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class="nx-overflow-y-auto nx-overflow-x-hidden nx-p-4 nx-grow md:nx-h-[calc(100vh-var(--nextra-navbar-height)-var(--nextra-menu-height))] nextra-scrollbar"><div class="nx-transform-gpu nx-overflow-hidden nx-transition-all nx-ease-in-out motion-reduce:nx-transition-none"><div class="nx-transition-opacity nx-duration-500 nx-ease-in-out motion-reduce:nx-transition-none nx-opacity-100"><ul class="nx-flex nx-flex-col nx-gap-1 nextra-menu-desktop max-md:nx-hidden"><li class="nx-flex nx-flex-col nx-gap-1"><a class="nx-flex nx-rounded nx-px-2 nx-py-1.5 nx-text-sm nx-transition-colors [word-break:break-word] nx-cursor-pointer [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] contrast-more:nx-border nx-text-gray-500 hover:nx-bg-gray-100 hover:nx-text-gray-900 dark:nx-text-neutral-400 dark:hover:nx-bg-primary-100/5 dark:hover:nx-text-gray-50 contrast-more:nx-text-gray-900 contrast-more:dark:nx-text-gray-50 contrast-more:nx-border-transparent contrast-more:hover:nx-border-gray-900 contrast-more:dark:hover:nx-border-gray-50" href="/">Introduction</a></li><li class="nx-flex nx-flex-col nx-gap-1"><a class="nx-flex nx-rounded nx-px-2 nx-py-1.5 nx-text-sm nx-transition-colors [word-break:break-word] nx-cursor-pointer [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] contrast-more:nx-border nx-text-gray-500 hover:nx-bg-gray-100 hover:nx-text-gray-900 dark:nx-text-neutral-400 dark:hover:nx-bg-primary-100/5 dark:hover:nx-text-gray-50 contrast-more:nx-text-gray-900 contrast-more:dark:nx-text-gray-50 contrast-more:nx-border-transparent contrast-more:hover:nx-border-gray-900 contrast-more:dark:hover:nx-border-gray-50" href="/getting-started">Getting Started</a></li><li class="nx-flex nx-flex-col nx-gap-1"><a class="nx-flex nx-rounded nx-px-2 nx-py-1.5 nx-text-sm nx-transition-colors [word-break:break-word] nx-cursor-pointer [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] 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contrast-more:dark:hover:nx-border-gray-50">Features<svg fill="none" viewBox="0 0 24 24" stroke="currentColor" class="nx-h-[18px] nx-min-w-[18px] nx-rounded-sm nx-p-0.5 hover:nx-bg-gray-800/5 dark:hover:nx-bg-gray-100/5"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M9 5l7 7-7 7" class="nx-origin-center nx-transition-transform rtl:-nx-rotate-180 ltr:nx-rotate-90 rtl:nx-rotate-[-270deg]"></path></svg></button><div class="nx-transform-gpu nx-overflow-hidden nx-transition-all nx-ease-in-out motion-reduce:nx-transition-none"><div class="nx-transition-opacity nx-duration-500 nx-ease-in-out motion-reduce:nx-transition-none nx-opacity-100 ltr:nx-pr-0 rtl:nx-pl-0 nx-pt-1"><ul class="nx-flex nx-flex-col nx-gap-1 nx-relative before:nx-absolute before:nx-inset-y-1 before:nx-w-px before:nx-bg-gray-200 before:nx-content-[""] dark:before:nx-bg-neutral-800 ltr:nx-pl-3 ltr:before:nx-left-0 rtl:nx-pr-3 rtl:before:nx-right-0 ltr:nx-ml-3 rtl:nx-mr-3"><li class="nx-flex 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dark:hover:nx-text-gray-50 contrast-more:nx-text-gray-900 contrast-more:dark:nx-text-gray-50 contrast-more:nx-border-transparent contrast-more:hover:nx-border-gray-900 contrast-more:dark:hover:nx-border-gray-50" href="/features/polyfills">Polyfills</a></li><li class="nx-flex nx-flex-col nx-gap-1"><a class="nx-flex nx-rounded nx-px-2 nx-py-1.5 nx-text-sm nx-transition-colors [word-break:break-word] nx-cursor-pointer [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] contrast-more:nx-border nx-text-gray-500 hover:nx-bg-gray-100 hover:nx-text-gray-900 dark:nx-text-neutral-400 dark:hover:nx-bg-primary-100/5 dark:hover:nx-text-gray-50 contrast-more:nx-text-gray-900 contrast-more:dark:nx-text-gray-50 contrast-more:nx-border-transparent contrast-more:hover:nx-border-gray-900 