Generic/Syntax: add support for inspecting code passed via STDIN

This commit improves the Generic.PHP.Syntax sniff to make it work when
code is passed via STDIN. Before, any code passed this way would cause a
false negative as the sniff was not taking into account that
`$phpcsFile->getFilename()` might return `STDIN` instead of an actual
file name.

Author: rodrigoprimo

src/Standards/Generic/Sniffs/PHP/SyntaxSniff.php

@@ -56,10 +56,9 @@ public function process(File $phpcsFile, $stackPtr)
             $this->phpPath = Config::getExecutablePath('php');
         }
 
-        $fileName = escapeshellarg($phpcsFile->getFilename());
-        $cmd      = Common::escapeshellcmd($this->phpPath)." -l -d display_errors=1 -d error_prepend_string='' $fileName 2>&1";
-        $output   = shell_exec($cmd);
-        $matches  = [];
+        $cmd     = $this->getPhpLintCommand($phpcsFile);
+        $output  = shell_exec($cmd);
+        $matches = [];
         if (preg_match('/^.*error:(.*) in .* on line ([0-9]+)/m', trim($output), $matches) === 1) {
             $error = trim($matches[1]);
             $line  = (int) $matches[2];
@@ -72,4 +71,25 @@ public function process(File $phpcsFile, $stackPtr)
     }//end process()
 
 
+    /**
+     * Returns the command used to lint PHP code. Uses a different command when the content is
+     * provided via STDIN.
+     *
+     * @param \PHP_CodeSniffer\Files\File $phpcsFile The File object.
+     *
+     * @return string The command used to lint PHP code.
+     */
+    private function getPhpLintCommand(File $phpcsFile)
+    {
+        if ($phpcsFile->getFilename() === 'STDIN') {
+            $content = $phpcsFile->getTokensAsString(0, $phpcsFile->numTokens);
+            return "echo ".escapeshellarg($content)." | ".Common::escapeshellcmd($this->phpPath)." -l -d display_errors=1 -d error_prepend_string='' 2>&1";
+        }
+
+        $fileName = escapeshellarg($phpcsFile->getFilename());
+        return Common::escapeshellcmd($this->phpPath)." -l -d display_errors=1 -d error_prepend_string='' $fileName 2>&1";
+
+    }//end getPhpLintCommand()
+
+
 }//end class

src/Standards/Generic/Tests/PHP/SyntaxUnitTest.php

@@ -10,6 +10,9 @@
 
 namespace PHP_CodeSniffer\Standards\Generic\Tests\PHP;
 
+use PHP_CodeSniffer\Files\DummyFile;
+use PHP_CodeSniffer\Ruleset;
+use PHP_CodeSniffer\Tests\ConfigDouble;
 use PHP_CodeSniffer\Tests\Standards\AbstractSniffUnitTest;
 
 /**
@@ -60,4 +63,105 @@ public function getWarningList()
     }//end getWarningList()
 
 
+    /**
+     * Test the sniff checks syntax when file contents are passed via STDIN.
+     *
+     * @param string $content        The content to test.
+     * @param int    $errorCount     The expected number of errors.
+     * @param array  $expectedErrors The expected errors.
+     *
+     * @dataProvider dataStdIn
+     *
+     * @return void
+     */
+    public function testStdIn($content, $errorCount, $expectedErrors)
+    {
+        $config            = new ConfigDouble();
+        $config->standards = ['Generic'];
+        $config->sniffs    = ['Generic.PHP.Syntax'];
+
+        $ruleset = new Ruleset($config);
+
+        $file = new DummyFile($content, $ruleset, $config);
+        $file->process();
+
+        $this->assertSame(
+            $errorCount,
+            $file->getErrorCount(),
+            'Error count does not match expected value'
+        );
+        $this->assertSame(
+            0,
+            $file->getWarningCount(),
+            'Warning count does not match expected value'
+        );
+        $this->assertSame(
+            $expectedErrors,
+            $file->getErrors(),
+            'Error list does not match expected errors'
+        );
+
+    }//end testStdIn()
+
+
+    /**
+     * Data provider for testStdIn().
+     *
+     * @return array[]
+     */
+    public function dataStdIn()
+    {
+        // The error message changed in PHP 8+.
+        if (PHP_VERSION_ID >= 80000) {
+            $errorMessage = 'PHP syntax error: syntax error, unexpected token ";", expecting "]"';
+        } else {
+            $errorMessage = 'PHP syntax error: syntax error, unexpected \';\', expecting \']\'';
+        }
+
+        return [
+            'No syntax errors'                                                            => [
+                '<?php $array = [1, 2, 3];',
+                0,
+                [],
+            ],
+            'One syntax error'                                                            => [
+                '<?php $array = [1, 2, 3; // Missing closing bracket.',
+                1,
+                [
+                    1 => [
+                        1 => [
+                            0 => [
+                                'message'  => $errorMessage,
+                                'source'   => 'Generic.PHP.Syntax.PHPSyntax',
+                                'listener' => 'PHP_CodeSniffer\\Standards\\Generic\\Sniffs\\PHP\\SyntaxSniff',
+                                'severity' => 5,
+                                'fixable'  => false,
+                            ],
+                        ],
+                    ],
+                ],
+            ],
+            'Single error reported even when there is more than syntax error in the file' => [
+                '<?php $array = [1, 2, 3; // Missing closing bracket.
+                $anotherArray = [4, 5, 6; // Another missing closing bracket.',
+                1,
+                [
+                    1 => [
+                        1 => [
+                            0 => [
+                                'message'  => $errorMessage,
+                                'source'   => 'Generic.PHP.Syntax.PHPSyntax',
+                                'listener' => 'PHP_CodeSniffer\\Standards\\Generic\\Sniffs\\PHP\\SyntaxSniff',
+                                'severity' => 5,
+                                'fixable'  => false,
+                            ],
+                        ],
+                    ],
+                ],
+            ],
+        ];
+
+    }//end dataStdIn()
+
+
 }//end class