From b22fabb262fdcb83715d131eece8548d8f93c764 Mon Sep 17 00:00:00 2001
From: Tomas Votruba <tomas.vot@gmail.com>
Date: Sun, 2 Jun 2024 12:00:27 +0900
Subject: [PATCH] Allow abstract classes to be implemented in
 NoSingleInterfaceImplementerRule (#135)

---
 src/Collector/ImplementedInterfaceCollector.php          | 9 +++++++--
 .../Fixture/AllowAbstract.php                            | 9 +++++++++
 .../NoSingleInterfaceImplementerRuleTest.php             | 1 +
 3 files changed, 17 insertions(+), 2 deletions(-)
 create mode 100644 tests/Rules/NoSingleInterfaceImplementerRule/Fixture/AllowAbstract.php

diff --git a/src/Collector/ImplementedInterfaceCollector.php b/src/Collector/ImplementedInterfaceCollector.php
index 5b97a12e..21bfe0f0 100644
--- a/src/Collector/ImplementedInterfaceCollector.php
+++ b/src/Collector/ImplementedInterfaceCollector.php
@@ -18,12 +18,17 @@ public function getNodeType(): string
 
     /**
      * @param Class_ $node
-     * @return string[]
+     * @return string[]|null
      */
-    public function processNode(Node $node, Scope $scope): array
+    public function processNode(Node $node, Scope $scope): ?array
     {
         $implementedInterfaceNames = [];
 
+        // skip abstract classes, as they can enforce child implementations
+        if ($node->isAbstract()) {
+            return null;
+        }
+
         foreach ($node->implements as $implement) {
             $implementedInterfaceNames[] = $implement->toString();
         }
diff --git a/tests/Rules/NoSingleInterfaceImplementerRule/Fixture/AllowAbstract.php b/tests/Rules/NoSingleInterfaceImplementerRule/Fixture/AllowAbstract.php
new file mode 100644
index 00000000..a67c3395
--- /dev/null
+++ b/tests/Rules/NoSingleInterfaceImplementerRule/Fixture/AllowAbstract.php
@@ -0,0 +1,9 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Symplify\PHPStanRules\Tests\Rules\NoSingleInterfaceImplementerRule\Fixture;
+
+abstract class AllowAbstract implements SimpleInterface
+{
+}
diff --git a/tests/Rules/NoSingleInterfaceImplementerRule/NoSingleInterfaceImplementerRuleTest.php b/tests/Rules/NoSingleInterfaceImplementerRule/NoSingleInterfaceImplementerRuleTest.php
index d9ca4389..43e16165 100644
--- a/tests/Rules/NoSingleInterfaceImplementerRule/NoSingleInterfaceImplementerRuleTest.php
+++ b/tests/Rules/NoSingleInterfaceImplementerRule/NoSingleInterfaceImplementerRuleTest.php
@@ -31,6 +31,7 @@ public function testRule(array $filePaths, array $expectedErrorMessagesWithLines
     public static function provideData(): Iterator
     {
         yield [[__DIR__ . '/Fixture/SimpleInterface.php'], []];
+        yield [[__DIR__ . '/Fixture/AllowAbstract.php', __DIR__ . '/Fixture/SimpleInterface.php'], []];
 
         yield [
             [