add renderToRenderStream test

Author: phryneas

src/__tests__/renderToRenderStream.test.tsx

@@ -0,0 +1,63 @@
+/* eslint-disable @typescript-eslint/no-use-before-define */
+import {describe, test, expect} from '@jest/globals'
+import {renderToRenderStream} from '@testing-library/react-render-stream'
+import {userEvent} from '@testing-library/user-event'
+import * as React from 'react'
+function CounterForm({
+  value,
+  onIncrement,
+}: {
+  value: number
+  onIncrement: () => void
+}) {
+  return (
+    <form>
+      <button type="button" onClick={() => onIncrement()}>
+        Increment
+      </button>
+      <label>
+        Value
+        <input type="number" value={value} readOnly />
+      </label>
+    </form>
+  )
+}
+
+describe('snapshotDOM', () => {
+  test('basic functionality', async () => {
+    function Counter() {
+      const [value, setValue] = React.useState(0)
+      return (
+        <CounterForm value={value} onIncrement={() => setValue(v => v + 1)} />
+      )
+    }
+
+    const {takeRender, renderResultPromise} = renderToRenderStream(
+      <Counter />,
+      {
+        snapshotDOM: true,
+      },
+    )
+    const utils = await renderResultPromise
+    const incrementButton = utils.getByText('Increment')
+    await userEvent.click(incrementButton)
+    await userEvent.click(incrementButton)
+    {
+      const {withinDOM} = await takeRender()
+      const input = withinDOM().getByLabelText<HTMLInputElement>('Value')
+      expect(input.value).toBe('0')
+    }
+    {
+      const {withinDOM} = await takeRender()
+      const input = withinDOM().getByLabelText<HTMLInputElement>('Value')
+      expect(input.value).toBe('1')
+    }
+    {
+      const {withinDOM} = await takeRender()
+      const input = withinDOM().getByLabelText<HTMLInputElement>('Value')
+      expect(input.value).toBe('2')
+    }
+  })
+})
+
+// for more tests, see the `createRenderStream` test suite, as `renderToRenderStream` is just a wrapper around that