contrast-more:dark:hover:nx-border-gray-50" href="/features/typescript-support">TypeScript support</a></li><li class="nx-flex nx-flex-col nx-gap-1"><a class="nx-flex nx-rounded nx-px-2 nx-py-1.5 nx-text-sm nx-transition-colors [word-break:break-word] nx-cursor-pointer [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] contrast-more:nx-border nx-text-gray-500 hover:nx-bg-gray-100 hover:nx-text-gray-900 dark:nx-text-neutral-400 dark:hover:nx-bg-primary-100/5 dark:hover:nx-text-gray-50 contrast-more:nx-text-gray-900 contrast-more:dark:nx-text-gray-50 contrast-more:nx-border-transparent contrast-more:hover:nx-border-gray-900 contrast-more:dark:hover:nx-border-gray-50" href="/features/upgrading-nextjs">Upgrading Nextjs</a></li></ul></div></div></li><li class="open"><button class="nx-items-center nx-justify-between nx-gap-2 nx-text-left nx-w-full nx-flex nx-rounded nx-px-2 nx-py-1.5 nx-text-sm nx-transition-colors [word-break:break-word] nx-cursor-pointer [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] contrast-more:nx-border nx-text-gray-500 hover:nx-bg-gray-100 hover:nx-text-gray-900 dark:nx-text-neutral-400 dark:hover:nx-bg-primary-100/5 dark:hover:nx-text-gray-50 contrast-more:nx-text-gray-900 contrast-more:dark:nx-text-gray-50 contrast-more:nx-border-transparent contrast-more:hover:nx-border-gray-900 contrast-more:dark:hover:nx-border-gray-50">Packages<svg fill="none" viewBox="0 0 24 24" stroke="currentColor" class="nx-h-[18px] nx-min-w-[18px] nx-rounded-sm nx-p-0.5 hover:nx-bg-gray-800/5 dark:hover:nx-bg-gray-100/5"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M9 5l7 7-7 7" class="nx-origin-center nx-transition-transform rtl:-nx-rotate-180 ltr:nx-rotate-90 rtl:nx-rotate-[-270deg]"></path></svg></button><div class="nx-transform-gpu nx-overflow-hidden nx-transition-all nx-ease-in-out motion-reduce:nx-transition-none"><div class="nx-transition-opacity nx-duration-500 nx-ease-in-out motion-reduce:nx-transition-none nx-opacity-100 ltr:nx-pr-0 rtl:nx-pl-0 nx-pt-1"><ul class="nx-flex nx-flex-col nx-gap-1 nx-relative before:nx-absolute before:nx-inset-y-1 before:nx-w-px before:nx-bg-gray-200 before:nx-content-[""] dark:before:nx-bg-neutral-800 ltr:nx-pl-3 ltr:before:nx-left-0 rtl:nx-pr-3 rtl:before:nx-right-0 ltr:nx-ml-3 rtl:nx-mr-3"><li class="nx-flex nx-flex-col nx-gap-1"><a class="nx-flex nx-rounded nx-px-2 nx-py-1.5 nx-text-sm nx-transition-colors [word-break:break-word] nx-cursor-pointer [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] contrast-more:nx-border nx-text-gray-500 hover:nx-bg-gray-100 hover:nx-text-gray-900 dark:nx-text-neutral-400 dark:hover:nx-bg-primary-100/5 dark:hover:nx-text-gray-50 contrast-more:nx-text-gray-900 contrast-more:dark:nx-text-gray-50 contrast-more:nx-border-transparent contrast-more:hover:nx-border-gray-900 contrast-more:dark:hover:nx-border-gray-50" href="/packages/cookies">@edge-runtime/cookies</a></li><li class="nx-flex nx-flex-col nx-gap-1"><a class="nx-flex nx-rounded nx-px-2 nx-py-1.5 nx-text-sm nx-transition-colors [word-break:break-word] nx-cursor-pointer [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] contrast-more:nx-border nx-text-gray-500 hover:nx-bg-gray-100 hover:nx-text-gray-900 dark:nx-text-neutral-400 dark:hover:nx-bg-primary-100/5 dark:hover:nx-text-gray-50 contrast-more:nx-text-gray-900 contrast-more:dark:nx-text-gray-50 contrast-more:nx-border-transparent contrast-more:hover:nx-border-gray-900 contrast-more:dark:hover:nx-border-gray-50" href="/packages/format">@edge-runtime/format</a></li><li class="nx-flex nx-flex-col nx-gap-1 active"><a class="nx-flex nx-rounded nx-px-2 nx-py-1.5 nx-text-sm nx-transition-colors [word-break:break-word] nx-cursor-pointer [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] contrast-more:nx-border nx-bg-primary-100 nx-font-semibold