Prevent window access in useViewportSize when server rendered (#2468

)

* Add SSR check on window call

* Handle client render after server using state

* Add changeset

* Lint

* Add testing renderHookServer

* Remove unused

* Update changeset

* Lint

* useIsSsr to useSsrCheck

* Lint

* Update viewport hook

* Add R17 version

* Revert R17 package changes

* CR changes

* Lint

* Is it that simple?

* Semi shot in the dark

* Revert "Semi shot in the dark"

This reverts commit d8b5fed.

* Bump changesets to minor

.changeset/mighty-clouds-impress.md

@@ -0,0 +1,15 @@
+---
+'@leafygreen-ui/testing-lib': minor
+---
+
+Adds `renderHookServer` method
+
+@testing-library/react-hooks/server exposed a `renderHook` method
+that allowed for one to render hooks as if SSR, and control
+hydration. This is no longer supported in versions >=18.
+
+This code was extracted from @testing-library/react-hooks/server and
+updated to be compatible with React version >= 18 using `hydrateRoot`.
+
+More context found here:
+https://github.com/testing-library/react-testing-library/issues/1120

.changeset/short-eels-deliver.md

@@ -0,0 +1,7 @@
+---
+'@leafygreen-ui/hooks': minor
+---
+
+Adds `useSsrCheck` and adds it to viewport check in `useViewportSize`.
+
+When server side rendering is used, `window` is not defined. This is causing build issues on the server where we access `window` in `useViewportSize`. To fix this, this change adds a hook, `useSsrCheck`, that checks the rendering environment and can be used before attempting to access `window`. It adds a check of this to `useViewportSize` to fix the current build issue.

packages/hooks/src/hooks.spec.tsx

@@ -1,13 +1,14 @@
 import { waitFor } from '@testing-library/react';
 
-import { act, renderHook } from '@leafygreen-ui/testing-lib';
+import { act, renderHook, renderHookServer } from '@leafygreen-ui/testing-lib';
 
 import {
   useEventListener,
   useIdAllocator,
   useObjectDependency,
   usePoller,
   usePrevious,
+  useSsrCheck,
   useViewportSize,
 } from './index';
 import useValidation from './useValidation';
@@ -353,7 +354,7 @@ describe('packages/hooks', () => {
   });
 
   describe('useValidation', () => {
-    it('Returns validation functions when callback is defined', () => {
+    test('Returns validation functions when callback is defined', () => {
       const { result } = renderHook(() =>
         // eslint-disable-next-line no-console
         useValidation(value => console.log(value)),
@@ -362,10 +363,19 @@ describe('packages/hooks', () => {
       expect(result.current.onChange).toBeDefined();
     });
 
-    it('Returns validation functions when callback is undefined', () => {
+    test('Returns validation functions when callback is undefined', () => {
       const { result } = renderHook(() => useValidation());
       expect(result.current.onBlur).toBeDefined();
       expect(result.current.onChange).toBeDefined();
     });
   });
+
+  describe('useSsrCheck', () => {
+    test('should return true when server-side rendered and false after hydration', () => {
+      const { result, hydrate } = renderHookServer(useSsrCheck);
+      expect(result.current).toBe(true);
+      hydrate();
+      expect(result.current).toBe(false);
+    });
+  });
 });

packages/hooks/src/index.ts

@@ -13,6 +13,7 @@ export { default as useMutationObserver } from './useMutationObserver';
 export { default as useObjectDependency } from './useObjectDependency';
 export { default as usePoller } from './usePoller';
 export { default as usePrevious } from './usePrevious';
+export { default as useSsrCheck } from './useSsrCheck';
 export { useStateRef } from './useStateRef';
 export { default as useValidation } from './useValidation';
 export { default as useViewportSize } from './useViewportSize';

packages/hooks/src/useSsrCheck.ts

@@ -0,0 +1,15 @@
+import { useEffect, useState } from 'react';
+
+export default function useSsrCheck() {
+  const [isSsr, setIsSsr] = useState(typeof window === 'undefined');
+
+  useEffect(() => {
+    // When rendered on server, this won't run until we're on the client. Therefore,
+    // isSsr should be true when server rendered, and only be set to false on subsequent client render.
+    // When rendered directly on the client, isSsr should already be false, so
+    // this update shouldn't trigger a re-render.
+    setIsSsr(false);
+  }, []);
+
+  return isSsr;
+}

packages/hooks/src/useViewportSize.ts

@@ -1,6 +1,8 @@
 import { useEffect, useState } from 'react';
 import debounce from 'lodash/debounce';
 
