basic matcher tests

Author: phryneas

src/jest/__tests__/renderStreamMatchers.test.tsx

@@ -0,0 +1,70 @@
+/* eslint-disable @typescript-eslint/no-unnecessary-condition */
+import {EventEmitter} from 'node:events'
+import {describe, test, expect} from '@jest/globals'
+import {createRenderStream} from '@testing-library/react-render-stream'
+import * as React from 'react'
+import {
+  RenderStreamMatchers,
+  toRenderExactlyTimes,
+  toRerender,
+} from '../renderStreamMatchers.js'
+
+expect.extend({
+  toRerender,
+  toRenderExactlyTimes,
+})
+
+declare module 'expect' {
+  // eslint-disable-next-line @typescript-eslint/no-empty-interface
+  interface Matchers<R extends void | Promise<void>, T = unknown>
+    extends RenderStreamMatchers<R, T> {}
+}
+
+const testEvents = new EventEmitter<{
+  rerender: []
+}>()
+
+function RerenderingComponent() {
+  const [, rerender] = React.useReducer(c => c + 1, 0)
+  React.useEffect(() => {
+    function cb() {
+      const anyThis = globalThis as any as {IS_REACT_ACT_ENVIRONMENT?: boolean}
+      const prev = anyThis.IS_REACT_ACT_ENVIRONMENT
+      anyThis.IS_REACT_ACT_ENVIRONMENT = false
+      rerender()
+      anyThis.IS_REACT_ACT_ENVIRONMENT = prev
+    }
+    testEvents.addListener('rerender', cb)
+    return () => {
+      testEvents.removeListener('rerender', cb)
+    }
+  }, [])
+  return null
+}
+
+describe('toRerender', () => {
+  test('basic functionality', async () => {
+    const {takeRender, render} = createRenderStream({})
+
+    render(<RerenderingComponent />)
+    await expect(takeRender).toRerender()
+    await takeRender()
+
+    testEvents.emit('rerender')
+    await expect(takeRender).toRerender()
+    await takeRender()
+
+    await expect(takeRender).not.toRerender()
+  })
+})
+
+describe('toRenderExactlyTimes', () => {
+  test('basic functionality', async () => {
+    const {takeRender, render} = createRenderStream({})
+
+    render(<RerenderingComponent />)
+    testEvents.emit('rerender')
+
+    await expect(takeRender).toRenderExactlyTimes(2)
+  })
+})