Remaining bare `except:` / swallowed exceptions in tests/ and src/ (Codacy + hidden failures)
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Assessment
- Difficulty
- 5/5
- Estimated time
- Over a week
- Newbie friendliness
- 45/100
- Issue type
- Refactor
- Clarity
- Mostly clear
- Activity status
- Active
- Tech stack
- python
- Domain
- computer-vision, devtools, testing-qa
Research direction
Start with #114's PR description and the listed files: tests/test_camera.py, tests/base/test_base_color.py, tests/test_ros.py, tests/conftest.py, and the named src locations. Run each protected test snippet on OpenCV 4 and 5, then review the exception sites and mutation-check that tests fail when behavior is broken. Done means the findings are addressed in focused PRs, the color.py message has a test, and Ruff rules E722, BLE001, and S110 can be enabled.
Written by the indexing model from the issue text.
Description
Follow-up to #51 / #114, which fixed the bare except: pass pattern in tests/test_image_point_features.py. Inventory of what remains as of 2026-10-03 (main at 770a031a). These are likely contributing to the Codacy B grade (Pylint/Pyflakes bare-except and try/except/pass/W0702/W0703-type findings, see #41) and, in tests, hide real failures.
Why it matters
In tests, a bare except: also swallows the AssertionError from assert*, so the test can never fail. Fixing the same pattern in #114 showed that several of those tests had been calling APIs that don't exist (Image.SURF, corners, getpixel, concat), so expect similar findings here: fix by running each snippet unprotected on OpenCV 4 and 5, rewriting against the real API with direct assertions, and mutation-checking that the test now fails when the code is broken (see #114's PR description for the method).
tests/
| File | bare except: |
except Exception + pass/continue |
|---|---|---|
tests/test_camera.py |
11 | 8 |
tests/base/test_base_color.py |
3 | 1 |
tests/test_ros.py |
0 | 3 |
tests/conftest.py |
0 | 2 (probably legitimate GUI-suppression; review rather than blanket-remove) |
src/
| Location | Issue | Suggested fix |
|---|---|---|
base/color.py:966 and :976 (rgb2xyz-style white/primaries lookup) |
bare except: around a dict lookup, then raise ValueError("unknown white value, must be one of" ", ".join(...)). Real bug: the two adjacent string literals concatenate first, so ", ".join(...) uses the whole sentence as the separator; the error message is garbled. |
except KeyError: and build the message with an f-string: f"unknown white value, must be one of {', '.join(_whites)}", plus a test that checks the message |
base/findpeaks.py:119 |
bare except: around Polynomial.fit, then print + continue |
catch the specific exceptions Polynomial.fit raises for a neighbourhood falling off the data; use warnings.warn rather than print |
base/imageio.py:1033 (set_window_title) |
bare except: pass |
except (AttributeError, RuntimeError): (backends without a window manager) |
Camera.py, ImageProcessing.py, base/imageio.py |
one except Exception: pass/continue each |
review each: narrow the exception type or log |
Suggested approach
Separate small PRs: (1) color.py message bug + test (src, real fix), (2) other src sites, (3) tests/test_camera.py, (4) tests/base/test_base_color.py and the rest. Add E722 (bare except) and BLE001/S110 (try-except-pass) to the ruff rule set once clean so it can't regress (see the typing/lint cluster, #40/#41).
Related: #41, #51, #113
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- Avg merge
- 1h 4m
- Merged PRs (30d)
- 9
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