inject
允许在 beforeEach() 和 it() 中注入依赖项。
Allows injecting dependencies in beforeEach() and it().
说明
例如:
Example:
      
      beforeEach(inject([Dependency, AClass], (dep, object) => {
  // some code that uses `dep` and `object`
  // ...
}));
it('...', inject([AClass], (object) => {
  object.doSomething();
  expect(...);
})
    注意:
Notes:
