#20 Impelement ArrayMerge sniff in foreach

Magento2/Sniffs/Performance/ForeachArrayMergeSniff.php

@@ -0,0 +1,71 @@
+<?php
+/**
+ * Copyright © Magento. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+namespace Magento2\Sniffs\Performance;
+
+use PHP_CodeSniffer\Files\File;
+use PHP_CodeSniffer\Sniffs\Sniff;
+
+/**
+ * Detects array_merge(...) is used in a loop and is a resources greedy construction.
+ */
+class ForeachArrayMergeSniff implements Sniff
+{
+    /**
+     * String representation of warning.
+     *
+     * @var string
+     */
+    protected $warningMessage = 'array_merge(...) is used in a loop and is a resources greedy construction.';
+
+    /**
+     * Warning violation code.
+     *
+     * @var string
+     */
+    protected $warningCode = 'ForeachArrayMerge';
+
+    /**
+     * @var array
+     */
+    protected $foreachCache = [];
+
+    /**
+     * @inheritdoc
+     */
+    public function register()
+    {
+        return [T_FOREACH, T_FOR];
+    }
+
+    /**
+     * @inheritdoc
+     */
+    public function process(File $phpcsFile, $stackPtr)
+    {
+        $tokens = $phpcsFile->getTokens();
+
+        $scopeOpener = $tokens[$stackPtr]['scope_opener'];
+        $scopeCloser = $tokens[$stackPtr]['scope_closer'];
+
+        for ($i = $scopeOpener; $i < $scopeCloser; $i++) {
+            $tag = $tokens[$i];
+            if ($tag['code'] !== T_STRING) {
+                continue;
+            }
+            if ($tag['content'] !== 'array_merge') {
+                continue;
+            }
+
+            $cacheKey = $phpcsFile->getFilename() . $i;
+            if (isset($this->foreachCache[$cacheKey])) {
+                continue;
+            }
+
+            $this->foreachCache[$cacheKey] = '';
+            $phpcsFile->addWarning($this->warningMessage, $i, $this->warningCode);
+        }
+    }
+}

Magento2/Tests/Performance/ForeachArrayMergeUnitTest.inc

@@ -0,0 +1,43 @@
+<?php
+$configurationSources = [
+    0 => 'value',
+    1 => 'value2',
+];
+
+$options = [];
+
+foreach ([] as $collection) {
+    foreach ($configurationSources as $source) {
+        $options = array_merge($options, $source);
+    }
+}
+
+$options = [];
+$itemCount = count($configurationSources);
+for ($i = 0; $i <= $itemCount; $i++) {
+    $source = $options[$itemCount];
+    $options = array_merge($options, $source);
+}
+
+class SelectBuilder
+{
+    private $columns = [];
+
+    public function getColumns()
+    {
+        return $this->columns;
+    }
+
+    public function setColumns(array $columns)
+    {
+        $this->columns = $columns;
+    }
+}
+
+$selectBuilder = new SelectBuilder();
+
+foreach ([] as $collection) {
+    foreach ($configurationSources as $source) {
+        $selectBuilder->setColumns(array_merge($selectBuilder->getColumns(), $source));
+    }
+}

Magento2/Tests/Performance/ForeachArrayMergeUnitTest.php

@@ -0,0 +1,35 @@
+<?php
+/**
+ * Copyright © Magento. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+
+namespace Magento2\Tests\Performance;
+
+use PHP_CodeSniffer\Tests\Standards\AbstractSniffUnitTest;
+
+/**
+ * Class EmptyCheckUnitTest
+ */
+class ForeachArrayMergeUnitTest extends AbstractSniffUnitTest
+{
+    /**
+     * @inheritdoc
+     */
+    public function getErrorList()
+    {
+        return [];
+    }
+
+    /**
+     * @inheritdoc
+     */
+    public function getWarningList()
+    {
+        return [
+            11 => 1,
+            19 => 1,
+            41 => 1
+        ];
+    }
+}

Magento2/ruleset.xml

@@ -235,6 +235,10 @@
         <severity>7</severity>
         <type>warning</type>
     </rule>
+    <rule ref="Magento2.Performance.ForeachArrayMerge">
+        <severity>7</severity>
+        <type>warning</type>
+    </rule>
     <rule ref="Magento2.Strings.StringConcat">
         <severity>7</severity>
         <type>warning</type>