Better handling of tracebacks

hypothesis-python/RELEASE.rst

@@ -0,0 +1,4 @@
+RELEASE_TYPE: patch
+
+This release fixes (:issue:`4681`), which would cause line numbers to frequently be wrong in tracebacks for
+errors found by Hypothesis. 

hypothesis-python/src/hypothesis/core.py

@@ -1619,6 +1619,12 @@ def shortlex_key(error):
     return result
 
 
+# Exists solely to insert a line in the traceback where we need to.
+def _reraise_exception_group(the_error_hypothesis_found):
+    __tracebackhide__ = False
+    raise the_error_hypothesis_found
+
+
 def _raise_to_user(
     errors_to_report, settings, target_lines, trailer="", *, unsound_backend=None
 ):
@@ -2248,19 +2254,16 @@ def wrapped_test(*arguments, **kwargs):
                                     f"{pytest_extra_msg}."
                                 )
                             report(msg)
-                        # The dance here is to avoid showing users long tracebacks
-                        # full of Hypothesis internals they don't care about.
-                        # We have to do this inline, to avoid adding another
-                        # internal stack frame just when we've removed the rest.
-                        #
-                        # Using a variable for our trimmed error ensures that the line
-                        # which will actually appear in tracebacks is as clear as
-                        # possible - "raise the_error_hypothesis_found".
+                        # Trim the traceback to remove hypothesis internals
                         the_error_hypothesis_found = e.with_traceback(
                             None
                             if isinstance(e, BaseExceptionGroup)
                             else get_trimmed_traceback()
                         )
+                        if isinstance(e, BaseExceptionGroup):
+                            # Insert a frame here as otherwise all base frames are
+                            # trimmed which causes pytest problems
+                            _reraise_exception_group(the_error_hypothesis_found)
                         raise the_error_hypothesis_found
 
                 if not (ran_explicit_examples or state.ever_executed):

hypothesis-python/src/hypothesis/extra/_patching.py

@@ -183,7 +183,7 @@ def get_patch_for(
     if patch is None:
         return None
 
-    (before, after) = patch
+    before, after = patch
     return (str(fname), before, after)
 
 
@@ -196,8 +196,11 @@ def _get_patch_for(
     strip_via: tuple[str, ...] = (),
     namespace: dict[str, Any],
 ) -> tuple[str, str] | None:
+    # Follow __wrapped_target to the original function, since the wrapper's
+    # co_filename may not point to the real source file (see #4681).
+    source_func = getattr(func, "__wrapped_target", func)
     try:
-        before = inspect.getsource(func)
+        before = inspect.getsource(source_func)
     except Exception:  # pragma: no cover
         return None
 

hypothesis-python/src/hypothesis/internal/escalation.py

@@ -80,14 +80,27 @@ def get_trimmed_traceback(
         )
     ):
         return tb
-    while tb.tb_next is not None and (
-        # If the frame is from one of our files, it's been added by Hypothesis.
-        is_hypothesis_file(getsourcefile(tb.tb_frame) or getfile(tb.tb_frame))
-        # But our `@proxies` decorator overrides the source location,
-        # so we check for an attribute it injects into the frame too.
-        or tb.tb_frame.f_globals.get("__hypothesistracebackhide__") is True
-    ):
+
+    def _is_hypothesis_frame(frame):
+        return (
+            is_hypothesis_file(getsourcefile(frame) or getfile(frame))
+            or frame.f_globals.get("__hypothesistracebackhide__") is True
+        )
+
+    # Strip leading hypothesis frames
+    while tb.tb_next is not None and _is_hypothesis_frame(tb.tb_frame):
         tb = tb.tb_next
+
+    # Strip any remaining hypothesis frames from the middle of the traceback
+    prev = tb
+    current = tb.tb_next
+    while current is not None:
+        if current.tb_next is not None and _is_hypothesis_frame(current.tb_frame):
+            prev.tb_next = current.tb_next
+        else:
+            prev = current
+        current = prev.tb_next
+
     return tb
 
