Simplify tests/helpers/maturin.py: consolidate 12 functions into 2–3 and defer abstraction until second consumer exists

[coderabbitai]

Summary

tests/helpers/maturin.py has grown to 281 lines and 12 functions serving a single consumer (cuprum/unittests/test_maturin_build.py), introduced as part of a maturin version pin update (PR #59). The module introduces speculative abstractions disproportionate to the problem scope, as acknowledged by the existing follow-up issue #97.

Specific concerns

• Pin-reading logic (read_expected_maturin_version, read_maturin_pins, and related helpers) is used only by the three tests in test_maturin_build.py and should be inlined there.
• Wheel snapshot parsing is split across too many single-purpose functions; 2–3 primary functions would cover the required behaviour without the current depth of extraction.
• Several helpers exist purely for speculative platform-variability normalisation that no current test exercises.
• The module should not be abstracted further until a second concrete consumer exists and the shared interface can be designed against real requirements.

Resolution

• Inline pin-reading logic directly into cuprum/unittests/test_maturin_build.py.
• Consolidate wheel snapshot parsing into 2–3 primary functions rather than 12.
• Remove speculative platform-variability normalisation that is unexercised by any current test.
• Defer any re-extraction into a shared helper module until a second concrete consumer exists.

Context

Identified during review of PR #59 (maturin 1.6.0 → 1.13.3 version bump).
Related issue: #97.

Raised by @leynos.

[coderabbitai]

⚠️ Possible Duplicate Issue(s)

• Simplify tests/helpers/maturin.py: inline pin-collection logic and remove speculative abstractions #97

🔗 Related PRs

leynos/axinite#175 - Flatten build tool override resolution (#39) [merged]
leynos/dear-diary#27 - Adopt Cranelift codegen and mold linking [merged]
#59 - Update maturin pin to latest stable (#27) [closed]
leynos/shared-actions#271 - Export the cargo-binstall version pin [merged]
leynos/agent-template-python#12 - Align Python template docs and scripting guidance with cuprum standards [merged]

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