@aegis-techno/ngx-testing-tools
v17.0.0
Published
Given When Then concepts for jest.
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NgxTestingTools
This library is a helper that encourages leaner, meaner specs.
It provide Given When Then Concepts and mock tool for Jest and Angular
Running unit tests
Run ng test ngx-testing-tools
to execute the unit tests via jest.
Given When Then Concepts
This library is a helper that encourages leaner, meaner specs using Given, When, and Then.
The basic idea behind this is a humble acknowledgement of given-when-then as the best English language analogue we have to arrange-act-assert
Prior Art + Credit
The concept (and implementation) is based on the work of HiRez.io, who've done an amazing implementation of the original jasmine-given library by Justin Searls, which is in turn based on rspec-given by Jim Weirich.
Example
describe('A context', () => {
let fakeNumber: number;
let actualResult: any;
function addTwo(num: number) {
return num + 2;
}
Given(() => {
fakeNumber = undefined;
actualResult = undefined;
});
describe('should run "Given" before "When" and "When" before "Then"', () => {
Given(() => {
fakeNumber = 2;
});
When(() => {
actualResult = addTwo(fakeNumber);
});
Then(() => {
expect(actualResult).toBe(4);
});
});
describe("redundant test execution example", () => {
context("a traditional spec with numerous Then statements", () => {
var timesGivenWasInvoked = 0,
timesWhenWasInvoked = 0;
Given(() => {
timesGivenWasInvoked++;
});
When(() => {
timesWhenWasInvoked++;
});
Then(() => expect(timesGivenWasInvoked).toBe(1));
Then(() => expect(timesWhenWasInvoked).toBe(2));
Then(() => expect(timesGivenWasInvoked).toBe(3));
Then(() => expect(timesWhenWasInvoked).toBe(4));
});
context("a spec with one Then and multiple And statements", () => {
var timesGivenWasInvoked = 0,
timesWhenWasInvoked = 0;
Given(() => {
timesGivenWasInvoked++;
});
When(() => {
timesWhenWasInvoked++;
});
Then(() => expect(timesGivenWasInvoked).toBe(1));
And(() => expect(timesWhenWasInvoked).toBe(1));
And(() => expect(timesGivenWasInvoked).toBe(1));
And(() => expect(timesWhenWasInvoked).toBe(1));
Then(() => expect(timesWhenWasInvoked).toBe(2));
});
});
Given
The Given section specifies a starting point, a set of preconditions that must be true before the code under test is allowed to be run. In standard test frameworks the preconditions are established with a combination of setup methods
When
The When clause specifies the code to be tested ... oops, excuse me ... specified. After the preconditions in the given section are met, the when code block is run.
Then / ThenExpect
The Then clauses are the postconditions of the specification. These then conditions must be true after the code under test (the When clause) is run.
And
The And clauses are play after the Then clause find before. The And clauses don't support "random order running test".
Mock
Utils method :
configureTestBed(moduleDef?: TestModuleMetadata)
, for the configuration of the TestBed in a Given.createTestContext(component: Type<T>)
, for create un wrapper of a fixture for the component class given.provideSpyObjForClass
, create a SpyObj.injectMock(classType: Type<T> | AbstractType<T>)
, for retreive a mock.
Usage
describe('MyComponent', () => {
let testContext: TestContext<MyComponent>;
configureTestBed({
providers: [
provideSpyObjForClass(MyService)
]
},
);
Given(() => {
injectMock(MyService).foo.and.returnValue(["TEST"]);
})
When(async () => {
testContext = createTestContext(MyComponent);
await testContext.whenStable();
});
Then('should be created', () => {
expect(testContext.component).toBeTruthy();
});
Then('should have retrieve data from service', () => {
expect(testContext.component.bar).toBe("TEST");
});
});