Start of a test to make sure the profiler/tracer support in the core

interpreter is reporting what we expect to see.

Lib/test/test_profilehooks.py

+import pprint
+import sys
+import unittest
+
+import test_support
+
+
+class HookWatcher:
+    def __init__(self):
+        self.frames = []
+        self.events = []
+
+    def callback(self, frame, event, arg):
+        self.add_event(event, frame)
+
+    def add_event(self, event, frame=None):
+        """Add an event to the log."""
+        if frame is None:
+            frame = sys._getframe(1)
+
+        try:
+            frameno = self.frames.index(frame)
+        except ValueError:
+            frameno = len(self.frames)
+            self.frames.append(frame)
+
+        self.events.append((frameno, event, ident(frame)))
+
+    def get_events(self):
+        """Remove calls to add_event()."""
+        add_event = self.add_event.im_func.func_code
+        disallowed = (add_event.co_firstlineno, add_event.co_name)
+
+        return [item for item in self.events if item[2] != disallowed]
+
+
+class ProfileHookTestCase(unittest.TestCase):
+
+    def check_events(self, callable, expected):
+        events = capture_events(callable)
+        if events != expected:
+            self.fail("Expected events:\n%s\nReceived events:\n%s"
+                      % (pprint.pformat(expected), pprint.pformat(events)))
+
+    def test_simple(self):
+        def f(p):
+            pass
+        f_ident = ident(f)
+        self.check_events(f, [(0, 'call', f_ident),
+                              (0, 'return', f_ident),
+                              ])
+
+    def test_exception(self):
+        def f(p):
+            try:
+                1/0
+            except:
+                pass
+        f_ident = ident(f)
+        self.check_events(f, [(0, 'call', f_ident),
+                              (0, 'exception', f_ident),
+                              (0, 'return', f_ident),
+                              ])
+
+    def test_nested_exception(self):
+        def f(p):
+            1/0
+        def g(p):
+            try:
+                f(p)
+            except:
+                pass
+        f_ident = ident(f)
+        g_ident = ident(g)
+        self.check_events(g, [(0, 'call', g_ident),
+                              (1, 'call', f_ident),
+                              (1, 'exception', f_ident),
+                              # This isn't what I expected:
+                              (0, 'exception', g_ident),
+                              (0, 'return', g_ident),
+                              ])
+
+
+def ident(function):
+    if hasattr(function, "f_code"):
+        code = function.f_code
+    else:
+        code = function.func_code
+    return code.co_firstlineno, code.co_name
+
+
+def capture_events(callable):
+    p = HookWatcher()
+    sys.setprofile(p.callback)
+    callable(p)
+    sys.setprofile(None)
+    return p.get_events()
+
+
+def show_events(callable):
+    import pprint
+    pprint.pprint(capture_events(callable))
+
+
+def test_main():
+    test_support.run_unittest(ProfileHookTestCase)
+
+
+if __name__ == "__main__":
+    test_main()