Mastering TypeScript 3 - Third Edition

Matchers

As seen in our first simple test, Jasmine uses a fluent syntax to allow us to attach Jasmine matchers after the expect(...) statement. In our first test, we used the .toBeDefined matcher. Jasmine, however, has a wide range of matchers that can be used within tests, and also allows us to write and include custom matchers. Let's take a quick look at some of these matchers:

it("expect value toBe(2)", () => { 
    let twoValue = 2; 
    expect(twoValue).toBe(2); 
})

Here, we are using the .toBe matcher to test that the value of the twoValue variable is indeed 2.

it("expect string toContain value ", () => { 
    let testString = "12345a"; 
    expect(testString).toContain("a"); 
}); 

In this test, we are using the toContain matcher to test that the "12345a" ...