Fluent API overview

The FluentExpect API provides a way to string assertions together with the possibility of narrowing the scope, when it makes sense, allowing you to communicate expectations clearly and concisely.

Here is an example of assertions that narrow scopes:

Expect(viewModel)
  .to.have(v => v.someProp) // existence check + scope narrow
  .that.isInstanceOf(MyModel) // type check
  .and.that.has(p => p.itsOwnProp) // existence check + deepen scope
  .that.equals(3);

Forking scopes

Note that, at the fluent level, scopes can only narrow. To fork a scope, there are a few options. First, you can break it apart by assigning it to a variable:

let expectSomeProp = Expect(viewModel).to.have(v => v.someProp);
expectSomeProp.that.has(p => p.itsOwnProp);
expectSomeProp.that.has(p => p.someOther).that.equals(3);

Or, you can use properties matchers:

Expect(viewModel)
  .with.properties({
    someProp: p => Expect(p).to.beDefined(),
    someOther: 3,
  });