diff --git a/backends/dockerclient.go b/backends/dockerclient.go
index be26bbf682..38127c4474 100644
--- a/backends/dockerclient.go
+++ b/backends/dockerclient.go
@@ -204,7 +204,7 @@ func (c *container) start(ctx *beam.Message) error {
 
 func (c *container) stop(ctx *beam.Message) error {
 	path := fmt.Sprintf("/containers/%s/stop", c.id)
-	resp, err := c.backend.client.call("POST", path, "{}")
+	resp, err := c.backend.client.call("POST", path, "")
 	if err != nil {
 		return err
 	}
diff --git a/backends/dockerclient_test.go b/backends/dockerclient_test.go
new file mode 100644
index 0000000000..4c5948893a
--- /dev/null
+++ b/backends/dockerclient_test.go
@@ -0,0 +1,186 @@
+package backends
+
+import (
+	"github.com/docker/libswarm/beam"
+
+	"fmt"
+	"io/ioutil"
+	"net/http"
+	"net/http/httptest"
+	"reflect"
+	"strings"
+	"testing"
+)
+
+type requestStub struct {
+	reqMethod string
+	reqPath   string
+	reqBody   string
+
+	resStatus int
+	resBody   string
+}
+
+func TestBackendSpawn(t *testing.T) {
+	instance(t, nil)
+}
+
+func TestAttachAndStart(t *testing.T) {
+	i := instance(t, nil)
+	_, _, err := i.Attach("")
+	if err != nil {
+		t.Fatal(err)
+	}
+	err = i.Start()
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestLs(t *testing.T) {
+	server := makeServer(t, &requestStub{
+		reqMethod: "GET",
+		reqPath:   "/containers/json",
+		resBody: `
+      [
+        {"Names": ["/foo"]},
+        {"Names": ["/bar"]}
+      ]
+    `,
+	})
+	i := instance(t, server)
+	names, err := i.Ls()
+	if err != nil {
+		t.Fatal(err)
+	}
+	expected := []string{"foo", "bar"}
+	if !reflect.DeepEqual(names, expected) {
+		t.Fatalf("expected %#v, got %#v", expected, names)
+	}
+}
+
+func TestSpawn(t *testing.T) {
+	server := makeServer(t, &requestStub{
+		reqMethod: "POST",
+		reqPath:   "/containers/create",
+		reqBody:   "{}",
+
+		resStatus: 201,
+		resBody:   "{}",
+	})
+	i := instance(t, server)
+	_, err := i.Spawn("{}")
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestAttachToChild(t *testing.T) {
+	name := "foo"
+	server := makeServer(t, &requestStub{
+		reqMethod: "GET",
+		reqPath:   fmt.Sprintf("/containers/%s/json", name),
+
+		resBody: "{}",
+	})
+	i := instance(t, server)
+	child(t, server, i, name)
+}
+
+func TestStartChild(t *testing.T) {
+	name := "foo"
+	server := makeServer(t, &requestStub{
+		reqMethod: "GET",
+		reqPath:   fmt.Sprintf("/containers/%s/json", name),
+
+		resBody: "{}",
+	}, &requestStub{
+		reqMethod: "POST",
+		reqPath:   fmt.Sprintf("/containers/%s/start", name),
+		reqBody:   "{}",
+
+		resStatus: 204,
+	})
+	i := instance(t, server)
+	c := child(t, server, i, name)
+	err := c.Start()
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestStopChild(t *testing.T) {
+	name := "foo"
+	server := makeServer(t, &requestStub{
+		reqMethod: "GET",
+		reqPath:   fmt.Sprintf("/containers/%s/json", name),
+
+		resBody: "{}",
+	}, &requestStub{
+		reqMethod: "POST",
+		reqPath:   fmt.Sprintf("/containers/%s/stop", name),
+
+		resStatus: 204,
+	})
+	i := instance(t, server)
+	c := child(t, server, i, name)
+	err := c.Stop()
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
+func makeServer(t *testing.T, stubs ...*requestStub) *httptest.Server {
+	for _, stub := range stubs {
+		stub.reqPath = fmt.Sprintf("/v1.11%s", stub.reqPath)
+	}
+
+	stubSummaries := []string{}
+	for _, stub := range stubs {
+		stubSummaries = append(stubSummaries, fmt.Sprintf("%s %s", stub.reqMethod, stub.reqPath))
+	}
+
+	return httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		for _, stub := range stubs {
+			if r.Method == stub.reqMethod && r.URL.Path == stub.reqPath {
+				body, err := ioutil.ReadAll(r.Body)
+				if err != nil {
+					t.Fatal(err)
+				}
+				if string(body) != stub.reqBody {
+					t.Fatalf("expected body: %#v, got body: %#v", stub.reqBody, string(body))
+				}
+
+				if stub.resStatus > 0 {
+					w.WriteHeader(stub.resStatus)
+				}
+				w.Write([]byte(stub.resBody))
+				return
+			}
+		}
+
+		t.Fatalf("Unexpected request: '%s %s'.\nStubs: %#v", r.Method, r.URL.Path, stubSummaries)
+	}))
+}
+
+func instance(t *testing.T, server *httptest.Server) *beam.Object {
+	url := "tcp://localhost:4243"
+	if server != nil {
+		url = strings.Replace(server.URL, "http://", "tcp://", 1)
+	}
+
+	backend := DockerClient()
+	instance, err := beam.Obj(backend).Spawn(url)
+	if err != nil {
+		t.Fatal(err)
+	}
+	return instance
+}
+
+func child(t *testing.T, server *httptest.Server, i *beam.Object, name string) *beam.Object {
+	_, child, err := i.Attach(name)
+	if err != nil {
+		t.Fatal(err)
+	}
+	return child
+}