Simplify test by removing ThreadPool

tests/test_auth.py

@@ -1,7 +1,7 @@
 import re
 import pytest
 import tornado.web
-from concurrent.futures import ThreadPoolExecutor
+import tornado.gen
 
 
 @pytest.mark.gen_test
@@ -17,19 +17,22 @@ def test_redirects_when_not_logged_in(http_client, base_url):
 
 @pytest.mark.gen_test
 def test_login_with_valid_bearer_token(app, monkeypatch, http_client, base_url):
-    with ThreadPoolExecutor(max_workers=1) as executor:
-        monkeypatch.setattr(
-            "atst.handlers.login.Login._validate_login_token",
-            lambda c,t: executor.submit(lambda: True),
-        )
-        response = yield http_client.fetch(
-            base_url + "/login?bearer-token=abc-123",
-            follow_redirects=False,
-            raise_error=False
-        )
-        assert response.headers["Set-Cookie"].startswith("atst")
-        assert response.headers['Location'] == '/home'
-        assert response.code == 302
+    @tornado.gen.coroutine
+    def _validate_login_token(c, t):
+        return True
+
+    monkeypatch.setattr(
+        "atst.handlers.login.Login._validate_login_token",
+        _validate_login_token
+    )
+    response = yield http_client.fetch(
+        base_url + "/login?bearer-token=abc-123",
+        follow_redirects=False,
+        raise_error=False
+    )
+    assert response.headers["Set-Cookie"].startswith("atst")
+    assert response.headers['Location'] == '/home'
+    assert response.code == 302
 
 
 @pytest.mark.gen_test