+import useSsrCheck from './useSsrCheck';
+
 interface ViewportSize {
   width: number;
   height: number;
@@ -13,9 +15,11 @@ function getViewportSize(): ViewportSize {
   };
 }
 
-export default function useViewportSize(): ViewportSize {
-  const [viewportSize, setViewportUpdateVal] = useState<ViewportSize>(
-    getViewportSize(),
+export default function useViewportSize(): ViewportSize | null {
+  const isSsr = useSsrCheck();
+
+  const [viewportSize, setViewportUpdateVal] = useState<ViewportSize | null>(
+    isSsr ? null : getViewportSize(), // window undefined on server
   );
 
   useEffect(() => {
@@ -24,8 +28,8 @@ export default function useViewportSize(): ViewportSize {
       100,
     );
 
+    // useEffect callback only runs on client, so safe to assume window is defined here
     window.addEventListener('resize', calcResize);
-
     return () => window.removeEventListener('resize', calcResize);
   }, []);
 

packages/testing-lib/rollup.config.mjs

@@ -0,0 +1,18 @@
+import { esmConfig, umdConfig } from '@lg-tools/build/config/rollup.config.mjs';
+
+export default [
+  esmConfig,
+  umdConfig,
+  {
+    ...esmConfig,
+    input: ['./src/renderHookServer.tsx', './src/renderHookServerV17.tsx'],
+    output: {
+      // cjs is fully supported in node.js
+      format: 'cjs', // overrides esm format from esmConfig.output
+      entryFileNames: '[name].js',
+      dir: 'dist',
+      preserveModules: true,
+      exports: 'auto',
+    },
+  },
+];

packages/testing-lib/src/RTLOverrides.ts

@@ -1,4 +1,11 @@
+import * as React from 'react';
 import * as RTL from '@testing-library/react';
+import path from 'path';
+
+import {
+  RenderHookServerOptions,
+  RenderHookServerResult,
+} from './renderHookServer';
 
 /**
  * Utility type that returns `X.Y` if it exists, otherwise defaults to fallback type `Z`, or `any`
@@ -34,3 +41,16 @@ export const act: Exists<typeof RTL, 'act'> =
     const RHTL = require('@testing-library/react-hooks');
     return RHTL.act;
   })();
+
+/**
+ * Correct `renderHookServer` method based on React version.
+ */
+export const renderHookServer: <Hook extends () => any>(
+  useHook: Hook,
+  options?: RenderHookServerOptions,
+) => RenderHookServerResult<Hook> = (() => {
+  const isReact18 = parseInt(React.version.split('.')[0], 10) >= 18;
+  const filename = isReact18 ? 'renderHookServer' : 'renderHookServerV17';
+  const RHS = require(path.resolve(__dirname, filename));
+  return RHS.renderHookServer;
+})();

packages/testing-lib/src/index.ts

@@ -1,7 +1,7 @@
 import * as Context from './context';
 import * as jest from './jest';
 import * as JestDOM from './jest-dom';
-export { act, renderHook } from './RTLOverrides';
+export { act, renderHook, renderHookServer } from './RTLOverrides';
 export { useTraceUpdate } from './useTraceUpdate';
 export { waitForState } from './waitForState';
 export { waitForTransition } from './waitForTransition';