nx-text-primary-800 dark:nx-bg-primary-400/10 dark:nx-text-primary-600 contrast-more:nx-border-primary-500 contrast-more:dark:nx-border-primary-500" href="/packages/jest-environment">@edge-runtime/jest-environment</a></li><li class="nx-flex nx-flex-col nx-gap-1"><a class="nx-flex nx-rounded nx-px-2 nx-py-1.5 nx-text-sm nx-transition-colors [word-break:break-word] nx-cursor-pointer [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] contrast-more:nx-border nx-text-gray-500 hover:nx-bg-gray-100 hover:nx-text-gray-900 dark:nx-text-neutral-400 dark:hover:nx-bg-primary-100/5 dark:hover:nx-text-gray-50 contrast-more:nx-text-gray-900 contrast-more:dark:nx-text-gray-50 contrast-more:nx-border-transparent contrast-more:hover:nx-border-gray-900 contrast-more:dark:hover:nx-border-gray-50" href="/packages/jest-expect">@edge-runtime/jest-expect</a></li><li class="nx-flex nx-flex-col nx-gap-1"><a class="nx-flex nx-rounded nx-px-2 nx-py-1.5 nx-text-sm nx-transition-colors [word-break:break-word] nx-cursor-pointer [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] contrast-more:nx-border nx-text-gray-500 hover:nx-bg-gray-100 hover:nx-text-gray-900 dark:nx-text-neutral-400 dark:hover:nx-bg-primary-100/5 dark:hover:nx-text-gray-50 contrast-more:nx-text-gray-900 contrast-more:dark:nx-text-gray-50 contrast-more:nx-border-transparent contrast-more:hover:nx-border-gray-900 contrast-more:dark:hover:nx-border-gray-50" href="/packages/node-utils">@edge-runtime/node-utils</a></li><li class="nx-flex nx-flex-col nx-gap-1"><a class="nx-flex nx-rounded nx-px-2 nx-py-1.5 nx-text-sm nx-transition-colors [word-break:break-word] nx-cursor-pointer [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] contrast-more:nx-border nx-text-gray-500 hover:nx-bg-gray-100 hover:nx-text-gray-900 dark:nx-text-neutral-400 dark:hover:nx-bg-primary-100/5 dark:hover:nx-text-gray-50 contrast-more:nx-text-gray-900 contrast-more:dark:nx-text-gray-50 contrast-more:nx-border-transparent contrast-more:hover:nx-border-gray-900 contrast-more:dark:hover:nx-border-gray-50" href="/packages/ponyfill">@edge-runtime/ponyfill</a></li><li class="nx-flex nx-flex-col nx-gap-1"><a class="nx-flex nx-rounded nx-px-2 nx-py-1.5 nx-text-sm nx-transition-colors [word-break:break-word] nx-cursor-pointer [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] contrast-more:nx-border nx-text-gray-500 hover:nx-bg-gray-100 hover:nx-text-gray-900 dark:nx-text-neutral-400 dark:hover:nx-bg-primary-100/5 dark:hover:nx-text-gray-50 contrast-more:nx-text-gray-900 contrast-more:dark:nx-text-gray-50 contrast-more:nx-border-transparent contrast-more:hover:nx-border-gray-900 contrast-more:dark:hover:nx-border-gray-50" href="/packages/primitives">@edge-runtime/primitives</a></li><li class="nx-flex nx-flex-col nx-gap-1"><a class="nx-flex nx-rounded nx-px-2 nx-py-1.5 nx-text-sm nx-transition-colors [word-break:break-word] nx-cursor-pointer [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] contrast-more:nx-border nx-text-gray-500 hover:nx-bg-gray-100 hover:nx-text-gray-900 dark:nx-text-neutral-400 dark:hover:nx-bg-primary-100/5 dark:hover:nx-text-gray-50 contrast-more:nx-text-gray-900 contrast-more:dark:nx-text-gray-50 contrast-more:nx-border-transparent contrast-more:hover:nx-border-gray-900 contrast-more:dark:hover:nx-border-gray-50" href="/packages/runtime">edge-runtime</a></li><li class="nx-flex nx-flex-col nx-gap-1"><a class="nx-flex nx-rounded nx-px-2 nx-py-1.5 nx-text-sm nx-transition-colors [word-break:break-word] nx-cursor-pointer [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] contrast-more:nx-border nx-text-gray-500 hover:nx-bg-gray-100 hover:nx-text-gray-900 dark:nx-text-neutral-400 dark:hover:nx-bg-primary-100/5 dark:hover:nx-text-gray-50 contrast-more:nx-text-gray-900 contrast-more:dark:nx-text-gray-50 