Config: add tests for the --generator= argument

tests/Core/Config/GeneratorArgTest.php

@@ -0,0 +1,76 @@
+<?php
+/**
+ * Tests for the \PHP_CodeSniffer\Config --generator argument.
+ *
+ * @license https://github.com/PHPCSStandards/PHP_CodeSniffer/blob/master/licence.txt BSD Licence
+ */
+
+namespace PHP_CodeSniffer\Tests\Core\Config;
+
+use PHP_CodeSniffer\Tests\ConfigDouble;
+use PHPUnit\Framework\TestCase;
+
+/**
+ * Tests for the \PHP_CodeSniffer\Config --generator argument.
+ *
+ * @covers \PHP_CodeSniffer\Config::processLongArgument
+ */
+final class GeneratorArgTest extends TestCase
+{
+
+
+    /**
+     * Ensure that the generator property is set when the parameter is passed.
+     *
+     * @param string $generatorName Generator name.
+     *
+     * @return       void
+     * @dataProvider dataGeneratorNames
+     */
+    public function testGenerators($generatorName)
+    {
+        $config = new ConfigDouble(["--generator=$generatorName"]);
+
+        $this->assertSame($generatorName, $config->generator);
+
+    }//end testGenerators()
+
+
+    /**
+     * Data provider for testGenerators().
+     *
+     * @return array<int, array<string>>
+     * @see    self::testGenerators()
+     */
+    public static function dataGeneratorNames()
+    {
+        return [
+            ['Text'],
+            ['HTML'],
+            ['Markdown'],
+        ];
+
+    }//end dataGeneratorNames()
+
+
+    /**
+     * Ensure that only the first argument is processed and others are ignored.
+     *
+     * @return void
+     */
+    public function testOnlySetOnce()
+    {
+        $config = new ConfigDouble(
+            [
+                "--generator=Text",
+                "--generator=HTML",
+                "--generator=InvalidGenerator",
+            ]
+        );
+
+        $this->assertSame('Text', $config->generator);
+
+    }//end testOnlySetOnce()
+
+
+}//end class