Fix is_masked method on systemd service (#569)

systemctl is-enabled my-service` rc is 1 if the service is masked.
Add test for is_masked method on systemd service

Co-authored-by: Philippe Pepiot <[email protected]>

Author: dorianm

test/test_modules.py

@@ -132,6 +132,15 @@ def test_ssh_service(host, docker_image):
         assert ssh.is_enabled
 
 
+def test_service_systemd_mask(host):
+    ssh = host.service("ssh")
+    assert not ssh.is_masked
+    host.run("systemctl mask ssh")
+    assert ssh.is_masked
+    host.run("systemctl unmask ssh")
+    assert not ssh.is_masked
+
+
 @pytest.mark.parametrize("name,running,enabled", [
     ("ntp", False, True),
     ("salt-minion", False, False),

testinfra/modules/service.py

@@ -153,7 +153,7 @@ def is_valid(self):
     @property
     def is_masked(self):
         cmd = self.run_test("systemctl is-enabled %s", self.name)
-        return cmd.rc == 0 and cmd.stdout.strip() == "masked"
+        return cmd.stdout.strip() == "masked"
 
 
 class UpstartService(SysvService):