ENH: Convert 8 ImageIntensity tests to GoogleTest

[hjmjohnson]

Mechanical conversion of 8 no-argument legacy CTests in Modules/Filtering/ImageIntensity/test/ to GoogleTest, per the convert-to-gtest skill workflow ("one commit, one change" — N-Dekker).

Test	Commit
itkRoundImageFilterTest	e4b9ee6e
itkSquareImageFilterTest	396bcad6
itkLessTest	afa3f1fb
itkNotEqualTest	79a6e66f
itkGreaterTest	0ebef44a
itkGreaterEqualTest	f200baee
itkLessEqualTest	b82d4b86
itkEqualTest	d678cf4b

Each conversion is a single commit with git mv rename (81-83% similarity, history preserved through git log --follow), ITK_EXERCISE_BASIC_OBJECT_METHODS → ITK_GTEST_EXERCISE_BASIC_OBJECT_METHODS, ITK_TRY_EXPECT_NO_EXCEPTION → ASSERT_NO_THROW, and return-on-failure → ASSERT_EQ(..., EXIT_SUCCESS). No logic refactoring, no comment removal, no spurious [[maybe_unused]].

Verification

• All 8 GTests build and pass locally (each <1ms)
• pre-commit run --all-files exit 0 on the final tip
• CMakeLists alphabetic ordering preserved on both ITKImageIntensityTests (legacy) and ITKImageIntensityGTests sets
• The Equal conversion preserves its Bogus helper class and the 4th sub-block (BinaryFunctorImageFilter instantiation check); all other 7 follow the standard 3-step image-on-image / image-on-constant / constant-on-image pattern

Net: +111 / -267 (conversions are leaner than the originals because the if (status == EXIT_FAILURE) { return EXIT_FAILURE; std::cout << "Step N passed" << std::endl; } boilerplate collapses to a single ASSERT_EQ).

[greptile-apps]

Greptile Summary

Mechanical conversion of 8 no-argument legacy CTests in Modules/Filtering/ImageIntensity/test/ to GoogleTest, following the project's convert-to-gtest workflow. Each file is renamed (itkFooTest.cxx → itkFooGTest.cxx), the legacy entrypoint is replaced with a TEST(Foo, ConvertedLegacyTest) body, itkTestingMacros.h macros are swapped for their GTest equivalents, and the corresponding itk_add_test() / source-list entries are removed from CMakeLists.txt.

All 8 test suite names are unique, all ITK_EXERCISE_BASIC_OBJECT_METHODS → ITK_GTEST_EXERCISE_BASIC_OBJECT_METHODS substitutions are correct, itkTestingMacros.h is removed where it is no longer used, and the GTest source list in CMakeLists.txt is in alphabetical order. The conversion is clean and consistent with project conventions.

Confidence Score: 5/5

This PR is safe to merge — it is a correct mechanical test conversion with no logic changes.

All 8 conversions follow the established convert-to-gtest workflow exactly: unique suite names, correct macro substitutions, itkTestingMacros.h removed where unused, ASSERT_NO_THROW/ASSERT_EQ/EXPECT_EQ used with appropriate fatality semantics, and CMakeLists.txt updated consistently. Pre-commit hooks (including clang-format) passed on the final tip. No logic, no API, and no public interface changes.

No files require special attention.

Important Files Changed

Filename	Overview
Modules/Filtering/ImageIntensity/test/CMakeLists.txt	Removes 8 legacy source entries and their itk_add_test() blocks; adds the 8 new *GTest.cxx files to the GTest driver in alphabetical order.
Modules/Filtering/ImageIntensity/test/itkEqualGTest.cxx	Correct conversion: unique suite name EqualImageFilter, itkGTest.h added, ASSERT_FALSE(filter.IsNull()) replaces null-check returns, ASSERT_EQ(..., EXIT_SUCCESS) replaces status-check pattern; Bogus helper class and 4th sub-block preserved.
Modules/Filtering/ImageIntensity/test/itkRoundImageFilterGTest.cxx	Correct conversion: itkTestingMacros.h removed, ITK_GTEST_EXERCISE_BASIC_OBJECT_METHODS used, ASSERT_NO_THROW wraps Update(), non-fatal EXPECT_EQ used inside iteration loop matching original semantics.
Modules/Filtering/ImageIntensity/test/itkSquareImageFilterGTest.cxx	Correct conversion: itkTestingMacros.h removed, ITK_GTEST_EXERCISE_BASIC_OBJECT_METHODS substituted, diagnostic std::cout and std::cerr output collapsed into EXPECT_TRUE(...) << streaming message.
Modules/Filtering/ImageIntensity/test/itkGreaterEqualGTest.cxx	Clean three-step conversion with unique suite name GreaterEqualImageFilter; pre-existing stale comment '3 != Im2' preserved as-is (not introduced by this PR).
Modules/Filtering/ImageIntensity/test/itkGreaterGTest.cxx	Clean three-step conversion with unique suite name GreaterImageFilter.
Modules/Filtering/ImageIntensity/test/itkLessEqualGTest.cxx	Clean three-step conversion with unique suite name LessEqualImageFilter.
Modules/Filtering/ImageIntensity/test/itkLessGTest.cxx	Clean three-step conversion with unique suite name LessImageFilter.
Modules/Filtering/ImageIntensity/test/itkNotEqualGTest.cxx	Clean three-step conversion with unique suite name NotEqualImageFilter.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[Legacy itkFooTest.cxx\nint main returns EXIT_FAILURE/SUCCESS] -->|git mv + mechanical edit| B[New itkFooGTest.cxx\nTEST suite void body]

    B --> C1[Remove itkTestingMacros.h\nwhere no longer needed]
    B --> C2[ITK_EXERCISE_BASIC_OBJECT_METHODS\n→ ITK_GTEST_EXERCISE_BASIC_OBJECT_METHODS]
    B --> C3[ITK_TRY_EXPECT_NO_EXCEPTION\n→ ASSERT_NO_THROW]
    B --> C4[checkXxxRes + return EXIT_FAILURE\n→ ASSERT_EQ result EXIT_SUCCESS]
    B --> C5[Add #include itkGTest.h]

    D[CMakeLists.txt] --> D1[Remove from ITKImageIntensityTests\nsource list]
    D --> D2[Remove itk_add_test block]
    D --> D3[Add to ITKImageIntensityGTests\nsource list alphabetically]

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_{Reviews (1): Last reviewed commit: "ENH: Convert itkEqualTest to itkEqualGTe..." | Re-trigger Greptile}