Better error handling for doveadm call.

modoboa/core/password_hashers/__init__.py

@@ -42,12 +42,16 @@ def get_dovecot_schemes():
     :return: A list of supported '{SCHEME}'
     """
     schemes = getattr(settings, "DOVECOT_SUPPORTED_SCHEMES", None)
+    default_schemes = "MD5-CRYPT PLAIN"
 
     if not schemes:
         try:
-            _, schemes = doveadm_cmd("pw -l")
+            retcode, schemes = doveadm_cmd("pw -l")
         except OSError:
-            schemes = "MD5-CRYPT PLAIN"
+            schemes = default_schemes
+        else:
+            if retcode:
+                schemes = default_schemes
 
     return ["{{{}}}".format(smart_text(scheme))
             for scheme in schemes.split()]

modoboa/core/tests/test_authentication.py

@@ -171,9 +171,16 @@ class AuthenticationTestCase(ModoTestCase):
         self.assertEqual(parameters.memory_cost, 1000)
         self.assertEqual(parameters.parallelism, 2)
 
-    @override_settings(DOVEADM_LOOKUP_PATH=[DOVEADM_TEST_PATH])
-    def test_dovecot_supported_schemes(self):
+    @mock.patch("modoboa.lib.sysutils.exec_cmd")
+    def test_dovecot_supported_schemes(self, exec_cmd_mock):
         """Validate Dovecot supported schemes with fake command output."""
+        exec_cmd_mock.return_value = (
+            0,
+            "MD5 MD5-CRYPT SHA SHA1 SHA256 SHA512 SMD5 SSHA SSHA256 SSHA512 "
+            "PLAIN CLEAR CLEARTEXT PLAIN-TRUNC CRAM-MD5 SCRAM-SHA-1 HMAC-MD5 "
+            "DIGEST-MD5 PLAIN-MD4 PLAIN-MD5 LDAP-MD5 LANMAN NTLM OTP SKEY RPA "
+            "PBKDF2 CRYPT SHA256-CRYPT SHA512-CRYPT"
+        )
         supported_schemes = get_dovecot_schemes()
         self.assertEqual(supported_schemes,
                          ["{MD5}",