Add comprehensive test suite with example rule

- Create RuleTestCaseTest to validate RuleTestCase functionality
- Add DisallowDivisionByLiteralZeroRule as example PHPStan rule
- Implement proper PSR-4 namespace structure for tests
- Organize test data in Data directory following convention
- Include test data file with expected error comments

The test suite demonstrates how to use RuleTestCase and validates
that the enhanced testing framework works correctly with error
detection and validation.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

Author: JanTvrdik

tests/Rule/Data/DisallowDivisionByLiteralZeroRule/DisallowDivisionByLiteralZeroRule.php

@@ -0,0 +1,36 @@
+<?php declare(strict_types = 1);
+
+namespace ShipMonkTests\PHPStanDev\Rule\Data\DisallowDivisionByLiteralZeroRule;
+
+use PhpParser\Node;
+use PhpParser\Node\Expr\BinaryOp\Div;
+use PhpParser\Node\Scalar\Int_;
+use PHPStan\Analyser\Scope;
+use PHPStan\Rules\Rule;
+use PHPStan\Rules\RuleErrorBuilder;
+
+/**
+ * @implements Rule<Div>
+ */
+class DisallowDivisionByLiteralZeroRule implements Rule
+{
+
+    public function getNodeType(): string
+    {
+        return Div::class;
+    }
+
+    public function processNode(Node $node, Scope $scope): array
+    {
+        if ($node->right instanceof Int_ && $node->right->value === 0) {
+            return [
+                RuleErrorBuilder::message('Division by literal zero is not allowed')
+                    ->identifier('shipmonk.divisionByZero')
+                    ->build(),
+            ];
+        }
+
+        return [];
+    }
+
+}

tests/Rule/Data/DisallowDivisionByLiteralZeroRule/code.php

@@ -0,0 +1,16 @@
+<?php declare(strict_types = 1);
+
+namespace DisallowDivisionByLiteralZeroRule;
+
+function testDivision(): void
+{
+    $a = 10;
+    $b = 0;
+
+    $validDivision = $a / 2;
+    $validDivisionWithVariable = $a / $b;
+
+    $invalidDivision = $a / 0; // error: Division by literal zero is not allowed
+    $anotherInvalidDivision = 5 / 0; // error: Division by literal zero is not allowed
+}
+

tests/RuleTestCaseTest.php

@@ -0,0 +1,26 @@
+<?php declare(strict_types = 1);
+
+namespace ShipMonkTests\PHPStanDev;
+
+use PHPStan\Rules\Rule;
+use ShipMonk\PHPStanDev\RuleTestCase;
+use ShipMonkTests\PHPStanDev\Rule\Data\DisallowDivisionByLiteralZeroRule\DisallowDivisionByLiteralZeroRule;
+
+/**
+ * @extends RuleTestCase<DisallowDivisionByLiteralZeroRule>
+ */
+class RuleTestCaseTest extends RuleTestCase
+{
+
+    protected function getRule(): Rule
+    {
+        return new DisallowDivisionByLiteralZeroRule();
+    }
+
+    public function testRule(): void
+    {
+        $this->analyseFile(__DIR__ . '/Rule/Data/DisallowDivisionByLiteralZeroRule/code.php');
+    }
+
+}
+