Add configuration to collect types from pytest runs

tests/conftest.py

@@ -20,3 +20,30 @@ def pytest_generate_tests(metafunc):
             "pytest_params",
             parametrizations,
         )
+
+
+# TODO: Remove these before merge
+def pytest_collection_finish(session):
+    """Handle the pytest collection finish hook: configure pyannotate.
+    Explicitly delay importing `collect_types` until all tests have
+    been collected.  This gives gevent a chance to monkey patch the
+    world before importing pyannotate.
+    """
+    from pyannotate_runtime import collect_types
+
+    collect_types.init_types_collection()
+
+
+@pytest.fixture(autouse=True)
+def collect_types_fixture():
+    from pyannotate_runtime import collect_types
+
+    collect_types.start()
+    yield
+    collect_types.stop()
+
+
+def pytest_sessionfinish(session, exitstatus):
+    from pyannotate_runtime import collect_types
+
+    collect_types.dump_stats("type_info.json")