feat(specs): Add support for generating JUnit XML by passing --junit-xml=<path>

Summary:
A prerequesite to integrating with `arc unit` or CI for each patchset is
being able to generate JUnit XML output for spec runs. This commit adds
this feature using the JUnitXMLReporter from jasmine-reporters. Invoke it like
this:

    npm run test-junit

(We output to the terminal as well when this is run, so in the case that
you're doing `arc diff` you have some idea of what is going on.)

Test Plan: run it

Reviewers: halla, juan, evan

Reviewed By: juan, evan

Differential Revision: https://phab.nylas.com/D3891

.gitignore

@@ -14,6 +14,7 @@ debug.log
 /tags
 /electron/
 /_docs_output
+/junitxml
 
 spec/fixtures/evil-files/
 build/resources/certs

package.json

@@ -48,6 +48,7 @@
     "jasmine-json": "~0.0",
     "jasmine-react-helpers": "^0.2",
     "jasmine-tagged": "^1.1.2",
+    "jasmine-reporters": "1.x.x",
     "jsx-transform": "^2.3.0",
     "juice": "^1.4",
     "kbpgp": "^2.0.52",
@@ -132,6 +133,7 @@
   "scripts": {
     "test": "electron . --test --enable-logging",
     "test-window": "electron . --test=window --enable-logging",
+    "test-junit": "electron . --test --enable-logging --junit-xml=junitxml",
     "start": "electron . --dev --enable-logging",
     "lint": "script/grunt lint",
     "build": "script/grunt build",

spec/n1-spec-runner/n1-spec-runner.es6

@@ -129,24 +129,34 @@ class N1SpecRunner {
     const timeReporter = new TimeReporter();
     const consoleReporter = new ConsoleReporter();
 
-    // This needs to be `required` at runtime because terminal-reporter
-    // depends on jasmine-tagged, which depends on jasmine-focused, which
-    // on require will attempt to extend the `jasmine` object with
-    // methods. The `jasmine` object has to be attached to the global
-    // scope before it gets extended. This is done in
-    // `_extendGlobalWindow`.
-    const N1TerminalReporter = require('./terminal-reporter').default
+    const loadSettings = NylasEnv.getLoadSettings();
 
-    const terminalReporter = new N1TerminalReporter();
-
-    if (NylasEnv.getLoadSettings().showSpecsInWindow) {
-      this.jasmineEnv.addReporter(N1GuiReporter);
-      NylasEnv.show();
-    } else {
-      this.jasmineEnv.addReporter(terminalReporter);
+    if (loadSettings.jUnitXmlPath) {
+      // jasmine-reporters extends the jasmine global with methods, so needs to
+      // be `required` at runtime. The `jasmine` object has to be attached to the
+      // global scope before it gets extended. This is done in
+      // `_extendGlobalWindow`
+      require('jasmine-reporters');
+      const jUnitXmlReporter = new jasmine.JUnitXmlReporter(loadSettings.jUnitXmlPath, true, true);
+      this.jasmineEnv.addReporter(jUnitXmlReporter);
     }
     this.jasmineEnv.addReporter(timeReporter);
     this.jasmineEnv.addReporter(consoleReporter);
+
+    if (loadSettings.showSpecsInWindow) {
+      this.jasmineEnv.addReporter(N1GuiReporter);
+      NylasEnv.show();
+    } else {
+      // this package's dep `jasmine-focused` also adds methods to the
+      // `jasmine` global
+      // NOTE: this reporter MUST be added last as it exits the test process
+      // when complete, which may result in e.g. your XML output not getting
+      // written to disk if that reporter is added afterward.
+      const N1TerminalReporter = require('./terminal-reporter').default
+
+      const terminalReporter = new N1TerminalReporter();
+      this.jasmineEnv.addReporter(terminalReporter);
+    }
   }
 
   _initializeDOM() {

src/browser/application.es6

@@ -113,9 +113,9 @@ export default class Application extends EventEmitter {
     const {specMode, pathsToOpen, urlsToOpen} = options;
 
     if (specMode) {
-      const {resourcePath, specDirectory, specFilePattern, logFile, showSpecsInWindow} = options;
+      const {resourcePath, specDirectory, specFilePattern, logFile, showSpecsInWindow, jUnitXmlPath} = options;
       const exitWhenDone = true;
-      this.runSpecs({exitWhenDone, showSpecsInWindow, resourcePath, specDirectory, specFilePattern, logFile});
+      this.runSpecs({exitWhenDone, showSpecsInWindow, resourcePath, specDirectory, specFilePattern, logFile, jUnitXmlPath});
       return;
     }
 
@@ -762,6 +762,7 @@ export default class Application extends EventEmitter {
   //   :specPath - The directory to load specs from.
   //   :safeMode - A Boolean that, if true, won't run specs from ~/.nylas-mail/packages
   //               and ~/.nylas-mail/dev/packages, defaults to false.
+  //   :jUnitXmlPath - The path to output jUnit XML reports to, if desired.
   runSpecs(specWindowOptionsArg) {
     const specWindowOptions = specWindowOptionsArg;
     let {resourcePath} = specWindowOptions;

src/browser/main.js

@@ -86,6 +86,7 @@ const parseCommandLine = (argv) => {
   const devMode = args['dev'] || args['test'];
   const logFile = args['log-file'];
   const specMode = args['test'];
+  const jUnitXmlPath = args['junit-xml'];
   const safeMode = args['safe'];
   const background = args['background'];
   const configDirPath = args['config-dir-path'];
@@ -129,6 +130,7 @@ const parseCommandLine = (argv) => {
     background,
     logFile,
     specMode,
+    jUnitXmlPath,
     safeMode,
     configDirPath,
     specDirectory,