removed useless expect.assertions (#7131)

* removed useless expect.assertions

In a lot of case `expect.assertions(1);` is no need. It can be confusing.

* add changelog + some missing case I forgot

CHANGELOG.md

@@ -53,6 +53,7 @@
 - `[*]` Bump dated dependencies ([#6978](https://github.com/facebook/jest/pull/6978))
 - `[scripts]` Don’t make empty subfolders for ignored files in build folder ([#7001](https://github.com/facebook/jest/pull/7001))
 - `[docs]` Add missing export statement in `puppeteer_environment.js` under `docs/Puppeteer.md` ([#7127](https://github.com/facebook/jest/pull/7127))
+- `[docs]` Removed useless expect.assertions in `TestingAsyncCode.md` ([#7131](https://github.com/facebook/jest/pull/7131))
 - `[docs]` Remove references to `@providesModule` which isn't supported anymore ([#7147](https://github.com/facebook/jest/pull/7147))
 
 ## 23.6.0

docs/TestingAsyncCode.md

@@ -49,7 +49,6 @@ For example, let's say that `fetchData`, instead of using a callback, returns a
 
 ```js
 test('the data is peanut butter', () => {
-  expect.assertions(1);
   return fetchData().then(data => {
     expect(data).toBe('peanut butter');
   });
@@ -73,7 +72,6 @@ You can also use the `.resolves` matcher in your expect statement, and Jest will
 
 ```js
 test('the data is peanut butter', () => {
-  expect.assertions(1);
   return expect(fetchData()).resolves.toBe('peanut butter');
 });
 ```
@@ -84,7 +82,6 @@ If you expect a promise to be rejected use the `.rejects` matcher. It works anal
 
 ```js
 test('the fetch fails with an error', () => {
-  expect.assertions(1);
   return expect(fetchData()).rejects.toMatch('error');
 });
 ```
@@ -114,12 +111,10 @@ Of course, you can combine `async` and `await` with `.resolves` or `.rejects`.
 
 ```js
 test('the data is peanut butter', async () => {
-  expect.assertions(1);
   await expect(fetchData()).resolves.toBe('peanut butter');
 });
 
 test('the fetch fails with an error', async () => {
-  expect.assertions(1);
   await expect(fetchData()).rejects.toThrow('error');
 });
 ```