Tests: new ConfigDouble test helper class

The PHP_CodeSniffer native `Config` class contains a number of static properties.
As the value of these static properties will be retained between instantiations of the class, config values set in one test can influence the results for another test, which makes tests unstable.

This commit introduces a test "double" of the `Config` class which prevents this from happening.
In _most_ cases, tests should be using this class instead of the "normal" Config, with the exception of select tests for the Config class itself.

Author: jrfnl

tests/ConfigDouble.php

@@ -0,0 +1,196 @@
+<?php
+/**
+ * Config class for use in the tests.
+ *
+ * The Config class contains a number of static properties.
+ * As the value of these static properties will be retained between instantiations of the class,
+ * config values set in one test can influence the results for another test, which makes tests unstable.
+ *
+ * This class is a "double" of the Config class which prevents this from happening.
+ * In _most_ cases, tests should be using this class instead of the "normal" Config,
+ * with the exception of select tests for the Config class itself.
+ *
+ * @author    Juliette Reinders Folmer <phpcs_nospam@adviesenzo.nl>
+ * @copyright 2024 Juliette Reinders Folmer. All rights reserved.
+ * @license   https://github.com/PHPCSStandards/PHP_CodeSniffer/blob/master/licence.txt BSD Licence
+ */
+
+namespace PHP_CodeSniffer\Tests;
+
+use PHP_CodeSniffer\Config;
+use ReflectionProperty;
+
+final class ConfigDouble extends Config
+{
+
+    /**
+     * Whether or not the setting of a standard should be skipped.
+     *
+     * @var boolean
+     */
+    private $skipSettingStandard = false;
+
+
+    /**
+     * Creates a clean Config object and populates it with command line values.
+     *
+     * @param array<string> $cliArgs                An array of values gathered from CLI args.
+     * @param bool          $skipSettingStandard    Whether to skip setting a standard to prevent
+     *                                              the Config class trying to auto-discover a ruleset file.
+     *                                              Should only be set to `true` for tests which actually test
+     *                                              the ruleset auto-discovery.
+     *                                              Note: there is no need to set this to `true` when a standard
+     *                                              is being passed via the `$cliArgs`. Those settings will always
+     *                                              respected.
+     *                                              Defaults to `false`. Will result in the standard being set
+     *                                              to "PSR1" if not provided via `$cliArgs`.
+     * @param bool          $skipSettingReportWidth Whether to skip setting a report-width to prevent
+     *                                              the Config class trying to auto-discover the screen width.
+     *                                              Should only be set to `true` for tests which actually test
+     *                                              the screen width auto-discovery.
+     *                                              Note: there is no need to set this to `true` when a report-width
+     *                                              is being passed via the `$cliArgs`. Those settings will always
+     *                                              respected.
+     *                                              Defaults to `false`. Will result in the reportWidth being set
+     *                                              to "80" if not provided via `$cliArgs`.
+     *
+     * @return void
+     */
+    public function __construct(array $cliArgs=[], $skipSettingStandard=false, $skipSettingReportWidth=false)
+    {
+        $this->skipSettingStandard = $skipSettingStandard;
+
+        $this->resetSelectProperties();
+        $this->preventReadingCodeSnifferConfFile();
+
+        parent::__construct($cliArgs);
+
+        if ($skipSettingReportWidth !== true) {
+            $this->preventAutoDiscoveryScreenWidth();
+        }
+
+    }//end __construct()
+
+
+    /**
+     * Sets the command line values and optionally prevents a file system search for a custom ruleset.
+     *
+     * @param array<string> $args An array of command line arguments to set.
+     *
+     * @return void
+     */
+    public function setCommandLineValues($args)
+    {
+        parent::setCommandLineValues($args);
+
+        if ($this->skipSettingStandard !== true) {
+            $this->preventSearchingForRuleset();
+        }
+
+    }//end setCommandLineValues()
+
+
+    /**
+     * Reset a few properties on the Config class to their default values.
+     *
+     * @return void
+     */
+    private function resetSelectProperties()
+    {
+        $this->setStaticConfigProperty('overriddenDefaults', []);
+        $this->setStaticConfigProperty('executablePaths', []);
+
+    }//end resetSelectProperties()
+
+
+    /**
+     * Prevent the values in a potentially available user-specific `CodeSniffer.conf` file
+     * from influencing the tests.
+     *
+     * This also prevents some file system calls which can influence the test runtime.
+     *
+     * @return void
+     */
+    private function preventReadingCodeSnifferConfFile()
+    {
+        $this->setStaticConfigProperty('configData', []);
+        $this->setStaticConfigProperty('configDataFile', '');
+
+    }//end preventReadingCodeSnifferConfFile()
+
+
+    /**
+     * Prevent searching for a custom ruleset by setting a standard, but only if the test
+     * being run doesn't set a standard itself.
+     *
+     * This also prevents some file system calls which can influence the test runtime.
+     *
+     * The standard being set is the smallest one available so the ruleset initialization
+     * will be the fastest possible.
+     *
+     * @return void
+     */
+    private function preventSearchingForRuleset()
+    {
+        $overriddenDefaults = $this->getStaticConfigProperty('overriddenDefaults');
+        if (isset($overriddenDefaults['standards']) === false) {
+            $this->standards = ['PSR1'];
+            $overriddenDefaults['standards'] = true;
+        }
+
+        self::setStaticConfigProperty('overriddenDefaults', $overriddenDefaults);
+
+    }//end preventSearchingForRuleset()
+
+
+    /**
+     * Prevent a call to stty to figure out the screen width, but only if the test being run
+     * doesn't set a report width itself.
+     *
+     * @return void
+     */
+    private function preventAutoDiscoveryScreenWidth()
+    {
+        $settings = $this->getSettings();
+        if ($settings['reportWidth'] === 'auto') {
+            $this->reportWidth = self::DEFAULT_REPORT_WIDTH;
+        }
+
+    }//end preventAutoDiscoveryScreenWidth()
+
+
+    /**
+     * Helper function to retrieve the value of a private static property on the Config class.
+     *
+     * @param string $name The name of the property to retrieve.
+     *
+     * @return mixed
+     */
+    private function getStaticConfigProperty($name)
+    {
+        $property = new ReflectionProperty('PHP_CodeSniffer\Config', $name);
+        $property->setAccessible(true);
+        return $property->getValue();
+
+    }//end getStaticConfigProperty()
+
+
+    /**
+     * Helper function to set the value of a private static property on the Config class.
+     *
+     * @param string $name  The name of the property to set.
+     * @param mixed  $value The value to set the property to.
+     *
+     * @return void
+     */
+    private function setStaticConfigProperty($name, $value)
+    {
+        $property = new ReflectionProperty('PHP_CodeSniffer\Config', $name);
+        $property->setAccessible(true);
+        $property->setValue(null, $value);
+        $property->setAccessible(false);
+
+    }//end setStaticConfigProperty()
+
+
+}//end class