contrast-more:nx-border-transparent contrast-more:hover:nx-border-gray-900 contrast-more:dark:hover:nx-border-gray-50" href="/packages/types">@edge-runtime/types</a></li><li class="nx-flex nx-flex-col nx-gap-1"><a class="nx-flex nx-rounded nx-px-2 nx-py-1.5 nx-text-sm nx-transition-colors [word-break:break-word] nx-cursor-pointer [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] contrast-more:nx-border nx-text-gray-500 hover:nx-bg-gray-100 hover:nx-text-gray-900 dark:nx-text-neutral-400 dark:hover:nx-bg-primary-100/5 dark:hover:nx-text-gray-50 contrast-more:nx-text-gray-900 contrast-more:dark:nx-text-gray-50 contrast-more:nx-border-transparent contrast-more:hover:nx-border-gray-900 contrast-more:dark:hover:nx-border-gray-50" href="/packages/user-agent">@edge-runtime/user-agent</a></li><li class="nx-flex nx-flex-col nx-gap-1"><a class="nx-flex nx-rounded nx-px-2 nx-py-1.5 nx-text-sm nx-transition-colors [word-break:break-word] nx-cursor-pointer [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] contrast-more:nx-border nx-text-gray-500 hover:nx-bg-gray-100 hover:nx-text-gray-900 dark:nx-text-neutral-400 dark:hover:nx-bg-primary-100/5 dark:hover:nx-text-gray-50 contrast-more:nx-text-gray-900 contrast-more:dark:nx-text-gray-50 contrast-more:nx-border-transparent contrast-more:hover:nx-border-gray-900 contrast-more:dark:hover:nx-border-gray-50" href="/packages/vm">@edge-runtime/vm</a></li></ul></div></div></li><li class="nx-flex nx-flex-col nx-gap-1"><a href="https://github.com/vercel/edge-runtime/releases" target="_blank" rel="noreferrer" class="nx-flex nx-rounded nx-px-2 nx-py-1.5 nx-text-sm nx-transition-colors [word-break:break-word] nx-cursor-pointer [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] contrast-more:nx-border nx-text-gray-500 hover:nx-bg-gray-100 hover:nx-text-gray-900 dark:nx-text-neutral-400 dark:hover:nx-bg-primary-100/5 dark:hover:nx-text-gray-50 contrast-more:nx-text-gray-900 contrast-more:dark:nx-text-gray-50 contrast-more:nx-border-transparent contrast-more:hover:nx-border-gray-900 contrast-more:dark:hover:nx-border-gray-50">Changelog<span class="nx-sr-only nx-select-none"> (opens in a new tab)</span></a></li></ul></div></div></div><div class="nx-sticky nx-bottom-0 nx-bg-white dark:nx-bg-dark 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Give us feedback →<span class="nx-sr-only nx-select-none"> (opens in a new tab)</span></a><a class="nx-text-xs nx-font-medium nx-text-gray-500 hover:nx-text-gray-900 dark:nx-text-gray-400 dark:hover:nx-text-gray-100 contrast-more:nx-text-gray-800 contrast-more:dark:nx-text-gray-50" href="https://github.com/vercel/edge-runtime/blob/main/docs/pages/packages/jest-environment.mdx">Edit this page on GitHub</a></div></div></nav><div id="reach-skip-nav"></div><article class="nx-w-full nx-break-words nextra-content nx-flex nx-min-h-[calc(100vh-var(--nextra-navbar-height))] nx-min-w-0 nx-justify-center nx-pb-8 nx-pr-[calc(env(safe-area-inset-right)-1.5rem)]"><main class="nx-w-full nx-min-w-0 nx-max-w-6xl nx-px-6 nx-pt-4 md:nx-px-12"><div class="nextra-breadcrumb nx-mt-1.5 nx-flex nx-items-center nx-gap-1 nx-overflow-hidden nx-text-sm nx-text-gray-500 dark:nx-text-gray-400 contrast-more:nx-text-current"><div class="nx-whitespace-nowrap nx-transition-colors nx-min-w-[24px] nx-overflow-hidden 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a new tab)</span></a> tests against the Edge Runtime environment.</p> <p class="nx-mt-6 nx-leading-7 first:nx-mt-0">It helps you to write tests assertion without being worried about the environment setup.