add: unit and integration testing

app/node_modules/istanbul-reports/lib/text-lcov/index.js

@@ -0,0 +1,17 @@
+'use strict';
+/*
+ Copyright 2012-2015, Yahoo Inc.
+ Copyrights licensed under the New BSD License. See the accompanying LICENSE file for terms.
+ */
+const LcovOnly = require('../lcovonly');
+
+class TextLcov extends LcovOnly {
+    constructor(opts) {
+        super({
+            ...opts,
+            file: '-'
+        });
+    }
+}
+
+module.exports = TextLcov;