Add sniff that disallows utf8_encode and utf8_decode

These functions can be considered misleading because they only convert
to/from ISO-8859-1, and do not 'magically' detect the source/target
encoding. Using iconv() or mb_convert_encoding() instead makes both
character encodings that play a role in the conversion explicit.

Author: aboks

MoxioSniffs/Sniffs/PHP/DisallowUtf8EncodeDecodeSniff.php

@@ -0,0 +1,25 @@
+<?php
+namespace Moxio\CodeSniffer\MoxioSniffs\Sniffs\PHP;
+
+use Moxio\CodeSniffer\MoxioSniffs\Sniffs\AbstractFunctionCallSniff;
+use PHP_CodeSniffer\Files\File;
+
+class DisallowUtf8EncodeDecodeSniff extends AbstractFunctionCallSniff
+{
+    protected function registerFunctions()
+    {
+        return ['utf8_encode', 'utf8_decode'];
+    }
+
+    protected function processFunctionCall(File $phpcsFile, $functionName, $functionNamePtr, $argumentPtrs)
+    {
+        $error = sprintf('Using %s() is not allowed; use iconv() or mb_convert_encoding() instead', $functionName);
+        $sniffCode = $this->translateFunctionNameToSniffCode($functionName);
+        $phpcsFile->addError($error, $functionNamePtr, $sniffCode);
+    }
+
+    private function translateFunctionNameToSniffCode($functionName)
+    {
+        return implode('', array_map('ucfirst', explode('_', $functionName)));
+    }
+}

MoxioSniffs/Sniffs/Tests/PHP/DisallowUtf8EncodeDecodeSniffTest.inc

@@ -0,0 +1,8 @@
+<?php
+utf8_encode('foo');
+iconv('ISO-8859-1', 'UTF-8', 'foo');
+mb_convert_encoding('foo', 'UTF-8', 'ISO-8859-1');
+
+utf8_decode('foo');
+iconv('UTF-8', 'ISO-8859-1', 'foo');
+mb_convert_encoding('foo', 'ISO-8859-1', 'UTF-8');

MoxioSniffs/Sniffs/Tests/PHP/DisallowUtf8EncodeDecodeSniffTest.php

@@ -0,0 +1,22 @@
+<?php
+namespace Moxio\CodeSniffer\MoxioSniffs\Sniffs\Tests\PHP;
+
+use Moxio\CodeSniffer\MoxioSniffs\Sniffs\PHP\DisallowUtf8EncodeDecodeSniff;
+use Moxio\CodeSniffer\MoxioSniffs\Sniffs\Tests\AbstractSniffTest;
+
+class DisallowUtf8EncodeDecodeSniffTest extends AbstractSniffTest
+{
+    protected function getSniffClass()
+    {
+        return DisallowUtf8EncodeDecodeSniff::class;
+    }
+
+    public function testSniff()
+    {
+        $file = __DIR__ . '/DisallowUtf8EncodeDecodeSniffTest.inc';
+        $this->assertFileHasErrorsOnLines($file, [
+            2,
+            6,
+        ]);
+    }
+}