Reported crash: clicking "Clean Text" with mojibake.csv (a junk corpus
file that the cleaner ran on but produced zero changes) blew up the
results render with
NameError: name 'show_hidden' is not defined
at the cleaned-preview block. ``show_hidden`` was defined inside
``if result.cells_changed:`` and referenced unconditionally below.
Fix on the page itself: hoist the ``show_hidden = st.toggle(...)``
declaration out of the conditional so it's always in scope for the
downstream cleaned-preview render. One toggle now drives both the
Examples table (which only renders when there are changes) AND the
cleaned preview (which always renders).
Generalized regression net: ``tests/test_junk_corpus_tool_pages.py``.
For nine representative junk files (empty, only_nul, mojibake,
invalid_utf8, utf16_le_no_bom, mismatched_columns, all_nulls,
corrupt_xlsx, single_column) and every Ready/Coming-Soon tool page,
the test:
1. Stashes the junk bytes as the home upload via session_state.
2. Runs the page through AppTest, asserts ``app.exception`` is empty.
3. If the page exposes a deterministic primary-action button label,
clicks it and asserts no exception on the post-click render.
Pages that catch a bad file at read time and short-circuit via
``st.error`` + ``st.stop`` are correctly skipped from the
primary-action half (the button isn't rendered). A genuine crash
shows up as ``app.exception`` carrying a Python traceback — exactly
what the user reported, exactly what we now catch.
162 tests collected, 102 passed, 60 skipped. 4 seconds.
Full suite: 2220 passed, 91 skipped, 35 s.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
