daemon: setupFakeDaemon(): add fakeImageService

To prevent a panic happening when running tests:

    === FAIL: daemon TestTmpfsDevShmNoDupMount (0.01s)
    panic: runtime error: invalid memory address or nil pointer dereference [recovered]
        panic: runtime error: invalid memory address or nil pointer dereference
    [signal SIGSEGV: segmentation violation code=0x1 addr=0x120 pc=0x261a373]

    goroutine 134 [running]:
    testing.tRunner.func1.2({0x28baf20, 0x3ea8000})
        /usr/local/go/src/testing/testing.go:1526 +0x24e
    testing.tRunner.func1()
        /usr/local/go/src/testing/testing.go:1529 +0x39f
    panic({0x28baf20, 0x3ea8000})
        /usr/local/go/src/runtime/panic.go:884 +0x213
    github.com/docker/docker/daemon.(*Daemon).createSpec(0xc0006e0000, {0x2ea5588, 0xc00012a008}, 0xc0003b5900)
        /go/src/github.com/docker/docker/daemon/oci_linux.go:1060 +0xf33
    github.com/docker/docker/daemon.TestTmpfsDevShmNoDupMount(0xc000b781a0?)
        /go/src/github.com/docker/docker/daemon/oci_linux_test.go:77 +0x20a
    testing.tRunner(0xc000b78340, 0x2c74210)
        /usr/local/go/src/testing/testing.go:1576 +0x10b
    created by testing.(*T).Run
        /usr/local/go/src/testing/testing.go:1629 +0x3ea

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

daemon/oci_linux_test.go

@@ -33,6 +33,7 @@ func setupFakeDaemon(t *testing.T, c *container.Container) *Daemon {
 		configStore:   &config.Config{},
 		linkIndex:     newLinkIndex(),
 		netController: netController,
+		imageService:  &fakeImageService{},
 	}
 
 	c.Root = root
@@ -51,6 +52,14 @@ func setupFakeDaemon(t *testing.T, c *container.Container) *Daemon {
 	return d
 }
 
+type fakeImageService struct {
+	ImageService
+}
+
+func (i *fakeImageService) StorageDriver() string {
+	return "overlay"
+}
+
 func cleanupFakeContainer(c *container.Container) {
 	_ = os.RemoveAll(c.Root)
 }