hrw4u: Add code coverage support for tests

[zwoop]

• Adds some new tests, for additional coverage (e.g. debug runs)
• Eliminates some dead code discovered when there's no way to get the coverage over such code.

[Copilot]

Pull request overview

This PR enhances the HRW4U toolchain’s Python test suite and coverage workflow by adding targeted unit tests (including a debug-mode pass), adding pytest-cov configuration/Makefile targets, and trimming unused helper code in several HRW4U modules.

Changes:

• Add new unit tests for common.py helpers and for LSPPatternMatcher in tables.py, plus a debug-mode regression run over the “examples” test group.
• Add pytest-cov as a dev dependency and wire up make coverage / make coverage-open, plus coverage configuration and ignore rules.
• Remove unused/dead helper methods in several src/ modules to reduce maintenance surface.

Reviewed changes

Copilot reviewed 15 out of 15 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
tools/hrw4u/tests/utils.py	Adds optional debug passthrough to visitor construction for existing golden tests.
tools/hrw4u/tests/test_tables.py	New unit tests covering LSPPatternMatcher pattern classification.
tools/hrw4u/tests/test_debug_mode.py	New tests that re-run the examples group with debug=True for both forward and reverse visitors.
tools/hrw4u/tests/test_common.py	New in-process unit tests for hrw4u.common functions to improve coverage visibility.
tools/hrw4u/src/visitor_base.py	Removes unused centralized error/indent utilities; relies on remaining context managers and trap handling.
tools/hrw4u/src/validation.py	Removes unused validators/imports.
tools/hrw4u/src/symbols_base.py	Removes unused caches/helpers and tightens imports.
tools/hrw4u/src/interning.py	Removes unused intern_any utility.
tools/hrw4u/src/generators.py	Removes unused reverse-map generation helpers, leaving the consolidated reverse map generator.
tools/hrw4u/src/errors.py	Removes unused exception note helpers.
tools/hrw4u/src/debugging.py	Removes unused context-manager methods and import.
tools/hrw4u/src/common.py	Changes create_base_parser()’s input_file argument behavior (now defaults to None).
tools/hrw4u/pyproject.toml	Adds pytest-cov and configures coverage run/report settings.
tools/hrw4u/Makefile	Adds coverage targets and cleans coverage artifacts.
tools/hrw4u/.gitignore	Ignores coverage outputs (htmlcov/, .coverage).

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[Copilot]

Pull request overview

Copilot reviewed 16 out of 16 changed files in this pull request and generated no new comments.

Comments suppressed due to low confidence (1)

tools/hrw4u/tests/test_units.py:33

• sys, os, and SuffixGroup are imported here but not referenced anywhere in this test module. Please remove unused imports to keep the test file clean and avoid failing any future linting checks.

from hrw4u.types import MapParams, VarType, SuffixGroup
import pytest
import sys
import os

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