add a test for imap capabilities offered from chatmail

cmdeploy/src/cmdeploy/tests/online/test_0_login.py

@@ -15,6 +15,13 @@ def test_init(tmp_path, maildomain):
     assert config.mail_domain == maildomain
 
 
+def test_capabilities(imap):
+    imap.connect()
+    capas = imap.conn.capabilities
+    assert "XCHATMAIL" in capas
+    assert "XDELTAPUSH" in capas
+
+
 def test_login_basic_functioning(imap_or_smtp, gencreds, lp):
     """Test a) that an initial login creates a user automatically
     and b) verify we can also login a second time with the same password