--liveserver-verbose and --liveserver-debug command-line arguments

docs/changelog.rst

@@ -1,6 +1,16 @@
 Changelog
 =========
 
+vunreleased ()
+--------------
+
+Improvements
+^^^^^^^^^^^^
+
+* ``--liveserver-verbose`` command-line parameter, which allows to see
+  logs from live_server on the standard output, including tracebacks.
+  Useful for debugging.
+
 v4.5.2 (2021-12-07)
 -------------------
 

docs/helpers.rst

@@ -371,6 +371,17 @@ depends on the ``transactional_db`` fixture. If tests depend on data
 created in data migrations, you should add the
 ``django_db_serialized_rollback`` fixture.
 
+You can also use ``--liveserver-verbose`` command-line argument, to outputs
+the liveserver logs to the standard output, including tracebacks. This is
+useful for debugging live server behaviour and environment-related problems.
+Take note, logs will be written to standard output, which is being supressed
+by pytest by default, so you will need to use ``-s`` or ``--capture=no``
+parameter too.
+
+And if your live server still keeps acting weird, there is a switch called
+``--liveserver-debug`` which drops into debugger in the console
+whenever traceback occurs in a live server page.
+
 .. note:: Combining database access fixtures.
 
   When using multiple database fixtures together, only one of them is

pytest_django/fixtures.py

@@ -536,7 +536,14 @@ def live_server(request):
         "DJANGO_LIVE_TEST_SERVER_ADDRESS"
     ) or "localhost"
 
-    server = live_server_helper.LiveServer(addr)
+    live_server_class = live_server_helper.LiveServer
+    if request.config.getvalue("liveserver_verbose") is True:
+        live_server_class = live_server_helper.VerboseLiveServer
+
+        if request.config.getvalue("liveserver_debug") is True:
+            live_server_class = live_server_helper.VerboseDebuggingLiveServer
+
+    server = live_server_class(addr)
     request.addfinalizer(server.stop)
     return server
 

pytest_django/live_server_helper.py

@@ -8,9 +8,12 @@ class LiveServer:
     The ``live_server`` fixture handles creation and stopping.
     """
 
+    def get_live_server_thread_class(self):
+        from django.test.testcases import LiveServerThread
+        return LiveServerThread
+
     def __init__(self, addr: str) -> None:
         from django.db import connections
-        from django.test.testcases import LiveServerThread
         from django.test.utils import modify_settings
 
         liveserver_kwargs = {}  # type: Dict[str, Any]
@@ -42,7 +45,9 @@ def __init__(self, addr: str) -> None:
             host = addr
         else:
             liveserver_kwargs["port"] = int(port)
-        self.thread = LiveServerThread(host, **liveserver_kwargs)
+
+        live_server_thread_class = self.get_live_server_thread_class()
+        self.thread = live_server_thread_class(host, **liveserver_kwargs)
 
         self._live_server_modified_settings = modify_settings(
             ALLOWED_HOSTS={"append": host}
@@ -79,3 +84,15 @@ def __add__(self, other) -> str:
 
     def __repr__(self) -> str:
         return "<LiveServer listening at %s>" % self.url
+
+
+class VerboseLiveServer(LiveServer):
+    def get_live_server_thread_class(self):
+        from .verbose_live_server import VerboseLiveServerThread
+        return VerboseLiveServerThread
+
+
+class VerboseDebuggingLiveServer(LiveServer):
+    def get_live_server_thread_class(self):
+        from .verbose_live_server import VerboseDebuggingLiveServerThread
+        return VerboseDebuggingLiveServerThread

pytest_django/plugin.py

@@ -124,6 +124,23 @@ def pytest_addoption(parser) -> None:
     parser.addini(
         SETTINGS_MODULE_ENV, "Django settings module to use by pytest-django."
     )
+    group.addoption(
+        "--liveserver-verbose",
+        "--liveserver_verbose",
+        action="store_true",
+        dest="liveserver_verbose",
+        default=False,
+        help="Enable verbose logging for live_server fixture",
+    )
+    group.addoption(
+        "--liveserver-debug",
+        "--liveserver_debug",
+        action="store_true",
+        dest="liveserver_debug",
+        default=False,
+        help="Drops into debugger on tracebacks in live_server "
+             "(only if used with --liveserver-verbose)"
+    )
 
     parser.addini(
         "django_find_project",

pytest_django/verbose_live_server.py

@@ -0,0 +1,37 @@
+import sys
+import traceback
+
+from django.core.servers.basehttp import ThreadedWSGIServer, WSGIRequestHandler
+from django.test.testcases import LiveServerThread
+
+
+class VerboseWSGIRequestHandler(WSGIRequestHandler):
+    debug_on_traceback = False
+
+    def handle_uncaught_exception(self, request, resolver, exc_info):
+        traceback.print_tb(exc_info[2], file=sys.stderr)
+        if self.debug_on_traceback:
+            import pytest
+            pytest.set_trace()
+
+        return super(VerboseWSGIRequestHandler, self).handle_uncaught_exception(
+            request, resolver, exc_info)
+
+
+class VerboseDebuggingWSGIRequestHandler(VerboseWSGIRequestHandler):
+    debug_on_traceback = True
+
+
+class VerboseLiveServerThread(LiveServerThread):
+    request_handler_class = VerboseWSGIRequestHandler
+
+    def _create_server(self):
+        return ThreadedWSGIServer(
+            (self.host, self.port),
+            self.request_handler_class,
+            allow_reuse_address=False
+        )
+
+
+class VerboseDebuggingLiveServerThread(VerboseLiveServerThread):
+    request_handler_class = VerboseDebuggingWSGIRequestHandler