Enable custom runners (#156)

The trickiest part of ATS is the runner system.
Every customer will have their own test process, and we can't hope to
accomodate all of them. While we will try to provider the most used
runners for them, giving them the option to decide what runner they'll use
is a good idea.

These changes enable the dynamic import of runners.
It works by defining the runner in the yaml config.

Author: giovanni-guidini

codecov_cli/runners/__init__.py

@@ -1,4 +1,8 @@
 import logging
+import typing
+from importlib import import_module
+
+import click
 
 from codecov_cli.runners.dan_runner import DoAnythingNowRunner
 from codecov_cli.runners.python_standard_runner import PythonStandardRunner
@@ -11,8 +15,30 @@ class UnableToFindRunner(Exception):
     pass
 
 
-def _load_runner_from_yaml() -> LabelAnalysisRunnerInterface:
-    raise NotImplementedError()
+def _load_runner_from_yaml(plugin_dict: typing.Dict) -> LabelAnalysisRunnerInterface:
+    try:
+        module_obj = import_module(plugin_dict["module"])
+        class_obj = getattr(module_obj, plugin_dict["class"])
+    except ModuleNotFoundError:
+        click.secho(
+            f"Unable to dynamically load module {plugin_dict['module']}",
+            err=True,
+        )
+        raise
+    except AttributeError:
+        click.secho(
+            f"Unable to dynamically load class {plugin_dict['class']} from module {plugin_dict['module']}",
+            err=True,
+        )
+        raise
+    try:
+        return class_obj(**plugin_dict["params"])
+    except TypeError:
+        click.secho(
+            f"Unable to instantiate {class_obj} with parameters {plugin_dict['params']}",
+            err=True,
+        )
+        raise
 
 
 def get_runner(cli_config, runner_name) -> LabelAnalysisRunnerInterface:

tests/runners/test_runners.py

@@ -1,8 +1,11 @@
 from unittest.mock import patch
 
-from codecov_cli.runners import get_runner
+import pytest
+
+from codecov_cli.runners import _load_runner_from_yaml, get_runner
 from codecov_cli.runners.dan_runner import DoAnythingNowRunner
 from codecov_cli.runners.python_standard_runner import PythonStandardRunner
+from tests.factory import FakeRunner
 
 
 class TestRunners(object):
@@ -42,3 +45,57 @@ def test_get_runner_from_yaml(self, mock_load_runner):
         mock_load_runner.return_value = "MyRunner()"
         assert get_runner(config, "my_runner") == "MyRunner()"
         mock_load_runner.assert_called_with({"path": "path_to_my_runner"})
+
+    def test_load_runner_from_yaml(self, mocker):
+        fake_module = mocker.MagicMock(FakeRunner=FakeRunner)
+        mocker.patch("codecov_cli.runners.import_module", return_value=fake_module)
+        res = _load_runner_from_yaml(
+            {
+                "module": "mymodule.runner",
+                "class": "FakeRunner",
+                "params": {"collect_tests_response": ["list", "of", "labels"]},
+            }
+        )
+        assert isinstance(res, FakeRunner)
+        assert res.collect_tests() == ["list", "of", "labels"]
+        assert res.process_labelanalysis_result({}) == "I ran tests :D"
+
+    def test_load_runner_from_yaml_module_not_found(self, mocker):
+        def side_effect(*args, **kwargs):
+            raise ModuleNotFoundError()
+
+        mocker.patch("codecov_cli.runners.import_module", side_effect=side_effect)
+        with pytest.raises(ModuleNotFoundError):
+            _load_runner_from_yaml(
+                {
+                    "module": "mymodule.runner",
+                    "class": "FakeRunner",
+                    "params": {"collect_tests_response": ["list", "of", "labels"]},
+                }
+            )
+
+    def test_load_runner_from_yaml_class_not_found(self, mocker):
+        import tests.factory as fake_module
+
+        mocker.patch("codecov_cli.runners.import_module", return_value=fake_module)
+
+        with pytest.raises(AttributeError):
+            _load_runner_from_yaml(
+                {
+                    "module": "mymodule.runner",
+                    "class": "WrongClassName",
+                    "params": {"collect_tests_response": ["list", "of", "labels"]},
+                }
+            )
+
+    def test_load_runner_from_yaml_fail_instantiate_class(self, mocker):
+        fake_module = mocker.MagicMock(FakeRunner=FakeRunner)
+        mocker.patch("codecov_cli.runners.import_module", return_value=fake_module)
+        with pytest.raises(TypeError):
+            _load_runner_from_yaml(
+                {
+                    "module": "mymodule.runner",
+                    "class": "FakeRunner",
+                    "params": {"wrong_params": ["list", "of", "labels"]},
+                }
+            )