feat: add allowThenStrict option; fixes #52

Author: brettz9

__tests__/catch-or-return.js

@@ -89,6 +89,37 @@ ruleTester.run('catch-or-return', rule, {
  options: [{ allowThen: true }],
  },
 
+ // allowThenStrict - .then(null, fn)
+ {
+ code: 'frank().then(go).then(null, doIt)',
+ options: [{ allowThenStrict: true }],
+ },
+ {
+ code: 'frank().then(go).then().then().then().then(null, doIt)',
+ options: [{ allowThenStrict: true }],
+ },
+ {
+ code: 'frank().then(go).then().then(null, function() { /* why bother */ })',
+ options: [{ allowThenStrict: true }],
+ },
+ {
+ code: 'frank.then(go).then(to).then(null, jail)',
+ options: [{ allowThenStrict: true }],
+ },
+
+ {
+ code: 'frank().then(a).then(b).then(null, c)',
+ options: [{ allowThenStrict: true }],
+ },
+ {
+ code: 'frank().then(a).then(b).then().then().then(null, doIt)',
+ options: [{ allowThenStrict: true }],
+ },
+ {
+ code: 'frank().then(a).then(b).then(null, function() { /* why bother */ })',
+ options: [{ allowThenStrict: true }],
+ },
+
  // allowFinally - .finally(fn)
  {
  code: 'frank().then(go).catch(doIt).finally(fn)',
@@ -273,5 +304,36 @@ ruleTester.run('catch-or-return', rule, {
  code: 'frank.then(go).then(to).then(pewPew, jail)',
  errors: [{ message: catchMessage }],
  },
+
+ {
+ code: 'frank().then(a, b)',
+ errors: [{ message: catchMessage }],
+ options: [{ allowThenStrict: true }],
+ },
+ {
+ code: 'frank().then(go).then(zam, doIt)',
+ errors: [{ message: catchMessage }],
+ options: [{ allowThenStrict: true }],
+ },
+ {
+ code: 'frank().then(a).then(b).then(c, d)',
+ errors: [{ message: catchMessage }],
+ options: [{ allowThenStrict: true }],
+ },
+ {
+ code: 'frank().then(go).then().then().then().then(wham, doIt)',
+ errors: [{ message: catchMessage }],
+ options: [{ allowThenStrict: true }],
+ },
+ {
+ code: 'frank().then(go).then().then(function() {}, function() { /* why bother */ })',
+ errors: [{ message: catchMessage }],
+ options: [{ allowThenStrict: true }],
+ },
+ {
+ code: 'frank.then(go).then(to).then(pewPew, jail)',
+ errors: [{ message: catchMessage }],
+ options: [{ allowThenStrict: true }],
+ },
  ],
 })

docs/rules/catch-or-return.md

@@ -55,6 +55,34 @@ myPromise.then(null, handleErrors)
 myPromise.then(doSomething).catch(handleErrors)
 ```
 
+##### `allowThenStrict`
+
+`allowThenStrict` is similar to `allowThen` but it only permits `then` when the
+fulfillment handler is `null`. This option ensures that the final rejected
+handler works like a `catch` and can handle any uncaught errors from the final
+`then`.
+
+Examples of **incorrect** code for the default `{ allowThenStrict: false }`
+option:
+
+```js
+myPromise.then(doSomething, handleErrors)
+myPromise.then(null, handleErrors)
+```
+
+Examples of **correct** code for the `{ allowThenStrict: true }` option:
+
+```js
+myPromise.then(null, handleErrors)
+myPromise.then(doSomething).catch(handleErrors)
+```
+
+Examples of **incorrect** code for the `{ allowThenStrict: true }` option:
+
+```js
+myPromise.then(doSomething, handleErrors)
+```
+
 ##### `allowFinally`
 
 You can pass an `{ allowFinally: true }` as an option to this rule to allow for

rules/catch-or-return.js

@@ -30,6 +30,9 @@ module.exports = {
  allowThen: {
  type: 'boolean',
  },
+ allowThenStrict: {
+ type: 'boolean',
+ },
  terminationMethod: {
  oneOf: [
  { type: 'string' },
@@ -49,6 +52,7 @@ module.exports = {
  create(context) {
  const options = context.options[0] || {}
  const allowThen = options.allowThen
+ const allowThenStrict = options.allowThenStrict
  const allowFinally = options.allowFinally
  let terminationMethod = options.terminationMethod || 'catch'
 
@@ -59,11 +63,15 @@ module.exports = {
  function isAllowedPromiseTermination(expression) {
  // somePromise.then(a, b)
  if (
- allowThen &&
+ (allowThen || allowThenStrict) &&
  expression.type === 'CallExpression' &&
  expression.callee.type === 'MemberExpression' &&
  expression.callee.property.name === 'then' &&
- expression.arguments.length === 2
+ expression.arguments.length === 2 &&
+ // somePromise.then(null, b)
+ ((allowThen && !allowThenStrict) ||
+ (expression.arguments[0].type === 'Literal' &&
+ expression.arguments[0].value === null))
  ) {
  return true
  }