Generic/LowercasedFilename: improve code coverage (#681)

Includes adding a test for handling STDIN per suggestion during code review.

src/Standards/Generic/Tests/Files/LowercasedFilenameUnitTest.php

@@ -9,6 +9,9 @@
 
 namespace PHP_CodeSniffer\Standards\Generic\Tests\Files;
 
+use PHP_CodeSniffer\Files\DummyFile;
+use PHP_CodeSniffer\Ruleset;
+use PHP_CodeSniffer\Tests\ConfigDouble;
 use PHP_CodeSniffer\Tests\Standards\AbstractSniffUnitTest;
 
 /**
@@ -20,6 +23,24 @@ final class LowercasedFilenameUnitTest extends AbstractSniffUnitTest
 {
 
 
+    /**
+     * Get a list of all test files to check.
+     *
+     * @param string $testFileBase The base path that the unit tests files will have.
+     *
+     * @return string[]
+     */
+    protected function getTestFiles($testFileBase)
+    {
+        $testFileDir = dirname($testFileBase);
+        $testFiles   = parent::getTestFiles($testFileBase);
+        $testFiles[] = $testFileDir.DIRECTORY_SEPARATOR.'lowercased_filename_unit_test.inc';
+
+        return $testFiles;
+
+    }//end getTestFiles()
+
+
     /**
      * Returns the lines where errors should occur.
      *
@@ -58,4 +79,28 @@ public function getWarningList()
     }//end getWarningList()
 
 
+    /**
+     * Test the sniff bails early when handling STDIN.
+     *
+     * @return void
+     */
+    public function testStdIn()
+    {
+        $config            = new ConfigDouble();
+        $config->standards = ['Generic'];
+        $config->sniffs    = ['Generic.Files.LowercasedFilename'];
+
+        $ruleset = new Ruleset($config);
+
+        $content = '<?php ';
+        $file    = new DummyFile($content, $ruleset, $config);
+        $file->process();
+
+        $this->assertSame(0, $file->getErrorCount());
+        $this->assertSame(0, $file->getWarningCount());
+        $this->assertCount(0, $file->getErrors());
+
+    }//end testStdIn()
+
+
 }//end class

src/Standards/Generic/Tests/Files/lowercased_filename_unit_test.inc

@@ -0,0 +1 @@
+<?php