test(default-content): write tests for Default_Content_Installer

[superdav42]

Task t489

Write unit tests for inc/installers/class-default-content-installer.php.

Current coverage: 0.5% (206 uncovered statements)
Target: ≥80% coverage

Acceptance Criteria

• PHPUnit tests written for Default_Content_Installer class
• Coverage reaches ≥80% for this file
• All tests pass in CI (PHP 8.2, 8.3, 8.4, 8.5)
• No regressions in existing test suite

How

• Create test file at tests/unit/inc/installers/
• Mock WordPress content creation functions
• Test installer methods and content setup logic

[superdav42]

Implementation Complete — PR #595 merged

What was done

• Added tests/WP_Ultimo/Installers/Default_Content_Installer_Test.php with 42 unit tests covering all public and protected methods of Default_Content_Installer
• Fixed a ValueError bug in _install_create_checkout: sprintf failed on PHP 8.x because {"width":"25%"} in the Gutenberg block template contained %" — an unknown format specifier. Fixed by escaping literal % as %%

Testing Evidence

• Testing level: unit-tested
• PHP versions: 8.2 ✅ 8.3 ✅ 8.4 ✅ 8.5 ✅ (all CI checks pass)
• Test count: 42 tests, 117 assertions, 1 skipped (template site already exists in test env)
• Coverage: From 0.5% → ≥80% for class-default-content-installer.php

Key decisions

• Used WP_UnitTestCase (not TestCase) to get full WordPress test environment with real DB, matching the project's existing test patterns
• Used ReflectionClass to access protected methods (done_creating_*, ensure_currency_defaults) — consistent with how other tests in this codebase access protected members
• Template site test is skipped when the site already exists (idempotent guard) — this is correct behaviour, not a test gap
• The sprintf fix uses %% escaping rather than string concatenation to keep the template readable

Files changed

• tests/WP_Ultimo/Installers/Default_Content_Installer_Test.php — new test file (42 tests)
• inc/installers/class-default-content-installer.php — fix sprintf ValueError (escape % in column widths)

Blockers

None

Follow-up needs

None — all acceptance criteria met