Merge pull request #95 from bmitch/bmitchell-#90

Fixes #90

Author: bmitch

README.md

@@ -89,6 +89,9 @@ Classes must be no more than 200 lines.
 ### Codor.Classes.ConstructorLoop ###
 Class constructors must not contain any loops.
 
+### Codor.Classes.Extends ###
+Warns if a class extends another class. Goal is to promote composition over inheritance.
+
 ### Codor.Classes.FinalPrivate ###
 Final classes should not contain protected methods or variables. Should use private instead.
 

src/Codor/Sniffs/Classes/ExtendsSniff.php

@@ -0,0 +1,55 @@
+<?php declare(strict_types = 1);
+
+namespace Codor\Sniffs\Classes;
+
+use PHP_CodeSniffer_Sniff;
+use PHP_CodeSniffer_File;
+
+class ExtendsSniff implements PHP_CodeSniffer_Sniff
+{
+    /**
+     * The file where the token was found.
+     * @var PHP_CodeSniffer_File
+     */
+    private $phpcsFile;
+
+    /**
+     * Returns the token types that this sniff is interested in.
+     * @return array
+     */
+    public function register(): array
+    {
+        return [T_CLASS];
+    }
+
+    /**
+     * Processes the tokens that this sniff is interested in.
+     *
+     * @param PHP_CodeSniffer_File $phpcsFile The file where the token was found.
+     * @param int                  $stackPtr  The position in the stack where
+     *                                        the token was found.
+     * @return void
+     * @SuppressWarnings(PHPMD.UnusedFormalParameter)
+     */
+    public function process(PHP_CodeSniffer_File $phpcsFile, $stackPtr)
+    {
+        $this->phpcsFile = $phpcsFile;
+        foreach ($phpcsFile->getTokens() as $token) {
+            $this->handleToken($token);
+        }
+    }
+
+    /**
+     * Handle the incoming token.
+     * @param  array $token Token data.
+     * @return void
+     */
+    protected function handleToken($token)
+    {
+        if ($token['type'] !== 'T_EXTENDS') {
+            return;
+        }
+        $warning = "Class extends another class - consider composition over inheritance.";
+        $this->phpcsFile->addWarning($warning, $token['line']);
+    }
+}

tests/Sniffs/Classes/Assets/ExtendsSniff/ClassThatDoesNotExtend.inc

@@ -0,0 +1,9 @@
+<?php
+
+class Foobar
+{
+    public function __construct($baz)
+    {
+        $this->baz = $baz
+    }
+}

tests/Sniffs/Classes/Assets/ExtendsSniff/ClassThatExtendsAnotherClass.inc

@@ -0,0 +1,9 @@
+<?php
+
+class Foobar extends Baz
+{
+    public function __construct($baz)
+    {
+        $this->baz = $baz
+    }
+}

tests/Sniffs/Classes/ExtendsSniffTest.php

@@ -0,0 +1,39 @@
+<?php declare(strict_types = 1);
+
+namespace Codor\Tests\Sniffs\Classes;
+
+use Codor\Tests\BaseTestCase;
+
+/** @group Classes */
+class ExtendsSniffTest extends BaseTestCase
+{
+    public function setup()
+    {
+        parent::setup();
+        $this->runner->setSniff('Codor.Classes.Extends')->setFolder(__DIR__.'/Assets/ExtendsSniff/');
+    }
+
+    /** @test */
+    public function a_class_that_does_not_extend_does_not_throw_a_warning()
+    {
+        $results = $this->runner->sniff('ClassThatDoesNotExtend.inc');
+        $this->assertSame(0, $results->getErrorCount());
+        $this->assertSame(0, $results->getWarningCount());
+
+        $errorMessages = $results->getAllErrorMessages();
+        $this->assertCount(0, $errorMessages);
+    }
+
+    /** @test */
+    public function a_class_that_extends_another_throws_a_warning()
+    {
+        $results = $this->runner->sniff('ClassThatExtendsAnotherClass.inc');
+        $this->assertSame(0, $results->getErrorCount());
+        $this->assertSame(1, $results->getWarningCount());
+
+        $warningMessages = $results->getAllWarningMessages();
+        $this->assertCount(1, $warningMessages);
+        $this->assertSame('Class extends another class - consider composition over inheritance.', $warningMessages[0]);
+    }
+
+}