test: daemonizer

.gitignore

@@ -9,3 +9,4 @@ htmlcov/
 \~/
 settings.env
 log
+test_pid

requirements-dev.txt

@@ -1,7 +1,7 @@
 -r requirements.txt
-pytest==3.2.3
+pytest==5.0.1
+pytest-cov==2.7.1
 pytest-mock==1.10.4
 freezegun==0.2.3
-pytest-cov==2.5.1
-coverage==4.5.2
+coverage==4.5.3
 flake8==3.7.7

tests/test_daemon.py

@@ -0,0 +1,78 @@
+import os
+import signal
+
+import pytest
+
+from rerwatcher.daemon import Daemon
+
+base_dir = os.getcwd()
+pidfile = f'{base_dir}/test_pid'
+
+
+class DaemonApp(Daemon):
+    def __init__(self):
+        super(DaemonApp, self).__init__(
+            pidfile=pidfile,
+            app_name='TestApp'
+        )
+
+    def run(self):
+        print('Daemon working!')
+
+
+# TODO: find a better way to test the real case.
+def test_daemon(mocker, capsys):
+    os = mocker.patch('rerwatcher.daemon.os', **{
+        'fork.return_value': 0,
+        'path.exists.side_effect': [False, True],
+        'getpid.return_value': 42,
+    })
+    mocker.patch('rerwatcher.daemon.sys')
+    daemon_app = DaemonApp()
+
+    daemon_app.start()
+    daemon_app.stop()
+
+    assert os.fork.call_count == 2
+    captured = capsys.readouterr()
+    assert 'Daemon working!\n' == captured.out
+    assert os.remove.called_once_with(pidfile)
+    assert os.kill.called_once_with(42, signal.SIGTERM)
+
+
+def test_daemon_do_not_start_if_os_fork_fails(mocker):
+    mocker.patch('rerwatcher.daemon.os', **{
+        'path.exists.return_value': False,
+        'fork.return_value': 1,
+    })
+    daemon_app = DaemonApp()
+
+    with pytest.raises(SystemExit):
+        daemon_app.start()
+
+
+def test_daemon_do_not_start_if_os_fork2_fails(mocker):
+    mocker.patch('rerwatcher.daemon.os', **{
+        'path.exists.return_value': False,
+        'fork.side_effect': [0, 1],
+    })
+    daemon_app = DaemonApp()
+
+    with pytest.raises(SystemExit):
+        daemon_app.start()
+
+
+def test_daemon_do_not_start_if_already_running(mocker):
+    mocker.patch('rerwatcher.daemon.os.path.exists', return_value=True)
+    daemon_app = DaemonApp()
+
+    with pytest.raises(RuntimeError):
+        daemon_app.start()
+
+
+def test_daemon_do_not_stop_if_not_running(mocker):
+    mocker.patch('rerwatcher.daemon.os.path.exists', return_value=False)
+    daemon_app = DaemonApp()
+
+    with pytest.raises(SystemExit):
+        daemon_app.stop()