Merge pull request #117 from vatesfr/promise-settle

Implement utils.pSettle().

src/utils.js

@@ -106,6 +106,32 @@ export function pFinally (cb) {
   )
 }
 
+// Given an array which contains promises return a promise that is
+// fulfilled when all the items in the array are either fulfilled or
+// rejected.
+export function pSettle (promises) {
+  const statuses = promises.map(promise => promise.then(
+    value => ({
+      isFulfilled: () => true,
+      isRejected: () => false,
+      value: () => value,
+      reason: () => {
+        throw new Error('no reason, the promise has been fulfilled')
+      }
+    }),
+    reason => ({
+      isFulfilled: () => false,
+      isRejected: () => true,
+      value: () => {
+        throw new Error('no value, the promise has been rejected')
+      },
+      reason: () => reason
+    })
+  ))
+
+  return Promise.all(statuses)
+}
+
 // -------------------------------------------------------------------
 
 export {

src/utils.spec.js

@@ -13,7 +13,8 @@ import {
   formatXml,
   generateToken,
   parseSize,
-  pFinally
+  pFinally,
+  pSettle
 } from './utils'
 
 // ===================================================================
@@ -170,3 +171,29 @@ describe('pFinally()', () => {
     expect(spy.callCount).to.equal(1)
   })
 })
+
+// -------------------------------------------------------------------
+
+describe('pSettle()', () => {
+  it('makes an array of PromiseInspection', async () => {
+    const [
+      status1,
+      status2
+    ] = await pSettle([
+      Promise.resolve(42),
+      Promise.reject('fatality')
+    ])
+
+    expect(status1.isRejected()).to.equal(false)
+    expect(status2.isRejected()).to.equal(true)
+
+    expect(status1.isFulfilled()).to.equal(true)
+    expect(status2.isFulfilled()).to.equal(false)
+
+    expect(status1.value()).to.equal(42)
+    expect(::status2.value).to.throw()
+
+    expect(::status1.reason).to.throw()
+    expect(status2.reason()).to.equal('fatality')
+  })
+})