ENH: Convert 12 ITKCommon CTests to GoogleTest framework

[hjmjohnson]

Summary

Converts no-argument CTests in Modules/Core/Common/test/ to GoogleTest,
each in a separate commit. Adds the ITK_GTEST_SET_GET_VALUE macro to
itkGTest.h for use in subsequent conversions.

Converted tests

Old CTest	New GTest file	Key assertions added
itkVersionTest	itkVersionGTest	EXPECT_EQ for major/minor/patch versions
itkDataTypeTest	itkDataTypeGTest	EXPECT_EQ per vector element
itkEventObjectTest	itkEventObjectGTest	EXPECT_TRUE/FALSE for derivation/matching, EXPECT_STREQ for name
itkModifiedTimeTest	itkModifiedTimeGTest	EXPECT_GT/GE for time ordering
itkByteSwapTest	itkByteSwapGTest	EXPECT_EQ per type after double-swap round-trip
itkIntTypesTest	itkIntTypesGTest	EXPECT_TRUE for size/signedness per type group
itkMathRoundTest + itkMathRoundTest2 + itkMathRoundProfileTest1	itkMathRoundGTest	EXPECT_TRUE on templated round/floor/ceil correctness
itkMathCastWithRangeCheckTest	itkMathCastWithRangeCheckGTest	EXPECT_THROW for overflow, EXPECT_TRUE per target type
itkTimeStampTest	itkTimeStampGTest	EXPECT_LE/EXPECT_EQ for thread-safe monotonic timestamps
itkBoundingBoxTest	itkBoundingBoxGTest	EXPECT_EQ/EXPECT_NEAR for bounds, center, diagonal, corners
itkBoundaryConditionTest	itkBoundaryConditionGTest	EXPECT_EQ for all 15 boundary neighborhood pixel values

Approach

• All diagnostic std::cout output preserved
• Expected values determined by running original tests against the build
• Tests split into logical sub-cases within each file
• Old Test.cxx files removed; entries removed from ITKCommon1Tests list and itk_add_test() calls
• New GTest.cxx files added to ITKCommonGTests list

Test plan

• Each GTest file builds without errors
• Each GTest runs and passes (--gtest_filter=<TestSuite>*)
• CMakeLists.txt updated correctly (removed from driver list, added to GTest list)
• Full CI green

🤖 Generated with Claude Code

[hjmjohnson]

FYI: I'm trying to keep up with students use of AI coding tools to better understand how to use them effectively. I'm just starting to use claude-code from the command line, and my first attempt at making this use full was to try the following prompt:

Pre-conditions

• purchase claude-code subscription
• install homebrew claude-code
• copy AGENTS.md to CLAUDE.md
• get to the following prompt

Find git commits that convert a ctest to a google test with removal of files with suffix Test.cxx and addition of file GTest.cxx in the same commit.  Report all the commit hashes that meet this requirement. 

Find ctests  in the Modules/Core/Common/test directory that do not take any command line arguments and convert them to 
 GTest (GoogleTest), one-by-one, with a separate git commit for each test converted.   The converted tests should have a filename suffix of GTest.cxx.   Keep the original code structure as much as possible, do not split the ctest into multiple google tests, even if that would be best practice.  preserve all diagnostic console output, even if it does not produce testable cases.  The diagnostic print statements are required to exercise the code even without testing the values.

Use git commits at 
35ff93ef67384eb6e1403f1f30deebc418c7c033
7d9584d3d4c2310b2077152a15750df417e30203
532b323af33ca59fd044d0bcdf83b6dbb2497283                                                                                                                                                                                                                                                     
 5d3c74e76fc430f2aebbb6305fe44a137724c6b4                                                                                                                                                                                                                        
 1fa3910d47d05ce022650aa862e396761fe8863f
 13e1b701fc2af59e5cc35e863ff093940d4e3700                                                                                                                                                                                                                        
 9b0c475d0183c4b06e6265904deff3bc32f5d6f9                                                                                                                                                                                                                        
 bf21063b980b5f0f7084669fa32f5ba2b5ab04f7                                                                                                                                                                                                                        
 4e424b45a2324df40d8af94b99efaa4d0b431958                                                                                                                                                                                                                        
 d3fd4a19b58a912792b6f2c109080d90de74476a                                                                                                                                                                                                                        
 97aeb448be5c8fd7a8d2fe3584204b7f6874b725                                                                                                                                                                                                                        
 1325efa2c35a10b542fec7d2634e84e3d8472a11                                                                                                                                                                                                                        
  532b323af33ca59fd044d0bcdf83b6dbb2497283                                                                                                                                                                                                                       
  d5c348e7ef75b4a6d5e3ab7b528f11618221a754 
as examples of how to accomplish the conversions.    

I would like you to augment the GoogleTest versions and convert the console-printed statements into test values. You can run the tests from the build directory to determine the correct values.  Additionally, some comments that attribute the purpose or authorship of the tests should be preserved.  Do this for all converted tests since upstream/main.              

[dzenanz]

I will re-visit this PR once it is marked "ready for review".

[thewtex]

copy AGENTS.md to CLAUDE.md

This is not necessary -- Claude Code will read AGENTS.md.

[hjmjohnson]

copy AGENTS.md to CLAUDE.md

This is not necessary -- Claude Code will read AGENTS.md.

I thought so too, but according to google:

Claude Code does not natively support the AGENTS.md standard, preferring CLAUDE.md for project-specific instructions. While other AI tools (Cursor, Copilot) use AGENTS.md, Claude Code ignores this file. To work around this, you can symlink CLAUDE.md to AGENTS.md or instruct CLAUDE.md to read AGENTS.md. 

Workarounds to use AGENTS.md in Claude Code:
Symlink: Create a symbolic link so CLAUDE.md points to AGENTS.md.
Reference: Within CLAUDE.md, explicitly tell Claude to read the AGENTS.md file.
Content Copying: Manually duplicate instructions from AGENTS.md into CLAUDE.md. 

As of early 2026, the lack of native support for AGENTS.md is a known friction point for users switching between different AI tools, as CLAUDE.md remains necessary for specialized instructions.

Of course google could be wrong.