register_routes() plugin hook (#819)

Fixes #215

tests/test_plugins.py

@@ -544,3 +544,18 @@ def test_actor_json(app_client):
     assert {"actor": {"id": "bot2", "1+1": 2}} == app_client.get(
         "/-/actor.json/?_bot2=1"
     ).json
+
+
+@pytest.mark.parametrize(
+    "path,body", [("/one/", "2"), ("/two/Ray?greeting=Hail", "Hail Ray"),]
+)
+def test_register_routes(app_client, path, body):
+    response = app_client.get(path)
+    assert 200 == response.status
+    assert body == response.text
+
+
+def test_register_routes_asgi(app_client):
+    response = app_client.get("/three/")
+    assert {"hello": "world"} == response.json
+    assert "1" == response.headers["x-three"]