Merge pull request #3145 from jakkdl/raisesgroup_fail_reason

Add reason for failed match to RaisesGroup

docs/source/reference-testing.rst

@@ -231,8 +231,12 @@ ExceptionGroup helpers
 .. autoclass:: RaisesGroup
    :members:
 
+   .. autoattribute:: fail_reason
+
 .. autoclass:: Matcher
    :members:
 
+   .. autoattribute:: fail_reason
+
 .. autoclass:: trio.testing._raises_group._ExceptionInfo
    :members:

newsfragments/3145.feature.rst

@@ -0,0 +1 @@
+If `trio.testing.RaisesGroup` does not get the expected exceptions it now raises an `AssertionError` with a helpful message, instead of letting the raised exception/group fall through. The raised exception is available in the ``__context__`` of the `AssertionError` and can be seen in the traceback.

src/trio/_core/_run.py

@@ -76,6 +76,7 @@
     PosArgT = TypeVarTuple("PosArgT")
     StatusT = TypeVar("StatusT", default=None)
     StatusT_contra = TypeVar("StatusT_contra", contravariant=True, default=None)
+    BaseExcT = TypeVar("BaseExcT", bound=BaseException)
 else:
     from typing import TypeVar
 
@@ -123,6 +124,21 @@ def _hypothesis_plugin_setup() -> None:  # pragma: no cover
     _ALLOW_DETERMINISTIC_SCHEDULING = True  # type: ignore
     register_random(_r)
 
+    # monkeypatch repr_callable to make repr's way better
+    # requires importing hypothesis (in the test file or in conftest.py)
+    try:
+        from hypothesis.internal.reflection import get_pretty_function_description
+
+        import trio.testing._raises_group
+
+        def repr_callable(fun: Callable[[BaseExcT], bool]) -> str:
+            # add quotes around the signature
+            return repr(get_pretty_function_description(fun))
+
+        trio.testing._raises_group.repr_callable = repr_callable
+    except ImportError:
+        pass
+
 
 def _count_context_run_tb_frames() -> int:
     """Count implementation dependent traceback frames from Context.run()

src/trio/_tests/test_exports.py

@@ -318,8 +318,11 @@ def lookup_symbol(symbol: str) -> dict[str, str]:
         if module_name == "trio.socket" and class_name in dir(stdlib_socket):
             continue
 
-        # ignore class that does dirty tricks
-        if class_ is trio.testing.RaisesGroup:
+        # Ignore classes that don't use attrs, they only define their members once
+        # __init__ is called (and reason they don't use attrs is because they're going
+        # to be reimplemented in pytest).
+        # Not 100% that's the case, and it works locally, so whatever /shrug
+        if class_ is trio.testing.RaisesGroup or class_ is trio.testing.Matcher:
             continue
 
         # dir() and inspect.getmembers doesn't display properties from the metaclass
@@ -460,11 +463,6 @@ def lookup_symbol(symbol: str) -> dict[str, str]:
                 "send_all_hook",
                 "wait_send_all_might_not_block_hook",
             },
-            trio.testing.Matcher: {
-                "exception_type",
-                "match",
-                "check",
-            },
         }
         if tool == "mypy" and class_ in EXTRAS:
             before = len(extra)