</p> <h2 class="nx-font-semibold nx-tracking-tight nx-text-slate-900 dark:nx-text-slate-100 nx-mt-10 nx-border-b nx-pb-1 nx-text-3xl nx-border-neutral-200/70 contrast-more:nx-border-neutral-400 dark:nx-border-primary-100/10 contrast-more:dark:nx-border-neutral-400">Installation<a href="#installation" id="installation" class="subheading-anchor" aria-label="Permalink for this section"></a></h2> <button type="button" aria-hidden="true" style="position:fixed;top:1px;left:1px;width:1px;height:0;padding:0;margin:-1px;overflow:hidden;clip:rect(0, 0, 0, 0);white-space:nowrap;border-width:0"></button><div class="nextra-scrollbar nx-overflow-x-auto nx-overflow-y-hidden nx-overscroll-x-contain"><div class="nx-mt-4 nx-flex nx-w-max nx-min-w-full nx-border-b nx-border-gray-200 nx-pb-px dark:nx-border-neutral-800" role="tablist" aria-orientation="horizontal"><button class="nx-mr-2 nx-rounded-t nx-p-2 nx-font-medium nx-leading-5 nx-transition-colors -nx-mb-0.5 nx-select-none nx-border-b-2 nx-border-primary-500 nx-text-primary-600" id="headlessui-tabs-tab-:R1ciqb6:" role="tab" type="button" aria-selected="true" tabindex="0" data-headlessui-state="selected">npm</button><button class="nx-mr-2 nx-rounded-t nx-p-2 nx-font-medium nx-leading-5 nx-transition-colors -nx-mb-0.5 nx-select-none nx-border-b-2 nx-border-transparent nx-text-gray-600 hover:nx-border-gray-200 hover:nx-text-black dark:nx-text-gray-200 dark:hover:nx-border-neutral-800 dark:hover:nx-text-white" id="headlessui-tabs-tab-:R2ciqb6:" role="tab" type="button" aria-selected="false" tabindex="-1" data-headlessui-state="">pnpm</button><button class="nx-mr-2 nx-rounded-t nx-p-2 nx-font-medium nx-leading-5 nx-transition-colors -nx-mb-0.5 nx-select-none nx-border-b-2 nx-border-transparent nx-text-gray-600 hover:nx-border-gray-200 hover:nx-text-black dark:nx-text-gray-200 dark:hover:nx-border-neutral-800 dark:hover:nx-text-white" id="headlessui-tabs-tab-:R3ciqb6:" role="tab" type="button" aria-selected="false" tabindex="-1" data-headlessui-state="">yarn</button><button class="nx-mr-2 nx-rounded-t nx-p-2 nx-font-medium nx-leading-5 nx-transition-colors -nx-mb-0.5 nx-select-none nx-border-b-2 nx-border-transparent nx-text-gray-600 hover:nx-border-gray-200 hover:nx-text-black dark:nx-text-gray-200 dark:hover:nx-border-neutral-800 dark:hover:nx-text-white" id="headlessui-tabs-tab-:R4ciqb6:" role="tab" type="button" aria-selected="false" tabindex="-1" data-headlessui-state="">bun</button></div></div><div><div class="nx-rounded nx-pt-6" id="headlessui-tabs-panel-:R1kiqb6:" role="tabpanel" tabindex="0" data-headlessui-state="selected"><div class="nextra-code-block nx-relative nx-mt-6 first:nx-mt-0"><pre class="nx-bg-primary-700/5 nx-mb-4 nx-overflow-x-auto nx-rounded-xl nx-subpixel-antialiased dark:nx-bg-primary-300/10 nx-text-[.9em] contrast-more:nx-border contrast-more:nx-border-primary-900/20 contrast-more:nx-contrast-150 contrast-more:dark:nx-border-primary-100/40 nx-py-4" data-language="sh" data-theme="default"><code class="nx-border-black nx-border-opacity-[0.04] nx-bg-opacity-[0.03] nx-bg-black nx-break-words nx-rounded-md nx-border nx-py-0.5 nx-px-[.25em] nx-text-[.9em] dark:nx-border-white/10 dark:nx-bg-white/10" dir="ltr" data-language="sh" data-theme="default"><span class="line"><span style="color:var(--shiki-token-function)">npm</span><span style="color:var(--shiki-color-text)"> </span><span style="color:var(--shiki-token-string)">install</span><span style="color:var(--shiki-color-text)"> </span><span style="color:var(--shiki-token-string)">@edge-runtime/jest-environment</span></span></code></pre><div class="nx-opacity-0 nx-transition [div:hover>&]:nx-opacity-100 focus-within:nx-opacity-100 nx-flex nx-gap-1 nx-absolute nx-m-[11px] nx-right-0 nx-top-0"><button class="nextra-button nx-transition-all active:nx-opacity-50 nx-bg-primary-700/5 nx-border nx-border-black/5 nx-text-gray-600 hover:nx-text-gray-900 nx-rounded-md nx-p-1.5 dark:nx-bg-primary-300/10 dark:nx-border-white/10 dark:nx-text-gray-400 dark:hover:nx-text-gray-50 md:nx-hidden" title="Toggle word wrap"><svg