diff --git a/modoboa/core/mocks.py b/modoboa/core/mocks.py
new file mode 100644
index 000000000..bd644364d
--- /dev/null
+++ b/modoboa/core/mocks.py
@@ -0,0 +1,29 @@
+"""Mocks used for testing."""
+
+import httmock
+
+
+# Modoboa API mocks
+
+@httmock.urlmatch(
+    netloc=r"api\.modoboa\.org$", path=r"^/1/instances/search/", method="post")
+def modo_api_instance_search(url, request):
+    """Return empty response."""
+    return {"status_code": 404}
+
+
+@httmock.urlmatch(
+    netloc=r"api\.modoboa\.org$", path=r"^/1/instances/", method="post")
+def modo_api_instance_create(url, request):
+    """Simulate successful creation."""
+    return {
+        "status_code": 201,
+        "content": {"pk": 100}
+    }
+
+
+@httmock.urlmatch(
+    netloc=r"api\.modoboa\.org$", path=r"^/1/instances/.+/", method="put")
+def modo_api_instance_update(url, request):
+    """Simulate successful update."""
+    return {"status_code": 200}
diff --git a/modoboa/core/tests.py b/modoboa/core/tests.py
index cc27441e4..4e2a652bf 100644
--- a/modoboa/core/tests.py
+++ b/modoboa/core/tests.py
@@ -1,5 +1,8 @@
 """Tests for core application."""
 
+import httmock
+
+from django.core import management
 from django.core.urlresolvers import reverse
 from django.test import override_settings
 
@@ -8,6 +11,7 @@ from modoboa.lib import parameters
 from modoboa.lib.tests import ModoTestCase
 
 from . import factories
+from . import mocks
 from . import models
 
 
@@ -240,3 +244,15 @@ class APIAccessFormTestCase(ModoTestCase):
         self.ajax_post(url, {"enable_api_access": False})
         user = models.User.objects.get(username="admin")
         self.assertFalse(hasattr(user, "auth_token"))
+
+
+class APICommunicationTestCase(ModoTestCase):
+    """Check communication with the API."""
+
+    def test_management_command(self):
+        """Check command."""
+        with httmock.HTTMock(
+                mocks.modo_api_instance_search,
+                mocks.modo_api_instance_create,
+                mocks.modo_api_instance_update):
+            management.call_command("communicate_with_public_api")
diff --git a/test-requirements.txt b/test-requirements.txt
index e37c21246..a1b4ef1c5 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -1,3 +1,3 @@
 factory-boy>=2.4
 testfixtures==4.7.0
-
+httmock==1.2.5