Serrulien

// Better use this matcher than using toBeNull or toBeUndefined to test a DebugElement so as to avoid freezing the test.
// When expecting a DebugElement to be null but is not, jasmine will create a gigantic string describing the DebugElement.
// More on https://medium.com/@martatatiana/poor-detective-angular2-browser-crash-and-debugelement-f0a651dbf33
// e.g. expect(fixture.debugElement.query(By.css("img:first-of-type"))).toDebugElemExists();
// you can also use .not to negate the matcher.

beforeEach(() => {
    jasmine.addMatchers({
        toDebugElemExists: function (utils, customEqualityTesters) {
            return {