{"id":12227,"date":"2025-05-06T10:00:33","date_gmt":"2025-05-06T10:00:33","guid":{"rendered":"https:\/\/www.bacancytechnology.com\/qanda\/?p=12227"},"modified":"2025-05-19T12:01:25","modified_gmt":"2025-05-19T12:01:25","slug":"cypress-mock-internal-variable-value-inside-function","status":"publish","type":"post","link":"https:\/\/www.bacancytechnology.com\/qanda\/react\/cypress-mock-internal-variable-value-inside-function","title":{"rendered":"Can Cypress Mock Internal Variable Value Inside Function In Runtime Like Jest Does?"},"content":{"rendered":"<h3>Cypress and Jest serve different purposes:<\/h3>\n<ul>\n<li><strong>Jest<\/strong> is a unit testing framework that allows mocking functions, modules, and variables at runtime.<\/li>\n<li><strong>Cypress<\/strong> is an end-to-end testing framework that runs in a browser, which makes it difficult to mock internal variables in runtime like Jest does.<\/li>\n<\/ul>\n<h3>Can Cypress mock internal variables inside a function at runtime?<\/h3>\n<p>No, Cypress cannot mock internal variables inside a function at runtime like Jest. It runs in a browser and lacks Jest&#8217;s runtime control.<\/p>\n<h2>Alternatives in Cypress<\/h2>\n<h3>1. Stub Functions (cy.stub()) \u2013 If the function is accessible on window<\/h3>\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"r\">\r\ncy.window().then((win) =&gt; {\r\n  cy.stub(win, 'getActionTypeName').returns('RUNTIME_RESET_TYPE');\r\n});\r\n<\/pre>\n<h3>2. Dependency Injection \u2013 Refactor the function to accept dependencies<\/h3>\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"r\">\r\nexport const functionBeingTested = (getActionTypeName) => {\r\n  return getActionTypeName();\r\n};\r\n<\/pre>\n<p>Then in your Cypress test:<\/p>\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"r\">\r\ncy.wrap(() => 'RUNTIME_RESET_TYPE').as('mockFn');\r\ncy.get('@mockFn').then((mockFn) => {\r\n  expect(functionBeingTested(mockFn)).to.eq('RUNTIME_RESET_TYPE');\r\n});\r\n<\/pre>\n<h3>3. Intercept API Calls (cy.intercept()) \u2013 Mock API responses:<\/h3>\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"r\">\r\ncy.intercept('GET', '\/api\/action-type', { actionType: 'RUNTIME_RESET_TYPE' });\r\n<\/pre>\n<h3>4. Use Environment Variables \u2013 Control behavior via Cypress config<\/h3>\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"r\">\r\nCypress.env('ACTION_TYPE', 'RUNTIME_RESET_TYPE');\r\n<\/pre>\n<p>Then in your app:<\/p>\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"r\">\r\nconst actionType = Cypress.env('ACTION_TYPE') || getActionTypeName();\r\n<\/pre>\n<h2>Conclusion<\/h2>\n<p>While Cypress can&#8217;t mock internal variables like Jest, it offers workarounds through stubbing, dependency injection, API interception, and environment variables.<\/p>\n<div class=\"qanda-read-box\"><div class=\"bg-light read-more-icon\"><img decoding=\"async\" src=\"https:\/\/assets.bacancytechnology.com\/qanda\/wp-content\/uploads\/2025\/04\/24061434\/read-txt.png\" alt=\"Also Read\"><p><\/p><h3>Also Read:<\/h3><a href=\"https:\/\/www.bacancytechnology.com\/blog\/react-carousel\" target=\"_blank\">Top 15 React Carousel Component<\/a><\/div><\/div>\n","protected":false},"excerpt":{"rendered":"<p>Cypress and Jest serve different purposes: Jest is a unit testing framework that allows mocking functions, modules, and variables at runtime. Cypress is an end-to-end testing framework that runs in a browser, which makes it difficult to mock internal variables in runtime like Jest does. Can Cypress mock internal variables inside a function at runtime? [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":12228,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"inline_featured_image":false,"footnotes":""},"categories":[1],"tags":[],"class_list":["post-12227","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-react"],"acf":[],"_links":{"self":[{"href":"https:\/\/www.bacancytechnology.com\/qanda\/wp-json\/wp\/v2\/posts\/12227"}],"collection":[{"href":"https:\/\/www.bacancytechnology.com\/qanda\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.bacancytechnology.com\/qanda\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.bacancytechnology.com\/qanda\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.bacancytechnology.com\/qanda\/wp-json\/wp\/v2\/comments?post=12227"}],"version-history":[{"count":4,"href":"https:\/\/www.bacancytechnology.com\/qanda\/wp-json\/wp\/v2\/posts\/12227\/revisions"}],"predecessor-version":[{"id":12375,"href":"https:\/\/www.bacancytechnology.com\/qanda\/wp-json\/wp\/v2\/posts\/12227\/revisions\/12375"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.bacancytechnology.com\/qanda\/wp-json\/wp\/v2\/media\/12228"}],"wp:attachment":[{"href":"https:\/\/www.bacancytechnology.com\/qanda\/wp-json\/wp\/v2\/media?parent=12227"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.bacancytechnology.com\/qanda\/wp-json\/wp\/v2\/categories?post=12227"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.bacancytechnology.com\/qanda\/wp-json\/wp\/v2\/tags?post=12227"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}