Added IrisSystemThread.get_command() helper and system tests.

_USE_SUDO is to make testing easier.

tests/test_system.py

@@ -0,0 +1,98 @@
+import pathlib, pytest, subprocess
+from unittest import mock
+
+from mopidy_iris.system import IrisSystemThread, IrisSystemMissingError, IrisSystemPermissionError
+
+
+def test_system_sh_path():
+    iris_system = IrisSystemThread('foo', None)
+    assert iris_system.script_path.is_file()
+    assert iris_system.script_path.name == "system.sh"
+
+
+def test_can_run():
+    iris_system = IrisSystemThread('foo', None)
+    iris_system._USE_SUDO = False
+    assert iris_system.can_run() is True
+
+@pytest.fixture
+def popen_mock():
+    patcher = mock.patch("subprocess.Popen", spec=True)
+    yield patcher.start()
+    patcher.stop()
+
+@pytest.fixture
+def process_mock(popen_mock):
+    mock_process = popen_mock.return_value
+    mock_process.communicate.return_value = ('', None)
+    mock_process.wait.return_value = 0
+    yield mock_process
+
+def test_can_run_args(popen_mock, process_mock):
+    IrisSystemThread('foo', None).can_run()
+    popen_mock.assert_called_once_with(
+        mock.ANY,
+        shell=True,
+        stderr=subprocess.PIPE,
+        stdout=subprocess.PIPE
+    )
+
+def test_can_run_uses_sudo_non_interactive(popen_mock, process_mock):
+    IrisSystemThread('foo', None).can_run()
+    
+    popen_mock.assert_called_once()
+    assert popen_mock.call_args[0][0].startswith(b"sudo -n ")
+
+
+def test_can_run_calls_script_check(popen_mock, process_mock):
+    IrisSystemThread('foo', None).can_run()
+
+    assert popen_mock.call_args[0][0].endswith(b"system.sh check")
+
+
+def test_can_run_script_missing_raises(tmp_path, caplog):
+    iris_system = IrisSystemThread('foo', None)
+    iris_system.script_path = tmp_path
+
+    with pytest.raises(IrisSystemMissingError) as excinfo:
+        iris_system.can_run()
+
+    error_message = "Unable to access %s." % tmp_path.as_uri()
+    assert error_message in str(excinfo.value)
+    assert error_message in caplog.text
+
+
+def test_can_run_sudo_refused_raises(popen_mock, process_mock, caplog):
+    process_mock.wait.return_value = 1
+    iris_system = IrisSystemThread('foo', None)
+
+    with pytest.raises(IrisSystemPermissionError) as excinfo:
+        iris_system.can_run()
+
+    error_message = (
+        "Password-less access to %s was refused. "
+        "Check your /etc/sudoers file." % iris_system.script_path.as_uri()
+    )
+    assert error_message in str(excinfo.value)
+    assert error_message in caplog.text
+
+
+def test_run_args(popen_mock, process_mock):
+    iris_system = IrisSystemThread('foo', mock.Mock())
+    iris_system.can_run = mock.Mock(return_value = True)
+    iris_system.run()
+
+    popen_mock.assert_called_once_with(
+        mock.ANY,
+        stderr=subprocess.PIPE,
+        stdout=subprocess.PIPE
+    )
+
+
+def test_run_uses_sudo(popen_mock, process_mock):
+    iris_system = IrisSystemThread('foo', mock.Mock())
+    iris_system.can_run = mock.Mock(return_value = True)
+    iris_system.run()
+    
+    popen_mock.assert_called_once()
+    assert popen_mock.call_args[0][0][0] == b"sudo"