qemu-arm64: add unit test for func appendImage on aarch64

Since we overrided the func appendImage for aarch64, we should also
provide related unit test.

Fixes: #843

Signed-off-by: Penny Zheng <penny.zheng@arm.com>

virtcontainers/qemu_arm64_test.go

@@ -125,3 +125,33 @@ func TestQemuArm64AppendBridges(t *testing.T) {
 
 	assert.Equal(expectedOut, devices)
 }
+
+func TestQemuArm64AppendImage(t *testing.T) {
+	var devices []govmmQemu.Device
+	assert := assert.New(t)
+	arm64 := newTestQemu(QemuVirt)
+
+	f, err := ioutil.TempFile("", "img")
+	assert.NoError(err)
+	defer func() { _ = f.Close() }()
+	defer func() { _ = os.Remove(f.Name()) }()
+
+	imageStat, err := f.Stat()
+	assert.NoError(err)
+
+	expectedOut := []govmmQemu.Device{
+		govmmQemu.Object{
+			Driver:   govmmQemu.NVDIMM,
+			Type:     govmmQemu.MemoryBackendFile,
+			DeviceID: "nv0",
+			ID:       "mem0",
+			MemPath:  f.Name(),
+			Size:     (uint64)(imageStat.Size()),
+		},
+	}
+
+	devices, err = arm64.appendImage(devices, f.Name())
+	assert.NoError(err)
+
+	assert.Equal(expectedOut, devices)
+}