ENH: Add comprehensive tests for itk.Image buffer protocol and lifetime

[hjmjohnson]

Summary

Add three test suites for itk.Image data export with automatic feature
detection, allowing cherry-pick into ITKv5.4.5 and forward compatibility
with PEP 688 buffer protocol support.

Tests for unavailable features are skipped (not failed) with
descriptive messages:

SKIP: PEP 688 __buffer__ tests (__buffer__ not available in this ITK version)
SKIP: np.asarray zero-copy tests (zero-copy np.asarray not available in this ITK version)

Test results (tests only, no production code changes)

Python	itkImageTest	itkImageLifetimeTest	itkImageInteropTest
3.10.20	pass (3 skip)	12 pass, 0 fail, 13 skip	pass
3.11.15	pass (3 skip)	12 pass, 0 fail, 13 skip	pass
3.12.13	pass (3 skip)	12 pass, 0 fail, 13 skip	pass
3.13.12	pass (3 skip)	12 pass, 0 fail, 13 skip	pass
3.14.3	pass (3 skip)	12 pass, 0 fail, 13 skip	pass

Zero failures on all Python versions.

Features detected as absent (correct — no production code in this PR):
__buffer__=False, copy_param=False, zero_copy=False

Feature detection

Tests probe the actual ITK build at runtime:

• hasattr(image, '__buffer__') — PEP 688 buffer export
• hasattr(image, '__array_interface__') — NumPy v3 array interface
• image.__array__(copy=None) — NumPy 2.0 copy parameter
• np.asarray mutation test — zero-copy behavior

Test coverage

itkImageTest.py: __buffer__, memoryview, np.asarray, __array__ copy protocol

itkImageLifetimeTest.py: del image safety on every export path, weak-ref GC,
refcount verification, circular reference detection, RSS memory growth (200x cycles).
All tests run inside a function scope with explicit del + gc.collect().

itkImageInteropTest.py: NumPy (CT/MRI/DWI clinical sizes), PyTorch (optional),
Dask (optional)

Motivation

Prepares the test infrastructure for PR #6026 (PEP 688 buffer protocol).
When #6026's production code is added, all 13 skipped tests will run and
pass (verified: 56 pass, 0 fail, 0 skip on Python 3.12+).

Test plan

• 0 failures on Python 3.10, 3.11, 3.12, 3.13, 3.14
• Features correctly detected as absent without production code
• Cherry-pick safe for ITKv5.4.5

🤖 Generated with Claude Code

[greptile-apps]

Greptile Summary

This PR adds three Python test suites for itk.Image buffer protocol and lifetime safety (itkImageTest.py, itkImageLifetimeTest.py, itkImageInteropTest.py), with runtime feature detection that skips tests gracefully on older ITK builds. All previously flagged issues (unconditional __buffer__() calls, silent skip(), check() vs skip() for RSS unavailability) have been resolved in df27b60.

Confidence Score: 5/5

Safe to merge — test-only PR, zero production code changes, all prior review concerns addressed.

All remaining findings are P2. The macOS RSS measurement concern is a test-reliability issue on one platform that does not affect correctness on Linux CI. No failures reported across Python 3.10–3.14.

Modules/Core/Common/wrapping/test/itkImageLifetimeTest.py — get_rss_bytes() macOS path.

Important Files Changed

Filename	Overview
Modules/Core/Common/wrapping/test/CMakeLists.txt	Registers two new Python tests (itkImageInteropPythonTest, itkImageLifetimePythonTest); straightforward addition, no issues.
Modules/Core/Common/wrapping/test/itkImageTest.py	Updated buffer-protocol test with runtime feature detection (HAS_BUFFER, HAS_ARRAY_COPY_PARAM, HAS_ZEROCOPY); all paths properly guarded and skipped when features absent; no issues found.
Modules/Core/Common/wrapping/test/itkImageInteropTest.py	New NumPy/PyTorch/Dask interop test with feature-guarded __buffer__ calls (fixed from earlier review), printing skip(), and sys.exit(1) on failure; no remaining issues.
Modules/Core/Common/wrapping/test/itkImageLifetimeTest.py	New lifetime/GC/leak test; well-structured with explicit del + gc.collect() per section. get_rss_bytes() on macOS uses ru_maxrss (peak, not current RSS), which can give false-negative leak results when prior test phases already pushed the process peak above the leak-test threshold.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[Script start: feature detection] --> B{HAS_BUFFER?}
    A --> C{HAS_ZEROCOPY?}
    A --> D{HAS_ARRAY_COPY_PARAM?}

    B -- yes --> E[Run __buffer__ / memoryview tests]
    B -- no --> F[skip with message]

    C -- yes --> G[Run np.asarray zero-copy / lifetime tests]
    C -- no --> H[skip with message]

    D -- yes --> I[Run __array__ copy= protocol tests]
    D -- no --> J[skip with message]

    E & G & I --> K[Lifetime / GC / refcount / circular-ref checks]
    K --> L[Section 10: RSS growth leak detection]
    L --> M{get_rss_bytes available?}
    M -- Linux /proc --> N[Accurate current RSS delta]
    M -- macOS ru_maxrss --> O[Peak RSS delta — may miss small leaks]
    M -- unavailable --> P[skip RSS tests]
    N & O & P --> Q{failed > 0?}
    Q -- yes --> R[sys.exit 1]
    Q -- no --> S[All tests passed]

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[hjmjohnson]

@thewtex This might be good to backport to 5.4. If you intend to backport #6026, then I would recommend backporting this as well.