client: Add helper function which checks if an image is unpacked

Signed-off-by: Jess Valarezo <valarezo.jessica@gmail.com>

image_test.go

@@ -0,0 +1,58 @@
+package containerd
+
+import (
+	"runtime"
+	"testing"
+
+	"github.com/containerd/containerd/errdefs"
+)
+
+func TestImageIsUnpacked(t *testing.T) {
+	if runtime.GOOS == "windows" {
+		t.Skip()
+	}
+
+	const imageName = "docker.io/library/busybox:latest"
+	ctx, cancel := testContext()
+	defer cancel()
+
+	client, err := newClient(t, address)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer client.Close()
+
+	// Cleanup
+	err = client.ImageService().Delete(ctx, imageName)
+	if err != nil && !errdefs.IsNotFound(err) {
+		t.Fatal(err)
+	}
+
+	// By default pull does not unpack an image
+	image, err := client.Pull(ctx, imageName)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// Check that image is not unpacked
+	unpacked, err := image.IsUnpacked(ctx, DefaultSnapshotter)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if unpacked {
+		t.Fatalf("image should not be unpacked")
+	}
+
+	// Check that image is unpacked
+	err = image.Unpack(ctx, DefaultSnapshotter)
+	if err != nil {
+		t.Fatal(err)
+	}
+	unpacked, err = image.IsUnpacked(ctx, DefaultSnapshotter)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !unpacked {
+		t.Fatalf("image should be unpacked")
+	}
+}