec.Command("mkfs.btrfs", deviceName).CombinedOutput(); err != nil {
+		if out, err := exec.Command(mkbtrfs, deviceName).CombinedOutput(); err != nil {
-			// not fatal
+			return nil, nil, errors.Wrapf(err, "failed to make btrfs filesystem (out: %q)", out)
-			t.Skipf("could not mkfs.btrfs %s: %v (out: %q)", deviceName, err, string(out))
 		}
 		if out, err := exec.Command("mount", deviceName, root).CombinedOutput(); err != nil {
-			// not fatal
+			return nil, nil, errors.Wrapf(err, "failed to mount device %s (out: %q)", deviceName, out)
-			t.Skipf("could not mount %s: %v (out: %q)", deviceName, err, string(out))
 		}
 
 		snapshotter, err := NewSnapshotter(root)
 		if err != nil {
-			t.Fatal(err)
+			return nil, nil, errors.Wrap(err, "failed to create new snapshotter")
 		}
 
 		return snapshotter, func() {
 			testutil.Unmount(t, root)
-			cleanupDevice()
+			if err := cleanupDevice(); err != nil {
+				t.Errorf("Device cleanup failed: %v", err)
+			}
 		}, nil
 	}
 }

testutil/loopback_linux.go

@@ -7,19 +7,21 @@ import (
 	"os"
 	"os/exec"
 	"strings"
-	"testing"
+
+	"github.com/pkg/errors"
+	"github.com/sirupsen/logrus"
 )
 
 // NewLoopback creates a loopback device, and returns its device name (/dev/loopX), and its clean-up function.
-func NewLoopback(t *testing.T, size int64) (string, func()) {
+func NewLoopback(size int64) (string, func() error, error) {
 	// create temporary file for the disk image
 	file, err := ioutil.TempFile("", "containerd-test-loopback")
 	if err != nil {
-		t.Fatalf("could not create temporary file for loopback: %v", err)
+		return "", nil, errors.Wrap(err, "could not create temporary file for loopback")
 	}
 
 	if err := file.Truncate(size); err != nil {
-		t.Fatal(err)
+		return "", nil, errors.Wrap(err, "failed to resize temp file")
 	}
 	file.Close()
 
@@ -27,27 +29,28 @@ func NewLoopback(t *testing.T, size int64) (string, func()) {
 	losetup := exec.Command("losetup", "--find", "--show", file.Name())
 	p, err := losetup.Output()
 	if err != nil {
-		t.Fatal(err)
+		return "", nil, errors.Wrap(err, "loopback setup failed")
 	}
 
 	deviceName := strings.TrimSpace(string(p))
-	t.Logf("Created loop device %s (using %s)", deviceName, file.Name())
+	logrus.Debugf("Created loop device %s (using %s)", deviceName, file.Name())
 
-	cleanup := func() {
+	cleanup := func() error {
 		// detach device
-		t.Logf("Removing loop device %s", deviceName)
+		logrus.Debugf("Removing loop device %s", deviceName)
 		losetup := exec.Command("losetup", "--detach", deviceName)
 		err := losetup.Run()
 		if err != nil {
-			t.Error("Could not remove loop device", deviceName, err)
+			return errors.Wrapf(err, "Could not remove loop device %s", deviceName)
 		}
 
 		// remove file
-		t.Logf("Removing temporary file %s", file.Name())
+		logrus.Debugf("Removing temporary file %s", file.Name())
 		if err = os.Remove(file.Name()); err != nil {
-			t.Error(err)
+			return err
 		}
+		return nil
 	}
 
-	return deviceName, cleanup
+	return deviceName, cleanup, nil
 }