packages/testing-lib/src/renderHookServer.tsx

@@ -0,0 +1,94 @@
+import type { ReactNode } from 'react';
+import React from 'react';
+//@ts-ignore Cannot find module 'react-dom/client' or its corresponding type declarations
+import { hydrateRoot } from 'react-dom/client';
+import { renderToString } from 'react-dom/server';
+import { act } from 'react-dom/test-utils';
+
+export interface RenderHookServerOptions {
+  wrapper?: ({ children }: { children: ReactNode }) => JSX.Element;
+}
+
+export interface RenderHookServerResult<Hook extends () => any> {
+  result: { current: ReturnType<Hook> };
+  hydrate: () => void;
+}
+
+/**
+ * Allows you to mock the server side rendering of a hook.
+ *
+ * @testing-library/react-hooks/server exposed a `renderHook` method
+ * that allowed for one to render hooks as if SSR, and control
+ * hydration. This is no longer supported in versions >=18.
+ *
+ * This code was extracted from @testing-library/react-hooks/server and
+ * updated to be compatible with React version >= 18 using `hydrateRoot`.
+ *
+ * More context found here:
+ * https://github.com/testing-library/react-testing-library/issues/1120
+ *
+ * e.g.
+ * ```typescript
+ *   it('should return true when server-side rendered and false after hydration', () => {
+ *     const { result, hydrate } = renderHookServer(useMyHook);
+ *     expect(result.current).toBe(true);
+ *     hydrate();
+ *     expect(result.current).toBe(false);
+ *   });
+ * ```
+}
+ */
+export function renderHookServer<Hook extends () => any>(
+  useHook: Hook,
+  { wrapper: Wrapper }: RenderHookServerOptions = {},
+): RenderHookServerResult<Hook> {
+  // Store hook return value
+  const results: Array<ReturnType<Hook>> = [];
+  const result = {
+    get current() {
+      return results.slice(-1)[0];
+    },
+  };
+
+  // Test component to render hook in
+  const Component = ({ useHook }: { useHook: Hook }) => {
+    results.push(useHook());
+    return null;
+  };
+
+  // Add wrapper if necessary
+  const component = Wrapper ? (
+    <Wrapper>
+      <Component useHook={useHook} />
+    </Wrapper>
+  ) : (
+    <Component useHook={useHook} />
+  );
+
+  // Running tests in an environment that simulates a browser (like Jest with jsdom),
+  // the window object will still be available even when server rendered. To ensure
+  // that window is not available during SSR we need to explicitly mock or remove the
+  // window object.
+  // @ts-ignore Type 'undefined' is not assignable to type 'Window'.
+  jest.spyOn(global, 'window', 'get').mockImplementation(() => undefined);
+
+  // Render hook on server
+  const serverOutput = renderToString(component);
+
+  // Restore window
+  jest.spyOn(global, 'window', 'get').mockRestore();
+
+  // Render hook on client
+  const hydrate = () => {
+    const root = document.createElement('div');
+    root.innerHTML = serverOutput;
+    act(() => {
+      hydrateRoot(root, component);
+    });
+  };
+
+  return {
+    result,
+    hydrate,
+  };
+}

packages/testing-lib/src/renderHookServerV17.tsx

@@ -0,0 +1,32 @@
+import { renderHook } from '@testing-library/react-hooks/server';
+
+import {
+  RenderHookServerOptions,
+  RenderHookServerResult,
+} from './renderHookServer';
+
+/**
+ * Allows you to mock the server side rendering of a hook in pre React 18 versions.
+ * For versions >=18, use `@testing-lib/renderHookServer`.
+ *
+ * e.g.
+ * ```typescript
+ *   it('should return true when server-side rendered and false after hydration', () => {
+ *     const { result, hydrate } = renderHookServer(useMyHook);
+ *     expect(result.current).toBe(true);
+ *     hydrate();
+ *     expect(result.current).toBe(false);
+ *   });
+ * ```
+}
+ */
+export function renderHookServer<Hook extends () => any>(
+  useHook: Hook,
+  { wrapper }: RenderHookServerOptions = {},
+): RenderHookServerResult<Hook> {
+  // @ts-ignore Type 'undefined' is not assignable to type 'Window'.
+  jest.spyOn(global, 'window', 'get').mockImplementation(() => undefined);
+  const response = renderHook(useHook, { wrapper });
+  jest.spyOn(global, 'window', 'get').mockRestore();
+  return response;
+}