feat: 🎸 Makre the plugin chainable

Closes: #40

README.md

@@ -65,6 +65,19 @@ cy.waitUntil(() => cy.get("input[type=hidden]#recaptchatoken").then($el => $el.v
   .then(token => expect(token).to.be.a("string").to.have.length.within(1, 1000));
 ```
 
+The `waitUntil` command could be chained to other commands too. As an example, the following codes are equivalent
+```javascript
+cy.waitUntil(() => cy.getCookie('token').then(cookie => cookie.value === '<EXPECTED_VALUE>'));
+// is equivalent to
+cy.wrap('<EXPECTED_VALUE>')
+  .waitUntil((subject) => cy.getCookie('token').then(cookie => cookie.value === subject));
+```
+Please note: do not expect that the previous command are retried. Only what's inside the `checkFunction` code is retried
+```javascript
+cy.getCookie('token') // will not be retried
+  .waitUntil(cookie => cookie.value === '<EXPECTED_VALUE>');
+```
+
 
 ### TypeScript
 

cypress/integration/plugin.spec.js

@@ -151,4 +151,17 @@ context('Actions', () => {
     cy.log("Chainable function");
     cy.waitUntil(chainableCheckFunction, {interval})
   })
+
+  it('Should be chainable', () => {
+    const result = 10;
+    const checkFunction = () => result;
+    const checkFunctionWithSubject = subject => subject;
+
+    cy.waitUntil(checkFunction)
+      .should('eq', result)
+
+    cy.wrap(result)
+      .waitUntil(checkFunctionWithSubject)
+      .should('eq', result)
+  })
 })

package.json

@@ -1,6 +1,6 @@
 {
   "name": "cypress-wait-until",
-  "version": "1.3.2",
+  "version": "1.4.0",
   "description": "A waiting plugin for Cypress",
   "main": "src/index.js",
   "dependencies": {},

src/index.js

@@ -1,6 +1,6 @@
 'use strict'
 
-function waitUntil(checkFunction, options) {
+function waitUntil(subject, checkFunction, options) {
   if (!(checkFunction instanceof Function)) {
     throw new Error('`checkFunction` parameter should be a function. Found: ' + checkFunction)
   }
@@ -25,7 +25,7 @@ function waitUntil(checkFunction, options) {
   }
 
   const resolveValue = () => {
-    const result = checkFunction()
+    const result = checkFunction(subject)
     const isAPromise = Boolean(result && result.then)
 
     if (isAPromise) {
@@ -38,4 +38,4 @@ function waitUntil(checkFunction, options) {
   return resolveValue()
 }
 
-Cypress.Commands.add("waitUntil", waitUntil);
+Cypress.Commands.add("waitUntil", {prevSubject:'optional'}, waitUntil);