Add tests for exception leaking.

BadSingleton · lostmsu · commit ca1a72b1bd7e · 2022-01-24T18:25:01.000-08:00
Originally from PR #1402. The underlying bug is now fixed, but the tests are atill applicable.
diff --git a/src/testing/exceptiontest.cs b/src/testing/exceptiontest.cs
@@ -1,3 +1,4 @@
+using Python.Runtime;
 using System;
 using System.Collections;
 using System.Collections.Generic;
@@ -81,6 +82,40 @@ public static void ThrowChainedExceptions()
                 throw new Exception("Outer exception", exc2);
             }
         }
+        
+        public static IntPtr DoThrowSimple()
+        {
+            using (Py.GIL())
+            {
+                dynamic builtins = Py.Import("builtins");
+                var typeErrorType = new PyType(builtins.TypeError);
+                var pyerr = new PythonException(typeErrorType, value:null, traceback:null, "Type error, the first", innerException:null);
+                throw new ArgumentException("Bogus bad parameter", pyerr);
+
+            }
+        }
+
+        public static void DoThrowWithInner()
+        {
+            using(Py.GIL())
+            {
+                // create a TypeError
+                dynamic builtins = Py.Import("builtins");
+                var pyerrFirst = new PythonException(new PyType(builtins.TypeError), value:null, traceback:null, "Type error, the first", innerException:null);
+
+                // Create an ArgumentException, but as a python exception, with the previous type error as the inner exception
+                var argExc = new ArgumentException("Bogus bad parameter", pyerrFirst);
+                var argExcPyObj = argExc.ToPython();
+                var pyArgExc = new PythonException(argExcPyObj.GetPythonType(), value:null, traceback:null, argExc.Message, innerException:argExc.InnerException);
+                // This object must be disposed explicitly or else we get a false-positive leak.
+                argExcPyObj.Dispose();
+                
+                // Then throw a TypeError with the ArgumentException-as-python-error exception as inner.
+                var pyerrSecond = new PythonException(new PyType(builtins.TypeError), value:null, traceback:null, "Type error, the second", innerException:pyArgExc);
+                throw pyerrSecond;
+
+            }
+        }
     }
 
 
diff --git a/tests/test_exceptions.py b/tests/test_exceptions.py
@@ -8,6 +8,51 @@
 import pytest
 import pickle
 
+# begin code from https://utcc.utoronto.ca/~cks/space/blog/python/GetAllObjects
+import gc
+# Recursively expand slist's objects
+# into olist, using seen to track
+# already processed objects.
+
+def _getr(slist, olist, seen):
+    for e in slist:
+      if id(e) in seen:
+        continue
+      seen[id(e)] = None
+      olist.append(e)
+      tl = gc.get_referents(e)
+      if tl:
+        _getr(tl, olist, seen)
+
+# The public function.
+def get_all_objects():
+    gcl = gc.get_objects()
+    olist = []
+    seen = {}
+    # Just in case:
+    seen[id(gcl)] = None
+    seen[id(olist)] = None
+    seen[id(seen)] = None
+    # _getr does the real work.
+    _getr(gcl, olist, seen)
+    return olist
+# end code from https://utcc.utoronto.ca/~cks/space/blog/python/GetAllObjects
+
+def leak_check(func):
+    def do_leak_check():
+        func()
+        gc.collect()
+        exc = {x for x in get_all_objects() if isinstance(x, Exception) and not isinstance(x, pytest.PytestDeprecationWarning)}
+        print(len(exc))
+        if len(exc):
+            for x in exc:
+                print('-------')
+                print(repr(x))
+                print(gc.get_referrers(x))
+                print(len(gc.get_referrers(x)))
+            assert False
+    gc.collect()
+    return do_leak_check
 
 def test_unified_exception_semantics():
     """Test unified exception semantics."""
@@ -375,3 +420,33 @@ def test_iteration_innerexception():
     # after exception is thrown iterator is no longer valid
     with pytest.raises(StopIteration):
         next(val)
+
+def leak_test(func):
+    def do_test_leak():
+        # PyTest leaks things, gather the current state
+        orig_exc = {x for x in get_all_objects() if isinstance(x, Exception)}
+        func()
+        exc = {x for x in get_all_objects() if isinstance(x, Exception)}
+        possibly_leaked = exc - orig_exc
+        assert not possibly_leaked
+
+    return do_test_leak
+
+@leak_test
+def test_dont_leak_exceptions_simple():
+    from Python.Test import ExceptionTest
+
+    try:
+        ExceptionTest.DoThrowSimple()
+    except System.ArgumentException:
+        print('type error, as expected')
+
+@leak_test
+def test_dont_leak_exceptions_inner():
+    from Python.Test import ExceptionTest
+    try:
+        ExceptionTest.DoThrowWithInner()
+    except TypeError:
+        print('type error, as expected')
+    except System.ArgumentException:
+        print('type error, also expected')
