fix: update the timeout logic to consider also the checkFunction duration

Before this commit, the number of retries was calculated ignoring the checkFunction duration.

As a result, a 5s timeout with a 0.5s interval resulted in 10 retries.
If the checkFunction takes 10 seconds, 10 retries mean waiting for 100 seconds, violating the 5s timeout.

This commit fixes the problem by checking, after each checkFunction invocation, what is the elapsed time and stops retrying in case the timeout is over.

BREAKING CHANGE: The timeout is now respected even if checkFunction takes a long time. As a result,
you could face that your checkFunction runs less times.

fix #464

Author: NoriSte

cypress/e2e/plugin.spec.js

@@ -39,6 +39,38 @@ context('Cypress Wait Until', () => {
     })
   })
 
+  it('Should run once if waitUntil timeout is less than checkFunction execution time', () => {
+    let checks = 0
+    const checkFunction = () => {
+      cy.wait(500).then(() => {
+        checks++
+        return false
+      })
+    }
+
+    cy.once('fail', () => {
+      expect(checks).to.equal(1)
+    })
+
+    cy.waitUntil(checkFunction, { timeout: 400 })
+  })
+
+  it('Should run 3 times if checkFunction + interval is 2s and timeout is 5s', () => {
+    let checks = 0
+    const checkFunction = () => {
+      cy.wait(1500).then(() => {
+        checks++
+        return false
+      })
+    }
+
+    cy.once('fail', () => {
+      expect(checks).to.equal(3)
+    })
+
+    cy.waitUntil(checkFunction, { timeout: 5000, interval: 500 })
+  })
+
   it('Should apply options correctly', () => {
     const COOKIE_NAME = 'after-a-while-cookie'
     const EXPECTED_COOKIE_VALUE = 'Set'

src/index.js

@@ -47,7 +47,7 @@ const waitUntil = (subject, checkFunction, originalOptions = {}) => {
   // filter out a falsy passed "customMessage" value
   options.customMessage = [options.customMessage, originalOptions].filter(Boolean)
 
-  let retries = Math.floor(options.timeout / options.interval)
+  const endTime = Date.now() + options.timeout
 
   logCommand({ options, originalOptions })
 
@@ -56,13 +56,12 @@ const waitUntil = (subject, checkFunction, originalOptions = {}) => {
     if (result) {
       return result
     }
-    if (retries < 1) {
+    if (Date.now() >= endTime) {
       const msg =
         options.errorMsg instanceof Function ? options.errorMsg(result, options) : options.errorMsg
       throw new Error(msg)
     }
     cy.wait(options.interval, { log: false }).then(() => {
-      retries--
       return resolveValue()
     })
   }