json reporter: resolve relative paths and ensure parent folders exist

lib/reporters/json.js

@@ -1,8 +1,32 @@
 'use strict';
 
 const fs = require('fs');
+const {resolve, isAbsolute, dirname} = require('path');
+
+function writeReport(fileName, data) {
+	try {
+		const dirPath = dirname(fileName);
+		if (!(fs.existsSync(dirPath) && fs.lstatSync(dirPath).isDirectory())) {
+			fs.mkdirSync(dirPath, {recursive: true});
+		}
+		fs.writeFileSync(fileName, data);
+		return true;
+	} catch (error) {
+		console.error(`Unable to write ${fileName}`);
+		console.error(error);
+		return false;
+	}
+}
+
+function resolveFile(fileName) {
+	if (typeof fileName !== 'string') {
+		return null;
+	}
+	return isAbsolute(fileName) ? fileName : resolve(process.cwd(), fileName);
+}
 
 module.exports = function jsonReporter(options = {}) {
+	const fileName = resolveFile(options.fileName);
 	return {
 		afterAll(report) {
 			const jsonString = JSON.stringify(report, (key, value) => {
@@ -15,8 +39,8 @@ module.exports = function jsonReporter(options = {}) {
             // If reporter options specify an output file, write to file.
             // Otherwise, write to console for backwards compatibility with
             // previous --json CLI option.
-			if (options.fileName) {
-				fs.writeFileSync(options.fileName, jsonString);
+			if (fileName) {
+				writeReport(fileName, jsonString);
 			} else {
 				console.log(jsonString);
 			}