Add JSDoc and remove not needed check

packages/api-fetch/src/index.js

@@ -125,6 +125,12 @@ const defaultFetchHandler = ( nextOptions ) => {
 
 let fetchHandler = defaultFetchHandler;
 
+/**
+ * Defines a custom fetch handler for making the requests that will override
+ * the default one using window.fetch
+ *
+ * @param {Function} newFetchHandler The new fetch handler
+ */
 function setFetchHandler( newFetchHandler ) {
 	fetchHandler = newFetchHandler;
 }

packages/api-fetch/src/test/index.js

@@ -205,13 +205,12 @@ describe( 'apiFetch', () => {
 		// options object. It also assumes that some built-in middleware would
 		// either mutate or clone the original options if the extra middleware
 		// had been pushed to the stack.
-		expect.assertions( 2 );
+		expect.assertions( 1 );
 
 		const expectedOptions = {};
 
 		apiFetch.use( ( actualOptions, next ) => {
 			expect( actualOptions ).toBe( expectedOptions );
-			expect( actualOptions ).toEqual( expectedOptions );
 
 			return next( actualOptions );
 		} );