Add unhandledRejection to default value of exitOn option

Author: ehmicky

README.md

@@ -115,7 +115,8 @@ Which log level to use.\
 ## exitOn
 
 _Type_: `string[]`\
-_Default_: `['uncaughtException']`
+_Default_: `['uncaughtException', 'unhandledRejection']` for Node `>= 15.0.0`, `['uncaughtException']`
+otherwise.
 
 Which process errors should trigger `process.exit(1)`.\
 [Full documentation](docs/API.md#exiton).

docs/API.md

@@ -109,15 +109,15 @@ _Value_: array of [`'uncaughtException'`](https://nodejs.org/api/process.html#pr
 [`'rejectionHandled'`](https://nodejs.org/api/process.html#process_event_rejectionhandled),
 [`'multipleResolves'`](https://nodejs.org/api/process.html#process_event_multipleresolves)
 or [`'warning'`](https://nodejs.org/api/process.html#process_event_warning)\
-_Default_: `['uncaughtException']`
+_Default_: `['uncaughtException', 'unhandledRejection']` for Node `>= 15.0.0`,
+`['uncaughtException']` otherwise.
 
 Which process errors should trigger `process.exit(1)`:
 
-- `['uncaughtException']` is Node.js
-  [default behavior](https://nodejs.org/api/process.html#process_warning_using_uncaughtexception_correctly).
-- we recommend using `['uncaughtException', 'unhandledRejection']` instead since
-  this will be
-  [Node.js future default behavior](https://nodejs.org/dist/latest-v8.x/docs/api/deprecations.html#deprecations_dep0018_unhandled_promise_rejections).
+- `['uncaughtException', 'unhandledRejection']` is Node.js default behavior
+  since Node.js `15.0.0`. Before, only
+  [`uncaughtException`](https://nodejs.org/api/process.html#process_warning_using_uncaughtexception_correctly)
+  was enabled.
 - use `[]` to prevent any `process.exit(1)`. Recommended if your process is
   long-running and does not automatically restart on exit.
 

package-lock.json

@@ -57,6 +57,7 @@
     "jest-validate": "^26.6.1",
     "map-obj": "^4.1.0",
     "moize": "^6.0.0-beta.5",
+    "semver": "^7.3.2",
     "supports-color": "^7.2.0"
   },
   "devDependencies": {
@@ -69,7 +70,6 @@
     "husky": "^4.3.0",
     "jasmine": "^3.6.1",
     "mocha": "^8.2.0",
-    "semver": "^7.3.2",
     "sinon": "^9.2.0",
     "strip-ansi": "^6.0.0",
     "tap": "^14.10.8",

package.json

@@ -4,10 +4,7 @@ import process from 'process'
 // Exit process according to `opts.exitOn` (default: ['uncaughtException']):
 //  - `uncaughtException`: default behavior of Node.js and recommended by
 //     https://nodejs.org/api/process.html#process_warning_using_uncaughtexception_correctly
-//  - `unhandledRejection`: possible future behavior and recommended by Node.js.
-//    See https://nodejs.org/dist/latest-v8.x/docs/api/deprecations.html#deprecations_dep0018_unhandled_promise_rejections
-// By default `unhandledRejection` is opt-in so that using this library does not
-// decrease stability (if the application does not restart on exit).
+//  - `unhandledRejection`: default behavior of Node.js since 15.0.0
 // `process.exit()` unfortunately aborts any current async operations and
 // streams are not flushed (including stdout/stderr):
 //  - https://github.com/nodejs/node/issues/784

src/exit.js

@@ -1,5 +1,8 @@
+import { version } from 'process'
+
 import filterObj from 'filter-obj'
 import { validate } from 'jest-validate'
+import { gte as gteVersion } from 'semver'
 
 import { addChalk, DEFAULT_COLORS } from '../colors.js'
 import { validateExitOn } from '../exit.js'
@@ -31,9 +34,25 @@ const isDefined = function (key, value) {
   return value !== undefined
 }
 
+// Since Node 15.0.0, `unhandledRejection` makes the process exit too
+// TODO: remove after dropping support for Node <15.0.0
+const getDefaultExitOn = function () {
+  if (isNewExitBehavior()) {
+    return ['uncaughtException', 'unhandledRejection']
+  }
+
+  return ['uncaughtException']
+}
+
+const isNewExitBehavior = function () {
+  return gteVersion(version, NEW_EXIT_MIN_VERSION)
+}
+
+const NEW_EXIT_MIN_VERSION = '15.0.0'
+
 const DEFAULT_OPTS = {
   log: defaultLog,
-  exitOn: ['uncaughtException'],
+  exitOn: getDefaultExitOn(),
   colors: DEFAULT_COLORS,
 }
 

src/options/main.js

@@ -1,11 +1,26 @@
 import { version } from 'process'
 
-import semver from 'semver'
+import { gte as gteVersion, lt as ltVersion } from 'semver'
 
 // TODO: remove after dropping support for Node <12.0.0
 // `--unhandled-rejections` was introduced in Node `12.0.0`
 export const hasUnhandledFlag = function () {
-  return semver.gte(version, UNHANDLED_FLAG_V)
+  return gteVersion(version, UNHANDLED_FLAG_VERSION)
 }
 
-const UNHANDLED_FLAG_V = '12.0.0'
+const UNHANDLED_FLAG_VERSION = '12.0.0'
+
+// Node 15.0.0 changed the default exit behavior on unhandled promises
+export const hasOldExitBehavior = function (eventName) {
+  return (
+    PROMISE_REJECTION_EVENTS.has(eventName) &&
+    ltVersion(version, NEW_EXIT_MIN_VERSION)
+  )
+}
+
+const PROMISE_REJECTION_EVENTS = new Set([
+  'unhandledRejection',
+  'rejectionHandled',
+])
+
+const NEW_EXIT_MIN_VERSION = '15.0.0'

test/helpers/events/version.js

@@ -2,6 +2,7 @@ import test from 'ava'
 import { each } from 'test-each'
 
 import { EVENTS } from './helpers/events/main.js'
+import { hasOldExitBehavior } from './helpers/events/version.js'
 import { normalizeCall } from './helpers/normalize.js'
 import { removeProcessListeners } from './helpers/remove.js'
 
@@ -11,6 +12,11 @@ removeProcessListeners()
 
 each(EVENTS, ({ title }, { eventName }) => {
   test(`should work using the -r flag | ${title}`, async (t) => {
+    if (hasOldExitBehavior(eventName)) {
+      t.pass()
+      return
+    }
+
     t.snapshot(
       await normalizeCall(`node ${LOADERS}/register.js ${eventName}`, {
         colors: false,

test/options/snapshots/testing.js.snap

@@ -72,7 +72,7 @@ Generated by [AVA](https://avajs.dev).
 > Snapshot 1
 
     {
-      exitCode: 0,
+      exitCode: 1,
       stderr: `×  unhandledRejection (a promise was rejected but not handled)  Error: message␊
           at STACK TRACE␊
        ×  rejectionHandled (a promise was rejected and handled too late)  Error: message␊
@@ -96,7 +96,7 @@ Generated by [AVA](https://avajs.dev).
 > Snapshot 1
 
     {
-      exitCode: 0,
+      exitCode: 1,
       stderr: `×  unhandledRejection (a promise was rejected but not handled)  Error: message␊
           at STACK TRACE`,
       stdout: '',