viewBox="0 0 24 24" width="24" height="24" class="nx-pointer-events-none nx-h-4 nx-w-4"><path fill="currentColor" d="M4 19h6v-2H4v2zM20 5H4v2h16V5zm-3 6H4v2h13.25c1.1 0 2 .9 2 2s-.9 2-2 2H15v-2l-3 3l3 3v-2h2c2.21 0 4-1.79 4-4s-1.79-4-4-4z"></path></svg></button><button class="nextra-button nx-transition-all active:nx-opacity-50 nx-bg-primary-700/5 nx-border nx-border-black/5 nx-text-gray-600 hover:nx-text-gray-900 nx-rounded-md nx-p-1.5 dark:nx-bg-primary-300/10 dark:nx-border-white/10 dark:nx-text-gray-400 dark:hover:nx-text-gray-50" title="Copy code" tabindex="0"><svg width="24" height="24" viewBox="0 0 24 24" fill="none" xmlns="http://www.w3.org/2000/svg" stroke="currentColor" class="nextra-copy-icon nx-pointer-events-none nx-h-4 nx-w-4"><rect x="9" y="9" width="13" height="13" rx="2" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"></rect><path d="M5 15H4C2.89543 15 2 14.1046 2 13V4C2 2.89543 2.89543 2 4 2H13C14.1046 2 15 2.89543 15 4V5" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"></path></svg></button></div></div></div><span aria-hidden="true" id="headlessui-tabs-panel-:R2kiqb6:" role="tabpanel" tabindex="-1" style="position:fixed;top:1px;left:1px;width:1px;height:0;padding:0;margin:-1px;overflow:hidden;clip:rect(0, 0, 0, 0);white-space:nowrap;border-width:0"></span><span aria-hidden="true" id="headlessui-tabs-panel-:R3kiqb6:" role="tabpanel" tabindex="-1" style="position:fixed;top:1px;left:1px;width:1px;height:0;padding:0;margin:-1px;overflow:hidden;clip:rect(0, 0, 0, 0);white-space:nowrap;border-width:0"></span><span aria-hidden="true" id="headlessui-tabs-panel-:R4kiqb6:" role="tabpanel" tabindex="-1" style="position:fixed;top:1px;left:1px;width:1px;height:0;padding:0;margin:-1px;overflow:hidden;clip:rect(0, 0, 0, 0);white-space:nowrap;border-width:0"></span></div> <h2 class="nx-font-semibold nx-tracking-tight nx-text-slate-900 dark:nx-text-slate-100 nx-mt-10 nx-border-b nx-pb-1 nx-text-3xl nx-border-neutral-200/70 contrast-more:nx-border-neutral-400 dark:nx-border-primary-100/10 contrast-more:dark:nx-border-neutral-400">Usage<a href="#usage" id="usage" class="subheading-anchor" aria-label="Permalink for this section"></a></h2> <p class="nx-mt-6 nx-leading-7 first:nx-mt-0">Jest enables you to define the test environment through a <a href="https://jestjs.io/docs/configuration#testenvironment-string" target="_blank" rel="noreferrer" class="nx-text-primary-600 nx-underline nx-decoration-from-font [text-underline-position:from-font]">code comment<span class="nx-sr-only nx-select-none"> (opens in a new tab)</span></a> or as a <a href="https://jestjs.io/docs/cli#--envenvironment" target="_blank" rel="noreferrer" class="nx-text-primary-600 nx-underline nx-decoration-from-font [text-underline-position:from-font]">CLI option<span class="nx-sr-only nx-select-none"> (opens in a new tab)</span></a>.</p> <p class="nx-mt-6 nx-leading-7 first:nx-mt-0">For example, the following test would <strong>pass</strong>:</p> <div class="nextra-code-block nx-relative nx-mt-6 first:nx-mt-0"><pre class="nx-bg-primary-700/5 nx-mb-4 nx-overflow-x-auto nx-rounded-xl nx-subpixel-antialiased dark:nx-bg-primary-300/10 nx-text-[.9em] contrast-more:nx-border contrast-more:nx-border-primary-900/20 contrast-more:nx-contrast-150 contrast-more:dark:nx-border-primary-100/40 nx-py-4" data-language="js" data-theme="default"><code class="nx-border-black nx-border-opacity-[0.04] nx-bg-opacity-[0.03] nx-bg-black nx-break-words nx-rounded-md nx-border nx-py-0.5 nx-px-[.25em] nx-text-[.9em] dark:nx-border-white/10 dark:nx-bg-white/10" dir="ltr" data-language="js" data-theme="default"><span class="line"><span style="color:var(--shiki-token-comment)">// jest --env node</span></span> <span class="line"><span style="color:var(--shiki-token-comment)">// ✅ Pass</span></span> <span