UnusedPrivateElementsSniff: fixed false positive for write-only properties

Author: kukulich

SlevomatCodingStandard/Sniffs/Classes/UnusedPrivateElementsSniff.php

@@ -127,7 +127,23 @@ public function process(\PHP_CodeSniffer\Files\File $phpcsFile, $classPointer):
 
 			$possibleAssignTokenPointer = TokenHelper::findNextEffective($phpcsFile, $propertyNameTokenPointer + 1);
 			$possibleAssignToken = $tokens[$possibleAssignTokenPointer];
-			if (in_array($possibleAssignToken['code'], \PHP_CodeSniffer\Util\Tokens::$assignmentTokens, true)) {
+			if (
+				in_array($possibleAssignToken['code'], [
+					T_EQUAL,
+					T_PLUS_EQUAL,
+					T_MINUS_EQUAL,
+					T_MUL_EQUAL,
+					T_DIV_EQUAL,
+					T_POW_EQUAL,
+					T_MOD_EQUAL,
+					T_AND_EQUAL,
+					T_OR_EQUAL,
+					T_XOR_EQUAL,
+					T_SL_EQUAL,
+					T_SR_EQUAL,
+					T_CONCAT_EQUAL,
+				], true)
+			) {
 				$writeOnlyProperties[$propertyName] = $propertyNameTokenPointer;
 				return;
 			}

tests/Sniffs/Classes/UnusedPrivateElementsSniffTest.php

@@ -99,6 +99,8 @@ public function testErrors(): void
 			UnusedPrivateElementsSniff::CODE_UNUSED_PROPERTY,
 			'Class ClassWithSomeUnusedProperties contains unused property $unusedStaticProperty2.'
 		);
+
+		$this->assertNoSniffError($resultFile, 123);
 	}
 
 	public function testOnlyPublicElements(): void

tests/Sniffs/Classes/data/classWithSomeUnusedElements.php

@@ -120,4 +120,11 @@ public function methodCalledUsedPrivateMethodWithIncorrectCase()
 	private static $unusedStaticProperty1;
 	static private $unusedStaticProperty2;
 
+	private $propertyUsedAsArrayKey;
+
+	public function propertyUsedAsArrayKey()
+	{
+		return [$this->propertyUsedAsArrayKey => true];
+	}
+
 }