diff --git a/client/client_mock_test.go b/client/client_mock_test.go
new file mode 100644
index 000000000..c3dfc1704
--- /dev/null
+++ b/client/client_mock_test.go
@@ -0,0 +1,42 @@
+package client
+
+import (
+	"bytes"
+	"encoding/json"
+	"io/ioutil"
+	"net/http"
+
+	"github.com/alibaba/pouch/apis/types"
+)
+
+type transportFunc func(*http.Request) (*http.Response, error)
+
+func (transFunc transportFunc) RoundTrip(req *http.Request) (*http.Response, error) {
+	return transFunc(req)
+}
+
+func newMockClient(handler func(*http.Request) (*http.Response, error)) *http.Client {
+	return &http.Client{
+		Transport: transportFunc(handler),
+	}
+}
+
+func errorMockResponse(statusCode int, message string) func(req *http.Request) (*http.Response, error) {
+	return func(req *http.Request) (*http.Response, error) {
+		header := http.Header{}
+		header.Set("Content-Type", "application/json")
+
+		body, err := json.Marshal(&types.Error{
+			Message: message,
+		})
+		if err != nil {
+			return nil, err
+		}
+
+		return &http.Response{
+			StatusCode: statusCode,
+			Body:       ioutil.NopCloser(bytes.NewReader(body)),
+			Header:     header,
+		}, nil
+	}
+}
diff --git a/client/container.go b/client/container.go
index 06b2ec9a2..ede80e0cb 100644
--- a/client/container.go
+++ b/client/container.go
@@ -37,19 +37,6 @@ func (client *APIClient) ContainerCreate(ctx context.Context, config types.Conta
 	return container, err
 }
 
-// ContainerStart starts a created container.
-func (client *APIClient) ContainerStart(ctx context.Context, name, detachKeys string) error {
-	q := url.Values{}
-	if detachKeys != "" {
-		q.Set("detachKeys", detachKeys)
-	}
-
-	resp, err := client.post(ctx, "/containers/"+name+"/start", q, nil, nil)
-	ensureCloseReader(resp)
-
-	return err
-}
-
 // ContainerStop stops a container.
 func (client *APIClient) ContainerStop(ctx context.Context, name string, timeout string) error {
 	q := url.Values{}
diff --git a/client/container_start.go b/client/container_start.go
new file mode 100644
index 000000000..1c448af91
--- /dev/null
+++ b/client/container_start.go
@@ -0,0 +1,19 @@
+package client
+
+import (
+	"context"
+	"net/url"
+)
+
+// ContainerStart starts a created container.
+func (client *APIClient) ContainerStart(ctx context.Context, name, detachKeys string) error {
+	q := url.Values{}
+	if detachKeys != "" {
+		q.Set("detachKeys", detachKeys)
+	}
+
+	resp, err := client.post(ctx, "/containers/"+name+"/start", q, nil, nil)
+	ensureCloseReader(resp)
+
+	return err
+}
diff --git a/client/container_start_test.go b/client/container_start_test.go
new file mode 100644
index 000000000..3964974a1
--- /dev/null
+++ b/client/container_start_test.go
@@ -0,0 +1,50 @@
+package client
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"net/http"
+	"strings"
+	"testing"
+)
+
+func TestContainerStartError(t *testing.T) {
+	client := &APIClient{
+		HTTPCli: newMockClient(errorMockResponse(http.StatusInternalServerError, "Server error")),
+	}
+	err := client.ContainerStart(context.Background(), "nothing", "")
+	if err == nil || !strings.Contains(err.Error(), "Server error") {
+		t.Fatalf("expected a Server Error, got %v", err)
+	}
+}
+
+func TestContainerStart(t *testing.T) {
+	expectedURL := "/containers/container_id/start"
+
+	httpClient := newMockClient(func(req *http.Request) (*http.Response, error) {
+		if !strings.HasPrefix(req.URL.Path, expectedURL) {
+			return nil, fmt.Errorf("Expected URL '%s', got '%s'", expectedURL, req.URL)
+		}
+		if req.Header.Get("Content-Type") == "application/json" {
+			var startConfig interface{}
+			if err := json.NewDecoder(req.Body).Decode(&startConfig); err != nil {
+				return nil, fmt.Errorf("failed to parse json: %v", err)
+			}
+		}
+		return &http.Response{
+			StatusCode: http.StatusOK,
+			Body:       ioutil.NopCloser(bytes.NewReader([]byte(""))),
+		}, nil
+	})
+
+	client := &APIClient{
+		HTTPCli: httpClient,
+	}
+
+	if err := client.ContainerStart(context.Background(), "container_id", ""); err != nil {
+		t.Fatal(err)
+	}
+}