class="line"><span style="color:var(--shiki-token-function)">it</span><span style="color:var(--shiki-color-text)">(</span><span style="color:var(--shiki-token-string-expression)">'should return the correct value'</span><span style="color:var(--shiki-token-punctuation)">,</span><span style="color:var(--shiki-color-text)"> () </span><span style="color:var(--shiki-token-keyword)">=></span><span style="color:var(--shiki-color-text)"> {</span></span> <span class="line"><span style="color:var(--shiki-color-text)"> </span><span style="color:var(--shiki-token-keyword)">let</span><span style="color:var(--shiki-color-text)"> val </span><span style="color:var(--shiki-token-keyword)">=</span><span style="color:var(--shiki-color-text)"> </span><span style="color:var(--shiki-token-function)">eval</span><span style="color:var(--shiki-color-text)">(</span><span style="color:var(--shiki-token-string-expression)">'2 + 2'</span><span style="color:var(--shiki-color-text)">)</span></span> <span class="line"><span style="color:var(--shiki-color-text)"> </span><span style="color:var(--shiki-token-function)">expect</span><span style="color:var(--shiki-color-text)">(val)</span><span style="color:var(--shiki-token-function)">.toBe</span><span style="color:var(--shiki-color-text)">(</span><span style="color:var(--shiki-token-constant)">4</span><span style="color:var(--shiki-color-text)">)</span></span> <span class="line"><span style="color:var(--shiki-color-text)">})</span></span></code></pre><div class="nx-opacity-0 nx-transition [div:hover>&]:nx-opacity-100 focus-within:nx-opacity-100 nx-flex nx-gap-1 nx-absolute nx-m-[11px] nx-right-0 nx-top-0"><button class="nextra-button nx-transition-all active:nx-opacity-50 nx-bg-primary-700/5 nx-border nx-border-black/5 nx-text-gray-600 hover:nx-text-gray-900 nx-rounded-md nx-p-1.5 dark:nx-bg-primary-300/10 dark:nx-border-white/10 dark:nx-text-gray-400 dark:hover:nx-text-gray-50 md:nx-hidden" title="Toggle word wrap"><svg viewBox="0 0 24 24" width="24" height="24" class="nx-pointer-events-none nx-h-4 nx-w-4"><path fill="currentColor" d="M4 19h6v-2H4v2zM20 5H4v2h16V5zm-3 6H4v2h13.25c1.1 0 2 .9 2 2s-.9 2-2 2H15v-2l-3 3l3 3v-2h2c2.21 0 4-1.79 4-4s-1.79-4-4-4z"></path></svg></button><button class="nextra-button nx-transition-all active:nx-opacity-50 nx-bg-primary-700/5 nx-border nx-border-black/5 nx-text-gray-600 hover:nx-text-gray-900 nx-rounded-md nx-p-1.5 dark:nx-bg-primary-300/10 dark:nx-border-white/10 dark:nx-text-gray-400 dark:hover:nx-text-gray-50" title="Copy code" tabindex="0"><svg width="24" height="24" viewBox="0 0 24 24" fill="none" xmlns="http://www.w3.org/2000/svg" stroke="currentColor" class="nextra-copy-icon nx-pointer-events-none nx-h-4 nx-w-4"><rect x="9" y="9" width="13" height="13" rx="2" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"></rect><path d="M5 15H4C2.89543 15 2 14.1046 2 13V4C2 2.89543 2.89543 2 4 2H13C14.1046 2 15 2.89543 15 4V5" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"></path></svg></button></div></div> <p class="nx-mt-6 nx-leading-7 first:nx-mt-0">The following test would <strong>fail</strong> when using the Edge Runtime:</p> <div class="nextra-code-block nx-relative nx-mt-6 first:nx-mt-0"><pre class="nx-bg-primary-700/5 nx-mb-4 nx-overflow-x-auto nx-rounded-xl nx-subpixel-antialiased dark:nx-bg-primary-300/10 nx-text-[.9em] contrast-more:nx-border contrast-more:nx-border-primary-900/20 contrast-more:nx-contrast-150 contrast-more:dark:nx-border-primary-100/40 nx-py-4" data-language="js" data-theme="default"><code class="nx-border-black nx-border-opacity-[0.04] nx-bg-opacity-[0.03] nx-bg-black nx-break-words nx-rounded-md nx-border nx-py-0.5 nx-px-[.25em] nx-text-[.9em] dark:nx-border-white/10 dark:nx-bg-white/10" dir="ltr" data-language="js" data-theme="default"><span class="line"><span