chore: Make test run names able to handle refactoring

`fn.name` was introduced in Node 0.10.0, so this improves test suite maintainability without changing the minimum node version.

Also added a test that for certain proves that Promises can be awaited.

__test__/async-function.test.ts

@@ -2,13 +2,21 @@
 
 import {callAsyncFunction} from '../src/async-function'
 
-describe('callAsyncFunction', () => {
+describe(callAsyncFunction.name, () => {
   test('calls the function with its arguments', async () => {
     const result = await callAsyncFunction({foo: 'bar'} as any, 'return foo')
     expect(result).toEqual('bar')
   })
 
-  test('throws on ReferenceError', async () => {
+  test('can await a Promise', async () => {
+    const result = await callAsyncFunction(
+      {} as any,
+      'return await new Promise(resolve => resolve("bar"))'
+    )
+    expect(result).toEqual('bar')
+  })
+
+  test(`throws an ${ReferenceError.name}`, async () => {
     expect.assertions(1)
 
     try {

__test__/get-retry-options.test.ts

@@ -2,7 +2,7 @@
 
 import {getRetryOptions} from '../src/retry-options'
 
-describe('getRequestOptions', () => {
+describe(getRetryOptions.name, () => {
   test('retries disabled if retries == 0', async () => {
     const [retryOptions, requestOptions] = getRetryOptions(
       0,