Add rule to detect duplicated Enum values in the same class (#31)

* Add rule to detect duplicated Enum values in the same class

* Add rules.neon files

Author: jdecool

composer.json

@@ -28,7 +28,8 @@
     "extra": {
         "phpstan": {
             "includes": [
-                "extension.neon"
+                "extension.neon",
+                "rules.neon"
             ]
         }
     }

rules.neon

@@ -0,0 +1,2 @@
+rules:
+    - Timeweb\PHPStan\Rule\NoDuplicateEnumValueRule

src/Rule/NoDuplicateEnumValueRule.php

@@ -0,0 +1,86 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Timeweb\PHPStan\Rule;
+
+use PhpParser\Node;
+use PhpParser\Node\Stmt\Class_;
+use PHPStan\Analyser\Scope;
+use PHPStan\Node\ClassConstantsNode;
+use PHPStan\Rules\Rule;
+use PHPStan\ShouldNotHappenException;
+
+/**
+ * @phpstan-implements Rule<ClassConstantsNode>
+ */
+class NoDuplicateEnumValueRule implements Rule
+{
+    public function getNodeType(): string
+    {
+        return ClassConstantsNode::class;
+    }
+
+    public function processNode(Node $node, Scope $scope): array
+    {
+        if (!$node->getClass() instanceof Class_) {
+            return [];
+        }
+
+        $classReflection = $scope->getClassReflection();
+        if (!$scope->isInClass() || !$classReflection) {
+            throw new ShouldNotHappenException();
+        }
+
+        $duplicatedKeysValue = $this->findDuplicatedKeys($node);
+        if (empty($duplicatedKeysValue)) {
+            return [];
+        }
+
+        return [
+            sprintf(
+                'Enum %s contains duplicated values for %s properties',
+                $classReflection->getName(),
+                implode(', ', $duplicatedKeysValue)
+            ),
+        ];
+    }
+
+    /**
+     * @return string[]
+     */
+    private function findDuplicatedKeys(ClassConstantsNode $node): array
+    {
+        $constants = $this->getNodeConstants($node);
+
+        $duplicatedValues = array_filter(
+            array_count_values($constants),
+            static function ($value) {
+                return $value > 1;
+            }
+        );
+
+        $duplicatedKeys = [];
+        foreach ($duplicatedValues as $value => $count) {
+            $duplicatedKeys = array_merge($duplicatedKeys, array_keys($constants, $value));
+        }
+
+        return array_unique($duplicatedKeys);
+    }
+
+    /**
+     * @return array<string, mixed>
+     */
+    private function getNodeConstants(ClassConstantsNode $node): array
+    {
+        $constants = [];
+        foreach ($node->getConstants() as $constant) {
+            foreach ($constant->consts as $const) {
+                $constantName = $const->name->toString();
+                $constants[$constantName] = $const->value->value ?? null;
+            }
+        }
+
+        return $constants;
+    }
+}

tests/Rule/NoDuplicateEnumValueRuleTest.php

@@ -0,0 +1,30 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Timeweb\Tests\PHPStan\Rule;
+
+use PHPStan\Rules\Rule;
+use PHPStan\Testing\RuleTestCase;
+use Timeweb\PHPStan\Rule\NoDuplicateEnumValueRule;
+
+/**
+ * @coversDefaultClass \Timeweb\PHPStan\Rule\NoDuplicateEnumValueRule
+ */
+class NoDuplicateEnumValueRuleTest extends RuleTestCase
+{
+    protected function getRule(): Rule
+    {
+        return new NoDuplicateEnumValueRule();
+    }
+
+    public function testRule(): void
+    {
+        $this->analyse([__DIR__ . '/data/duplicated-enum-values.php'], [
+            [
+                'Enum DuplicateEumValues\MyEnum contains duplicated values for PROP_1, DUPLICATED properties',
+                7,
+            ],
+        ]);
+    }
+}

tests/Rule/data/duplicated-enum-values.php

@@ -0,0 +1,12 @@
+<?php
+
+namespace DuplicateEumValues;
+
+use MyCLabs\Enum\Enum;
+
+class MyEnum extends Enum
+{
+    public const PROP_1 = 1;
+    protected const PROP_2 = 2;
+    private const DUPLICATED = 1;
+}