style="color:var(--shiki-token-comment)">// jest --env @edge-runtime/jest-environment</span></span> <span class="line"><span style="color:var(--shiki-token-comment)">// ❌ Fail</span></span> <span class="line"><span style="color:var(--shiki-token-comment)">// Error name: "EvalError"</span></span> <span class="line"><span style="color:var(--shiki-token-comment)">// Error message: "Code generation from strings disallowed for this context"</span></span> <span class="line"><span style="color:var(--shiki-token-function)">it</span><span style="color:var(--shiki-color-text)">(</span><span style="color:var(--shiki-token-string-expression)">'should return the correct value'</span><span style="color:var(--shiki-token-punctuation)">,</span><span style="color:var(--shiki-color-text)"> () </span><span style="color:var(--shiki-token-keyword)">=></span><span style="color:var(--shiki-color-text)"> {</span></span> <span class="line"><span style="color:var(--shiki-color-text)"> </span><span style="color:var(--shiki-token-keyword)">let</span><span style="color:var(--shiki-color-text)"> val </span><span style="color:var(--shiki-token-keyword)">=</span><span style="color:var(--shiki-color-text)"> </span><span style="color:var(--shiki-token-function)">eval</span><span style="color:var(--shiki-color-text)">(</span><span style="color:var(--shiki-token-string-expression)">'2 + 2'</span><span style="color:var(--shiki-color-text)">)</span></span> <span class="line"><span style="color:var(--shiki-color-text)"> </span><span style="color:var(--shiki-token-function)">expect</span><span style="color:var(--shiki-color-text)">(val)</span><span style="color:var(--shiki-token-function)">.toBe</span><span style="color:var(--shiki-color-text)">(</span><span style="color:var(--shiki-token-constant)">4</span><span style="color:var(--shiki-color-text)">)</span></span> <span class="line"><span style="color:var(--shiki-color-text)">})</span></span></code></pre><div class="nx-opacity-0 nx-transition [div:hover>&]:nx-opacity-100 focus-within:nx-opacity-100 nx-flex nx-gap-1 nx-absolute nx-m-[11px] nx-right-0 nx-top-0"><button class="nextra-button nx-transition-all active:nx-opacity-50 nx-bg-primary-700/5 nx-border nx-border-black/5 nx-text-gray-600 hover:nx-text-gray-900 nx-rounded-md nx-p-1.5 dark:nx-bg-primary-300/10 dark:nx-border-white/10 dark:nx-text-gray-400 dark:hover:nx-text-gray-50 md:nx-hidden" title="Toggle word wrap"><svg viewBox="0 0 24 24" width="24" height="24" class="nx-pointer-events-none nx-h-4 nx-w-4"><path fill="currentColor" d="M4 19h6v-2H4v2zM20 5H4v2h16V5zm-3 6H4v2h13.25c1.1 0 2 .9 2 2s-.9 2-2 2H15v-2l-3 3l3 3v-2h2c2.21 0 4-1.79 4-4s-1.79-4-4-4z"></path></svg></button><button class="nextra-button nx-transition-all active:nx-opacity-50 nx-bg-primary-700/5 nx-border nx-border-black/5 nx-text-gray-600 hover:nx-text-gray-900 nx-rounded-md nx-p-1.5 dark:nx-bg-primary-300/10 dark:nx-border-white/10 dark:nx-text-gray-400 dark:hover:nx-text-gray-50" title="Copy code" tabindex="0"><svg width="24" height="24" viewBox="0 0 24 24" fill="none" xmlns="http://www.w3.org/2000/svg" stroke="currentColor" class="nextra-copy-icon nx-pointer-events-none nx-h-4 nx-w-4"><rect x="9" y="9" width="13" height="13" rx="2" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"></rect><path d="M5 15H4C2.89543 15 2 14.1046 2 13V4C2 2.89543 2.89543 2 4 2H13C14.1046 2 15 2.89543 15 4V5" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"></path></svg></button></div></div><div class="nx-mt-16"></div><div class="nx-mb-8 nx-flex nx-items-center nx-border-t nx-pt-8 dark:nx-border-neutral-800 contrast-more:nx-border-neutral-400 dark:contrast-more:nx-border-neutral-400 print:nx-hidden"><a title="@edge-runtime/format" class="nx-flex nx-max-w-[50%] nx-items-center 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