tests: add a pytest hook for handling unhandled exception in closures

In PyGObject when an exception is raised in a closure called from C then
the error gets passed to sys.excepthook (on the main thread at least)
and the error is by default printed to stdout. Since pytest by default
hides stdout, errors can be easily missed now.

To make these errors more visible add a test wrapper which checks
sys.excepthook for unhandled exceptions and reraises them.
This makes the tests fail and as a bonus also shows the right
stack trace instead of just the error message.

1 files changed, 31 insertions, 0 deletions

diff --git a/tests/conftest.py b/tests/conftest.py
new file mode 100644
index 00000000..f69405d4
--- /dev/null
+++ b/tests/conftest.py
@@ -0,0 +1,31 @@
+# -*- coding: utf-8 -*-
+
+import sys
+
+import pytest
+
+from .compathelper import reraise
+
+
+@pytest.hookimpl(hookwrapper=True)
+def pytest_runtest_call(item):
+    """A pytest hook which takes over sys.excepthook and raises any uncaught
+    exception (with PyGObject this happesn often when we get called from C,
+    like any signal handler, vfuncs tc)
+    """
+
+    assert sys.excepthook is sys.__excepthook__
+
+    exceptions = []
+
+    def on_hook(type_, value, tback):
+        exceptions.append((type_, value, tback))
+
+    sys.excepthook = on_hook
+    try:
+        yield
+    finally:
+        assert sys.excepthook in (on_hook, sys.__excepthook__)
+        sys.excepthook = sys.__excepthook__
+        if exceptions:
+            reraise(*exceptions[0])