Split API core tests by feature

README.md

@@ -326,6 +326,8 @@ Run the lightweight API core test suite:
 composer test
 ```
 
+The test runner lives in `tests/ApiCoreTest.php`. Shared helpers and fixtures live in `tests/Support` and `tests/Fixtures`, while feature test files live in `tests/Feature`.
+
 ## Release Process
 
 Every pull request must have exactly one version label, for example `v0.6`.

REFACTORING.md

@@ -37,6 +37,7 @@ ShiftPHP is moving toward an API-only modular monolith. View templates, compiled
 - [x] GitHub API workflow with PHP 8.3 checks.
 - [x] PR version label validation.
 - [x] Release workflow using PR summary as release notes.
+- [x] Split API core tests into runner, support, fixtures, and feature files.
 
 ## Modular Monolith Direction
 

docs/index.html

@@ -410,10 +410,12 @@ <h2>Errors</h2>
 
         <section id="testing">
             <h2>Testing</h2>
-            <p>The current lightweight test suite is in <code>tests/ApiCoreTest.php</code>.</p>
+            <p>The current lightweight test runner is <code>tests/ApiCoreTest.php</code>.</p>
 
             <pre><code>composer test</code></pre>
 
+            <p>Shared assertions, request helpers, and emitters live in <code>tests/Support</code>. Test-only controllers, DTOs, middleware, and auth fixtures live in <code>tests/Fixtures</code>. Feature test files live in <code>tests/Feature</code>.</p>
+
             <p>The API workflow also validates Composer configuration, dumps autoload files, lints PHP files, runs the API tests, and verifies the route list command.</p>
         </section>
     </main>