add regex based context to test stdout

Author: miya0001

features/steps/then.php

@@ -199,8 +199,8 @@ function ( $world, $path, $type, $action, $expected = null ) {
 	}
 );
 
-$steps->Then( '/^the (.+) file should match (((\/.+\/)|(#.+#))([a-z]+)?)$/',
-function ( $world, $path, $expected = null ) {
+$steps->Then( '/^the contents of the (.+) file should match (((\/.+\/)|(#.+#))([a-z]+)?)$/',
+function ( $world, $path, $expected ) {
 	$path = $world->replace_variables( $path );
 
 	// If it's a relative path, make it relative to the current test dir
@@ -213,6 +213,14 @@ function ( $world, $path, $expected = null ) {
 }
 );
 
+$steps->Then( '/^(STDOUT|STDERR) should match (((\/.+\/)|(#.+#))([a-z]+)?)$/',
+function ( $world, $stream, $expected ) {
+
+	$stream = strtolower( $stream );
+	assertRegExp( $expected, $world->result->$stream );
+}
+);
+
 $steps->Then( '/^an email should (be sent|not be sent)$/', function( $world, $expected ) {
 	if ( 'be sent' === $expected ) {
 		assertNotEquals( 0, $world->email_sends );