Add more tests

Author: HayaoSuzuki

tests/test_server_startup.py

@@ -5,6 +5,8 @@
 import time
 
 import pytest
+import requests
+from requests.exceptions import Timeout
 
 from pytest_httpserver import HTTPServer
 
@@ -58,9 +60,9 @@ def test_slow_start_server_waits_for_ready():
     server = SlowStartServer(host="localhost", port=0)
     server.expect_request("/").respond_with_data("ok")
 
-    start_time = time.time()
+    start_time = time.monotonic()
     server.start()
-    elapsed = time.time() - start_time
+    elapsed = time.monotonic() - start_time
 
     try:
         # Should have waited at least 0.5 seconds
@@ -112,3 +114,75 @@ def test_warns_when_ready_event_not_set():
             raise AssertionError("Server did not accept connections within 1 second")
     finally:
         server.stop()
+
+
+class SlowServeServer(HTTPServer):
+    """A server that delays serve_forever() but does not set ready event early.
+
+    This simulates the scenario where:
+    - bind() and listen() complete (TCP connections queue in backlog)
+    - But serve_forever() hasn't started yet (no HTTP responses)
+    """
+
+    def thread_target(self):
+        assert self.server is not None
+        # Delay before serve_forever - connections will queue but not be processed
+        time.sleep(3.0)
+        self._server_ready_event.set()
+        self.server.serve_forever()
+
+
+def test_http_request_fails_before_serve_forever_without_wait():
+    """
+    Demonstrate the race condition: TCP connects but HTTP times out.
+
+    This test shows why waiting for server readiness matters:
+    - After start(), TCP connections succeed (queued in backlog)
+    - But HTTP requests timeout because serve_forever() hasn't started
+    - With short client timeouts (common in production), this causes failures
+    """
+    # Use startup_timeout=0 to NOT wait for ready event (old behavior)
+    server = SlowServeServer(host="localhost", port=0, startup_timeout=0.0)
+    server.expect_request("/ping").respond_with_data("pong")
+
+    with pytest.warns(UserWarning, match="ready event was not set"):
+        server.start()
+
+    try:
+        # TCP connection succeeds (proves Zsolt's point about backlog)
+        sock = socket.create_connection((server.host, server.port), timeout=1)
+        sock.close()
+
+        # But HTTP request with short timeout fails!
+        # This is the actual problem in containerized environments
+        with pytest.raises(Timeout):
+            requests.get(server.url_for("/ping"), timeout=(0.5, 0.5))
+    finally:
+        server.stop()
+
+
+def test_http_request_succeeds_when_waiting_for_ready():
+    """
+    Demonstrate that waiting for ready event fixes the race condition.
+
+    With startup_timeout enabled (default), start() waits until
+    serve_forever() begins, so HTTP requests succeed immediately.
+    """
+    # Use default startup_timeout to wait for ready event
+    server = SlowServeServer(host="localhost", port=0)  # default startup_timeout=10.0
+    server.expect_request("/ping").respond_with_data("pong")
+
+    start_time = time.monotonic()
+    server.start()
+    elapsed = time.monotonic() - start_time
+
+    try:
+        # Should have waited for the slow startup
+        assert elapsed >= 3.0, f"Expected to wait >= 3.0s, but only waited {elapsed}s"
+
+        # HTTP request succeeds because serve_forever() has started
+        response = requests.get(server.url_for("/ping"), timeout=(0.5, 0.5))
+        assert response.status_code == 200
+        assert response.text == "pong"
+    finally:
+        server.stop()