Fix platform inconsistency with empty values

An unexpected `false` or `null` value was handled inconsistently across
platforms, returning an empty string on Windows, otherwise `''`. This
is fixed to return `""` on Windows.

Author: johnstevenson

.gitignore

@@ -1,4 +1,6 @@
 composer.lock
 phpcs.xml
 phpunit.xml
+.phpunit.result.cache
 vendor/
+

src/Args.php

@@ -39,7 +39,7 @@ public static function escape($arg, $meta = true, $module = false)
         }
 
         // Check for whitespace or an empty value
-        $quote = strpbrk($arg, " \t") !== false || $arg === '';
+        $quote = strpbrk($arg, " \t") !== false || (string) $arg === '';
 
         // Escape double-quotes and double-up preceding backslashes
         $arg = preg_replace('/(\\\\*)"/', '$1$1\\"', $arg, -1, $dquotes);

tests/ArgsTest.php

@@ -49,13 +49,22 @@ public function testCommandLine()
         }
 
         $params = array(PHP_BINARY, __DIR__.DIRECTORY_SEPARATOR.'args.php');
+        $args = array();
         $expected = array();
 
         foreach ($this->dataArguments() as $test) {
-            $expected[] = $test[0];
+            $arg = $test[0];
+
+            if ($arg === null || $arg === false) {
+                $expected[] = '';
+            } else {
+                $expected[] = $arg;
+            }
+
+            $args[] = $arg;
         }
 
-        $params = array_merge($params, $expected);
+        $params = array_merge($params, $args);
         $command = Args::escapeCommand($params);
 
         exec($command, $lines);
@@ -74,6 +83,12 @@ public function dataArguments()
             // empty argument - must be quoted
             'empty'         => array('', '""', "''", 0),
 
+            // false argument - must be quoted
+            'empty false'   => array(false, '""', "''", 0),
+
+            // null argument - must be quoted
+            'empty null'    => array(null, '""', "''", 0),
+
             // unix single-quote must be escaped
             'unix-sq'       => array("a'bc", "a'bc", "'a'\\''bc'", 0),