anchor.diff:    1. [Test a component with an external template](#component-with-external-template)
       - [_async_](#async-in-before-each) in `beforeEach`
       - [_compileComponents_](#compile-components)
  -  1. [Test a component with inputs and outputs](#component-with-inputs-output)
  +  1. [Test a component with inputs and outputs](#component-with-inputs-outputs)
       - [_triggerEventHandler_](#trigger-event-handler)
     1. [Test a component inside a test host component](#component-inside-test-host)
     <br><br>
  
positive.code:   1. [Angular testing utility APIs](#atu-apis)
      - [Stand-alone functions](#atu-apis): `async`, `fakeAsync`, etc.
      - [_TestBed_](#testbed-class-summary)
      - [_ComponentFixture_](#component-fixture-class-summary)
      - [_DebugElement_](#debug-element-details)
    1. [FAQ](#faq "Frequently asked questions")
  :marked
  
negative.code:   the configuration adds a `UserService` provider to the `providers` list.
    But not the real `UserService`.
    
  #service-test-doubles 
  :marked
    ## Provide service test doubles
  
  