Tests: add new InstalledPathsOrderTest

This new test class tests that the plugin always registers the installed_paths in the same order.

I have confirmed that the tests would fail on various CI builds without the fix from 126.

Notes:
* This test is about Composer and the plugin, so does not need to be tested against multiple PHPCS versions.

This test class covers the following bug previously reported:
* Dealerdirect/phpcodesniffer-composer-installer issue 125
* Dealerdirect/phpcodesniffer-composer-installer PR 126

tests/IntegrationTest/InstalledPathsOrderTest.php

@@ -0,0 +1,127 @@
+<?php
+
+/**
+ * This file is part of the Dealerdirect PHP_CodeSniffer Standards
+ * Composer Installer Plugin package.
+ *
+ * @copyright 2022 PHPCodeSniffer Composer Installer Contributors
+ * @license MIT
+ */
+
+namespace Dealerdirect\Composer\Plugin\Installers\PHPCodeSniffer\Tests\IntegrationTest;
+
+use Dealerdirect\Composer\Plugin\Installers\PHPCodeSniffer\Plugin;
+use Dealerdirect\Composer\Plugin\Installers\PHPCodeSniffer\Tests\TestCase;
+
+/**
+ * Test that the plugin always registers the installed_paths in the same order.
+ *
+ * This test is about Composer and the plugin, so does not need to be tested against multiple PHPCS versions.
+ *
+ * @link https://github.com/PHPCSStandards/composer-installer/issues/125
+ * @link https://github.com/PHPCSStandards/composer-installer/pull/126
+ */
+final class InstalledPathsOrderTest extends TestCase
+{
+    private $composerConfigA = array(
+        'name'              => 'phpcs-composer-installer/sort-order-test',
+        'require-dev'       => array(
+            'phpcs-composer-installer/dummy-subdir'  => '*',
+            'phpcs-composer-installer/multistandard' => '*',
+            'phpcs-composer-installer/dummy-src'     => '*',
+        ),
+        'minimum-stability' => 'dev',
+        'prefer-stable'     => true,
+    );
+
+    private $composerConfigB = array(
+        'name'              => 'phpcs-composer-installer/sort-order-test',
+        'require-dev'       => array(
+            'phpcs-composer-installer/multistandard' => '*',
+            'phpcs-composer-installer/dummy-src'     => '*',
+            'phpcs-composer-installer/dummy-subdir'  => '*',
+        ),
+        'minimum-stability' => 'dev',
+        'prefer-stable'     => true,
+    );
+
+    /**
+     * Set up test environment before each test.
+     */
+    protected function set_up()
+    {
+        $this->createTestEnvironment();
+    }
+
+    /**
+     * Clean up after each test.
+     */
+    protected function tear_down()
+    {
+        $this->removeTestEnvironment();
+    }
+
+    /**
+     * Test that the paths registered through the plugin are always registered in the same (sort) order.
+     *
+     * @return void
+     */
+    public function testInstalledPathsAreAlwaysRegisteredInSameOrder()
+    {
+        /*
+         * 1. Install using ConfigA in the Composer global directory.
+         */
+        $this->writeComposerJsonFile($this->composerConfigA, static::$tempGlobalPath);
+
+        // Make sure the plugin runs.
+        $this->assertExecute(
+            'composer global install -v --no-ansi',
+            0,    // Expected exit code.
+            Plugin::MESSAGE_RUNNING_INSTALLER, // Expected stdout.
+            null, // No stderr expectation.
+            'Failed to install dependencies.'
+        );
+
+        /*
+         * 2. Install using ConfigB in the Composer local directory.
+         */
+        $this->writeComposerJsonFile($this->composerConfigB, static::$tempLocalPath);
+
+        // Make sure the plugin runs.
+        $this->assertExecute(
+            sprintf('composer install -v --no-ansi --working-dir=%s', escapeshellarg(static::$tempLocalPath)),
+            0,    // Expected exit code.
+            Plugin::MESSAGE_RUNNING_INSTALLER, // Expected stdout.
+            null, // No stderr expectation.
+            'Failed to install dependencies.'
+        );
+
+        /*
+         * 3. Retrieve the installed paths from both and compare to ensure the order is the same.
+         */
+        $globalPaths = $this->executeCliCommand('"vendor/bin/phpcs" --config-show', static::$tempGlobalPath);
+        $this->assertSame(0, $globalPaths['exitcode'], 'Exitcode for "phpcs --config-show" did not match 0 (global)');
+
+        $localPaths = $this->executeCliCommand('"vendor/bin/phpcs" --config-show', static::$tempLocalPath);
+        $this->assertSame(0, $localPaths['exitcode'], 'Exitcode for "phpcs --config-show" did not match 0 (local)');
+
+        // Get the installed paths setting from the config.
+        $this->assertSame(
+            1,
+            preg_match('`installed_paths:\s+([^\n\r]+)\s+`', $globalPaths['stdout'], $matchGlobal),
+            'Could not find "installed_paths" in the config-show output (global)'
+        );
+        $this->assertSame(
+            1,
+            preg_match('`installed_paths:\s+([^\n\r]+)\s+`', $localPaths['stdout'], $matchLocal),
+            'Could not find "installed_paths" in the config-show output (local)'
+        );
+
+        // Remove any differences caused by global vs local paths and absolute vs relative paths.
+        $matchGlobal = str_replace(array(static::$tempGlobalPath . '/vendor', '../..'), '', $matchGlobal[1]);
+        $matchLocal  = str_replace(array(static::$tempLocalPath . '/vendor', '../..'), '', $matchLocal[1]);
+
+        // Verify that the paths are registered in the same order both times.
+        $this->assertSame($matchGlobal, $matchLocal, 'Order of paths in "installed_paths" is not the same');
+    }
+}