Add support for relative parent paths (#78)

index.js

@@ -13,8 +13,19 @@ module.exports = function (pattern, options) {
 	}
 
 	return streamfilter(function (file, enc, cb) {
-		var match = typeof pattern === 'function' ? pattern(file) :
-			multimatch(path.relative(file.cwd, file.path), pattern, options).length > 0;
+		var match;
+		if (typeof pattern === 'function') {
+			match = pattern(file);
+		} else {
+			var relPath = path.relative(file.cwd, file.path);
+			// if the path leaves the current working directory, then we need to
+			// resolve the absolute path so that the path can be properly matched
+			// by minimatch (via multimatch)
+			if (relPath.indexOf('../') === 0) {
+				relPath = path.resolve(relPath);
+			}
+			match = multimatch(relPath, pattern, options).length > 0;
+		}
 
 		cb(!match);
 	}, {

test.js

@@ -160,6 +160,28 @@ describe('filter()', function () {
 
 		stream.end();
 	});
+
+	it('should filter relative paths that leave current directory tree', function (cb) {
+		var stream = filter('**/test/**/*.js');
+		var buffer = [];
+		var gfile = path.join('..', '..', 'test', 'included.js');
+
+		stream.on('data', function (file) {
+			buffer.push(file);
+		});
+
+		stream.on('end', function () {
+			assert.equal(buffer.length, 1);
+			assert.equal(buffer[0].relative, gfile);
+			cb();
+		});
+
+		stream.write(new gutil.File({
+			path: gfile
+		}));
+
+		stream.end();
+	});
 });
 
 describe('filter.restore', function () {