chore: remove deprecated assertion

src/__tests__/auto-cleanup.js

@@ -9,5 +9,5 @@ test('first', () => {
 })
 
 test('second', () => {
-  expect(document.body).toBeEmpty()
+  expect(document.body).toBeEmptyDOMElement()
 })

src/__tests__/cleanup.js

@@ -18,7 +18,7 @@ test('cleans up the document', async () => {
 
   render(<Test />)
   await cleanup()
-  expect(document.body).toBeEmpty()
+  expect(document.body).toBeEmptyDOMElement()
   expect(spy).toHaveBeenCalledTimes(1)
 })
 

src/__tests__/stopwatch.js

@@ -47,7 +47,7 @@ test('unmounts a component', async () => {
   // hey there reader! You don't need to have an assertion like this one
   // this is just me making sure that the unmount function works.
   // You don't need to do this in your apps. Just rely on the fact that this works.
-  expect(container).toBeEmpty()
+  expect(container).toBeEmptyDOMElement()
   // just wait to see if the interval is cleared or not
   // if it's not, then we'll call setState on an unmounted component
   // and get an error.