Adds Marathon support.

Co-authored-by: Julien Salleyron <julien@containo.us>

provider/marathon/fake_client_test.go

@@ -0,0 +1,24 @@
+package marathon
+
+import (
+	"errors"
+
+	"github.com/containous/traefik/provider/marathon/mocks"
+	"github.com/gambol99/go-marathon"
+	"github.com/stretchr/testify/mock"
+)
+
+type fakeClient struct {
+	mocks.Marathon
+}
+
+func newFakeClient(applicationsError bool, applications marathon.Applications) *fakeClient {
+	// create an instance of our test object
+	fakeClient := new(fakeClient)
+	if applicationsError {
+		fakeClient.On("Applications", mock.Anything).Return(nil, errors.New("fake Marathon server error"))
+	} else {
+		fakeClient.On("Applications", mock.Anything).Return(&applications, nil)
+	}
+	return fakeClient
+}