allow coverage instrumentation of multiple files

Author: bjouhier

lib/coverage.js

@@ -54,7 +54,9 @@ exports.instrument = function(options) {
     var matcher, instrumenter;
 
     matcher = function (file) {
-        return file === options.code.path;
+        if (typeof options.coverage === 'string') return file.indexOf(options.coverage) === 0;
+        else if (options.coverage instanceof RegExp) return options.coverage.test(file);
+        else return file === options.code.path;
     }
     instrumenter = new istanbul.Instrumenter();
     istanbul.hook.hookRequire(matcher, instrumenter.instrumentSync.bind(instrumenter));