Drop the message argument from assertArchRule()

An ArchRule cannot be built without because(), and the reason it carries is
already rendered in the failure message, so the argument was a second place
to write the same sentence and a chance for the two to drift apart.

PHPUnit's message convention earns its keep on assertTrue() and friends,
which have no domain context to report. This constraint has plenty, and with
one rule per test method the test name identifies the assertion already.
Callers who really need to prepend something can use assertThat() with the
constraint, which is the right level for an escape hatch.

The test that covered the argument now asserts what replaces it: that the
reason passed to because() reaches the failure message.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FE8ESEV7TzGLDwJuTfdq95

Author: claude

README.md

@@ -47,10 +47,11 @@ final class ArchitectureTest extends TestCase
 }
 ```
 
-That is the whole API: `assertArchRule(ArchRule $rule, ClassSet $classSet, string $message = '')`.
-One rule per test method reads best — PHPUnit names the broken rule and still reports the ones that
-pass. `ArchRuleAsserts` is a trait rather than a base test case so it also works when the parent
-class is already taken, by `KernelTestCase` or your own.
+That is the whole API: `assertArchRule(ArchRule $rule, ClassSet $classSet)`. There is no message
+argument, because a rule cannot be built without `because()` — the reason is already in the failure
+output. One rule per test method reads best: PHPUnit names the broken rule and still reports the
+ones that pass. `ArchRuleAsserts` is a trait rather than a base test case so it also works when the
+parent class is already taken, by `KernelTestCase` or your own.
 
 ## Writing rules
 

src/ArchRuleAsserts.php

@@ -19,9 +19,13 @@ trait ArchRuleAsserts
 {
     /**
      * Asserts that every class in $classSet satisfies $rule.
+     *
+     * There is deliberately no $message argument: an ArchRule cannot be built without
+     * because(), so the reason is already part of the failure message. Anyone who really
+     * needs to prepend something can call assertThat() with the constraint directly.
      */
-    public static function assertArchRule(ArchRule $rule, ClassSet $classSet, string $message = ''): void
+    public static function assertArchRule(ArchRule $rule, ClassSet $classSet): void
     {
-        Assert::assertThat($rule, new ArchRuleCheckerConstraintAdapter($classSet), $message);
+        Assert::assertThat($rule, new ArchRuleCheckerConstraintAdapter($classSet));
     }
 }

tests/ArchRuleAssertsTest.php

@@ -31,12 +31,12 @@ public function test_it_fails_on_a_violated_rule(): void
         self::assertArchRule(self::violatedRule(), self::mvcClassSet());
     }
 
-    public function test_it_prepends_the_custom_message_to_the_failure(): void
+    public function test_it_reports_the_reason_given_to_because(): void
     {
         $this->expectException(ExpectationFailedException::class);
-        $this->expectExceptionMessage('controllers must be container aware');
+        $this->expectExceptionMessage('because i said so');
 
-        self::assertArchRule(self::violatedRule(), self::mvcClassSet(), 'controllers must be container aware');
+        self::assertArchRule(self::violatedRule(), self::mvcClassSet());
     }
 
     private static function mvcClassSet(): ClassSet