Improve coverage UX

lib/tests/run_tests.js

@@ -139,7 +139,7 @@ module.exports = {
               console.log(`Coverage report created. You can find it here: ${fs.dappPath('coverage/index.html')}\n`);
               const opn = require('opn');
               const _next = () => { next(); };
-              opn(fs.dappPath('coverage/index.html'), {wait: false})
+              opn(fs.dappPath('coverage/__root__/index.html'), {wait: false})
                 .then(() => new Promise(resolve => setTimeout(resolve, 1000)))
                 .then(_next, _next);
             });