Tests: run against the *new* PHPCS 4 branch

The PHP_CodeSniffer 4.0 branch has been completely rebuild. See PHPCSStandards/PHP_CodeSniffer#120 for more detailed information about the "why".

In practice, this means that to test against the upcoming PHPCS 4.0 release, we need to test against the `4.x` branch now, not the old `4.0` branch.

A 4.0 beta/RC release is expected in the next few days. Once that is out, a test period starts and depending on whether problems are found or not, the 4.0.0 release will be tagged about a month later (or later if significant problems were found).

When 4.0.0 gets tagged, the PHPCS `master` branch will be renamed to `3.x` and the `4.x` branch will be the new "main" branch for PHPCS, so more changes will be needed, but that's for later.

Includes updating to the `DemoSniff` test fixture setup as PHPCS 4.0 will start enforcing for sniffs to implement the `Sniff` interface.

Author: jrfnl

tests/PHPCSVersions.php

@@ -27,7 +27,7 @@ final class PHPCSVersions
      *
      * @var string
      */
-    const NEXT_MAJOR = '4.0.x-dev as 3.9.99';
+    const NEXT_MAJOR = '4.x-dev as 3.9.99';
 
     /**
      * List of all PHPCS version which are supported by this plugin.

tests/fixtures/dummy-subdir/DummySubDir/Sniffs/Demo/DemoSniff.php

@@ -10,6 +10,8 @@
 
 namespace DummySubDir\Sniffs\Demo;
 
+use PHP_CodeSniffer_Sniff as PHPCS_Sniff;
+
 /**
  * Dummy sniff which can be used to verify that PHPCS runs with an external standard.
  *
@@ -18,7 +20,7 @@
  * This is to allow the sniff to be compatible with both PHPCS 2.x as well as 3.x
  * without too much other work-arounds being needed.
  */
-class DemoSniff
+class DemoSniff implements PHPCS_Sniff
 {
     /**
      * Registers the tokens that this sniff wants to listen for.

tests/fixtures/dummy-subdir/DummySubDir/dummy-autoload.php

@@ -0,0 +1,24 @@
+<?php
+/**
+ * PHPCS 2.x Had the `PHP_CodeSniffer_Sniff` interface...
+ * PHPCS 3.x ... renamed that to `PHP_CodeSniffer\Sniffs\Sniff` and ...
+ * PHPCS 4.x ... demands that sniffs implement the interface.
+ *
+ * Additionally, the Ruleset `<autoload>` directive is only supported as of PHPCS 3.0.
+ *
+ * So... for a test fixture "sniff" to be cross-version compatible:
+ * - it must implement the `Sniff` interface for PHPCS 4 compatibility.
+ * - which will need to be class aliased for PHPCS 2 vs 3 compatibility.
+ *
+ * That's what's being done here.
+ *
+ * And we need to alias to the PHPCS 2.x name as only 3.x can include this autoload file using `<autoload>`.
+ */
+
+if ( ! defined( 'PHPCS_ALIASES_SET' ) ) {
+    if ( ! class_exists( '\PHP_CodeSniffer_Sniff' ) ) {
+        class_alias( 'PHP_CodeSniffer\Sniffs\Sniff', '\PHP_CodeSniffer_Sniff' );
+    }
+
+    define( 'PHPCS_ALIASES_SET', true );
+}

tests/fixtures/dummy-subdir/DummySubDir/ruleset.xml

@@ -2,4 +2,6 @@
 <ruleset xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" name="DummySubDir" xsi:noNamespaceSchemaLocation="https://raw.githubusercontent.com/PHPCSStandards/PHP_CodeSniffer/master/phpcs.xsd">
 
     <description>Dummy PHPCS standard for testing.</description>
+
+    <autoload>/dummy-autoload.php</autoload>
 </ruleset>