Hide traceback frames with __tracebackhide__ = True.

.pre-commit-config.yaml

@@ -32,7 +32,7 @@ repos:
     -   id: rst-inline-touching-normal
     -   id: text-unicode-replacement-char
 -   repo: https://github.com/asottile/pyupgrade
-    rev: v2.21.0
+    rev: v2.21.2
     hooks:
     -   id: pyupgrade
         args: [--py36-plus]
@@ -45,7 +45,7 @@ repos:
     hooks:
     -   id: setup-cfg-fmt
 -   repo: https://github.com/psf/black
-    rev: 21.6b0
+    rev: 21.7b0
     hooks:
     -   id: black
 -   repo: https://github.com/asottile/blacken-docs

docs/source/changes.rst

@@ -23,6 +23,8 @@ all releases are available on `PyPI <https://pypi.org/project/pytask>`_ and
 - :gh:`121` add skipped and persisted tasks to the execution footer.
 - :gh:`127` make the table during execution the default. Silence pytask with negative
   verbose mode integers and increase verbosity with positive ones.
+- :gh:`129` allows to hide frames from the traceback by using ``__tracebackhide__ =
+  True``.
 
 
 0.0.16 - 2021-06-25

src/_pytask/traceback.py

@@ -27,12 +27,17 @@ def remove_internal_traceback_frames_from_exc_info(exc_info):
     return exc_info
 
 
-def _is_internal_traceback_frame(frame):
-    """Returns ``True`` if traceback frame belongs to internal packages.
+def _is_internal_or_hidden_traceback_frame(frame):
+    """Returns ``True`` if traceback frame belongs to internal packages or is hidden.
 
-    Internal packages are ``_pytask`` and ``pluggy``.
+    Internal packages are ``_pytask`` and ``pluggy``. A hidden frame is indicated by a
+    local variable called ``__tracebackhide__ = True``.
 
     """
+    is_hidden = frame.tb_frame.f_locals.get("__tracebackhide__", False)
+    if is_hidden:
+        return True
+
     path = Path(frame.tb_frame.f_code.co_filename)
     return any(root in path.parents for root in [_PLUGGY_DIRECTORY, _PYTASK_DIRECTORY])
 
@@ -44,7 +49,7 @@ def _filter_internal_traceback_frames(frame):
 
     """
     for frame in _yield_traceback_frames(frame):
-        if frame is None or not _is_internal_traceback_frame(frame):
+        if frame is None or not _is_internal_or_hidden_traceback_frame(frame):
             break
     return frame
 

tests/test_traceback.py

@@ -0,0 +1,26 @@
+import textwrap
+
+import pytest
+from pytask import cli
+
+
+@pytest.mark.parametrize("is_hidden", [True, False])
+def test_hide_traceback_from_error_report(runner, tmp_path, is_hidden):
+    source = f"""
+    def task_main():
+        a = "This variable should not be shown."
+        __tracebackhide__ = {is_hidden}
+
+
+        helper()
+
+
+    def helper():
+        raise Exception
+    """
+    tmp_path.joinpath("task_main.py").write_text(textwrap.dedent(source))
+
+    result = runner.invoke(cli, [tmp_path.as_posix(), "--show-locals"])
+
+    assert result.exit_code == 1
+    assert ("This variable should not be shown." in result.output) is not is_hidden

tox.ini

@@ -68,6 +68,7 @@ ignore =
 max-line-length = 88
 per-file-ignores =
     src/_pytask/hookspecs.py: U100
+    src/_pytask/outcomes.py: N818
     tests/test_capture.py: T000, T001, N802, PT011
 pytest-mark-no-parentheses = true
 warn-symbols =