rework plugin loading

tests/unit/plugins/reporter_test.py

@@ -0,0 +1,74 @@
+import argparse
+
+import pytest
+
+from flake8._compat import importlib_metadata
+from flake8.formatting import default
+from flake8.plugins import finder
+from flake8.plugins import reporter
+
+
+def _opts(**kwargs):
+    kwargs.setdefault("quiet", 0),
+    kwargs.setdefault("color", "never")
+    kwargs.setdefault("output_file", None)
+    return argparse.Namespace(**kwargs)
+
+
+@pytest.fixture
+def reporters():
+    def _plugin(name, cls):
+        return finder.LoadedPlugin(
+            finder.Plugin(
+                "flake8",
+                "123",
+                importlib_metadata.EntryPoint(
+                    name, f"{cls.__module__}:{cls.__name__}", "flake8.report"
+                ),
+            ),
+            cls,
+            {"options": True},
+        )
+
+    return {
+        "default": _plugin("default", default.Default),
+        "pylint": _plugin("pylint", default.Pylint),
+        "quiet-filename": _plugin("quiet-filename", default.FilenameOnly),
+        "quiet-nothing": _plugin("quiet-nothing", default.Nothing),
+    }
+
+
+def test_make_formatter_default(reporters):
+    ret = reporter.make(reporters, _opts(format="default"))
+    assert isinstance(ret, default.Default)
+    assert ret.error_format == default.Default.error_format
+
+
+def test_make_formatter_quiet_filename(reporters):
+    ret = reporter.make(reporters, _opts(format="default", quiet=1))
+    assert isinstance(ret, default.FilenameOnly)
+
+
+@pytest.mark.parametrize("quiet", (2, 3))
+def test_make_formatter_very_quiet(reporters, quiet):
+    ret = reporter.make(reporters, _opts(format="default", quiet=quiet))
+    assert isinstance(ret, default.Nothing)
+
+
+def test_make_formatter_custom(reporters):
+    ret = reporter.make(reporters, _opts(format="pylint"))
+    assert isinstance(ret, default.Pylint)
+
+
+def test_make_formatter_format_string(reporters, caplog):
+    ret = reporter.make(reporters, _opts(format="hi %(code)s"))
+    assert isinstance(ret, default.Default)
+    assert ret.error_format == "hi %(code)s"
+
+    assert caplog.record_tuples == [
+        (
+            "flake8.plugins.reporter",
+            30,
+            "'hi %(code)s' is an unknown formatter.  Falling back to default.",
+        )
+    ]