Fix.

node_modules/istanbul-reports/lib/json-summary/index.js

@@ -0,0 +1,48 @@
+/*
+ Copyright 2012-2015, Yahoo Inc.
+ Copyrights licensed under the New BSD License. See the accompanying LICENSE file for terms.
+ */
+'use strict';
+
+function JsonSummaryReport(opts) {
+    this.file = opts.file || 'coverage-summary.json';
+    this.contentWriter = null;
+    this.first = true;
+}
+
+JsonSummaryReport.prototype.onStart = function(root, context) {
+    this.contentWriter = context.writer.writeFile(this.file);
+    this.contentWriter.write('{');
+};
+
+JsonSummaryReport.prototype.writeSummary = function(filePath, sc) {
+    const cw = this.contentWriter;
+    if (this.first) {
+        this.first = false;
+    } else {
+        cw.write(',');
+    }
+    cw.write(JSON.stringify(filePath));
+    cw.write(': ');
+    cw.write(JSON.stringify(sc));
+    cw.println('');
+};
+
+JsonSummaryReport.prototype.onSummary = function(node) {
+    if (!node.isRoot()) {
+        return;
+    }
+    this.writeSummary('total', node.getCoverageSummary());
+};
+
+JsonSummaryReport.prototype.onDetail = function(node) {
+    this.writeSummary(node.getFileCoverage().path, node.getCoverageSummary());
+};
+
+JsonSummaryReport.prototype.onEnd = function() {
+    const cw = this.contentWriter;
+    cw.println('}');
+    cw.close();
+};
+
+module.exports = JsonSummaryReport;