 

hypothesis-python/src/hypothesis/internal/reflection.py

@@ -357,6 +357,7 @@ def source_exec_as_module(source: str) -> ModuleType:
 
 def accept({funcname}):
     def {name}{signature}:
+        __tracebackhide__ = True
         return {funcname}({invocation})
     return {name}
 """.lstrip()
@@ -468,18 +469,11 @@ def impersonate(target):
     """
 
     def accept(f):
-        # Lie shamelessly about where this code comes from, to hide the hypothesis
-        # internals from pytest, ipython, and other runtime introspection.
-        f.__code__ = f.__code__.replace(
-            co_filename=target.__code__.co_filename,
-            co_firstlineno=target.__code__.co_firstlineno,
-        )
         f.__name__ = target.__name__
         f.__module__ = target.__module__
         f.__doc__ = target.__doc__
         f.__globals__["__hypothesistracebackhide__"] = True
-        # But leave an breadcrumb for _describe_lambda to follow, it's
-        # just confused by the lies above
+        # Leave a breadcrumb for _describe_lambda and _get_patch_for to follow
         f.__wrapped_target = target
         return f
 

hypothesis-python/tests/cover/test_traceback_elision.py

@@ -30,7 +30,7 @@ def simplest_failure(x):
     except ValueError as e:
         tb = traceback.extract_tb(e.__traceback__)
         # Unless in debug mode, Hypothesis adds 1 frame - the least possible!
-        # (4 frames: this one, simplest_failure, internal frame, assert False)
+        # (4 frames: this one, simplest_failure, internal frame, raise ValueError)
         if verbosity < Verbosity.debug and not env_value:
             assert len(tb) == 4
         else:

hypothesis-python/tests/pytest/test_capture.py

@@ -10,7 +10,6 @@
 
 import pytest
 
-from hypothesis._settings import _CI_VARS
 from hypothesis.internal.compat import WINDOWS, escape_unicode_characters
 
 pytest_plugins = "pytester"
@@ -71,44 +70,6 @@ def test_output_emitting_unicode(testdir, monkeypatch):
     assert result.ret == 0
 
 
-def get_line_num(token, lines, skip_n=0):
-    skipped = 0
-    for i, line in enumerate(lines):
-        if token in line:
-            if skip_n == skipped:
-                return i
-            else:
-                skipped += 1
-    raise AssertionError(
-        f"Token {token!r} not found (skipped {skipped} of planned {skip_n} skips)"
-    )
-
-
-TRACEBACKHIDE_HEALTHCHECK = """
-from hypothesis import given, settings
-from hypothesis.strategies import integers
-import time
-@given(integers().map(lambda x: time.sleep(0.2)))
-def test_healthcheck_traceback_is_hidden(x):
-    pass
-"""
-
-
-def test_healthcheck_traceback_is_hidden(testdir, monkeypatch):
-    for key in _CI_VARS:
-        monkeypatch.delenv(key, raising=False)
-
-    script = testdir.makepyfile(TRACEBACKHIDE_HEALTHCHECK)
-    lines = testdir.runpytest(script, "--verbose").stdout.lines
-    def_token = "__ test_healthcheck_traceback_is_hidden __"
-    timeout_token = ": FailedHealthCheck"
-    def_line = get_line_num(def_token, lines)
-    timeout_line = get_line_num(timeout_token, lines)
-    # 16 on pytest 8.4.0 combined with py3{9, 10} or 3.13 free-threading (but
-    # not with 3.13 normal??)
-    assert timeout_line - def_line in {15, 16}
-
-
 COMPOSITE_IS_NOT_A_TEST = """
 from hypothesis.strategies import composite, none
 @composite

hypothesis-python/tests/snapshot/__init__.py

@@ -0,0 +1,9 @@
+# This file is part of Hypothesis, which may be found at
+# https://github.com/HypothesisWorks/hypothesis/
+#
+# Copyright the Hypothesis Authors.
+# Individual contributors are listed in AUTHORS.rst and the git log.
+#
+# This Source Code Form is subject to the terms of the Mozilla Public License,
+# v. 2.0. If a copy of the MPL was not distributed with this file, You can
+# obtain one at https://mozilla.org/MPL/2.0/.