spec/screenplay/questions/lists/List.spec.ts
import 'mocha';
import { given } from 'mocha-testdata';
import { actorCalled, Answerable, AnswersQuestions, Expectation, List, Question, UsesAbilities } from '../../../../src';
import { formatted } from '../../../../src/io';
import { expect } from '../../../expect';
import { isIdenticalTo } from '../../../isIdenticalTo';
describe('List', () => {
const Lisa = actorCalled('Lisa');
const q = <T>(value: T) =>
Question.about<T>('some string collection', actor => value);
const p = <T>(value: T) =>
Promise.resolve(value);
const isGreaterThan = (expected: number) =>
Expectation.thatActualShould('have value greater than', expected)
.soThat((actualValue: number, expectedValue: number) => actualValue > expectedValue);
describe('when wrapping an Array', () => {
const collection = [ 'first', 'second', 'third' ];
const examples = [ {
description: 'string[]',
answerable: collection,
collectionDescription: `[ 'first', 'second', 'third' ]`,
}, {
description: 'Question<string[]>',
answerable: q(collection),
collectionDescription: `some string collection`,
}, {
description: 'Promise<string[]>',
answerable: p(collection),
collectionDescription: `a Promise`,
}, {
description: 'Question<Promise<string[]>>',
answerable: q(p(collection)),
collectionDescription: `some string collection`,
}];
given(examples).
it('returns the number of items', ({ answerable }: { answerable: Answerable<string[]> }) =>
expect(List.of(answerable).count().answeredBy(Lisa))
.to.eventually.equal(3)
);
given(examples).
it('returns the underlying collection', ({ answerable }: { answerable: Answerable<string[]> }) =>
expect(List.of(answerable).answeredBy(Lisa))
.to.eventually.deep.equal(collection)
);
given(examples).
it('returns the first item from the collection', ({ answerable }: { answerable: Answerable<string[]> }) =>
expect(List.of(answerable).first().answeredBy(Lisa))
.to.eventually.deep.equal(collection[0])
);
given(examples).
it('returns the last item from the collection', ({ answerable }: { answerable: Answerable<string[]> }) =>
expect(List.of(answerable).last().answeredBy(Lisa))
.to.eventually.deep.equal(collection[collection.length - 1])
);
given(examples).
it('returns the nth item from the collection', ({ answerable }: { answerable: Answerable<string[]> }) =>
expect(List.of(answerable).get(1).answeredBy(Lisa))
.to.eventually.deep.equal(collection[1])
);
describe('provides a sensible description when it', () => {
given(examples).
it('returns the number of items', ({ answerable, collectionDescription }: { answerable: Answerable<string[]>, collectionDescription: string }) =>
expect(List.of(answerable).count().toString())
.to.equal(`the number of ${ collectionDescription }`)
);
given(examples).
it('returns the underlying collection', ({ answerable, collectionDescription }: { answerable: Answerable<string[]>, collectionDescription: string }) =>
expect(List.of(answerable).toString())
.to.equal(collectionDescription)
);
given(examples).
it('returns the first item from the collection', ({ answerable, collectionDescription }: { answerable: Answerable<string[]>, collectionDescription: string }) =>
expect(List.of(answerable).first().toString())
.to.equal(`the first of ${ collectionDescription }`)
);
given(examples).
it('returns the last item from the collection', ({ answerable, collectionDescription }: { answerable: Answerable<string[]>, collectionDescription: string }) =>
expect(List.of(answerable).last().toString())
.to.equal(`the last of ${ collectionDescription }`)
);
given(examples).
it('returns the nth item from the collection', ({ answerable, collectionDescription }: { answerable: Answerable<string[]>, collectionDescription: string }) =>
expect(List.of(answerable).get(1).toString())
.to.equal(`the 2nd of ${ collectionDescription }`)
);
given([
{ description: '1st', index: 0 },
{ description: '2nd', index: 1 },
{ description: '3rd', index: 2 },
{ description: '4th', index: 3 },
{ description: '5th', index: 4 },
{ description: '10th', index: 9 },
{ description: '11th', index: 10 },
{ description: '20th', index: 19 },
{ description: '42nd', index: 41 },
{ description: '115th', index: 114 },
{ description: '1522nd', index: 1521 },
]).
it('returns the nth item', ({ description, index }) => {
expect(List.of(examples[1].answerable).get(index).toString())
.to.equal(`the ${ description } of some string collection`);
});
});
describe('and using filters', () => {
interface Person {
name: string;
age: number;
pets: number;
}
const
alice = { name: 'Alice', age: 27, pets: 3 },
bob = { name: 'Bob', age: 42, pets: 1 },
cindy = { name: 'Cindy', age: 55, pets: 3 };
const people = [ alice, bob, cindy ];
class Name extends Question<Promise<string>> {
static of(person: Answerable<Person>): Question<Promise<string>> {
return new Name(person);
}
constructor(private readonly person: Answerable<Person>) {
super(formatted `the name of ${ person }`);
}
answeredBy(actor: AnswersQuestions & UsesAbilities): Promise<string> {
return actor.answer(this.person)
.then(person => person.name);
}
}
const PropertyCalled = <K extends keyof Person>(name: K) => ({
of: (person: Answerable<Person>) =>
Question.about(formatted `${ name } of ${ person }`, actor => {
return actor.answer(person).then(answer => answer[name]);
}),
toString() {
return `property "${ name }"`;
}
});
/** @test {List#of} */
it('lets you narrow down the list of items to those that match the filter', async () => {
const found = await List.of(people)
.where(Name, isIdenticalTo('Bob'))
.first()
.answeredBy(Lisa);
expect(found).to.deep.equal(bob);
});
/** @test {List#of} */
it('lets you narrow down the list of items to those that match the filter', async () => {
const found = await List.of(people)
.where(Name, isIdenticalTo('Bob'))
.first()
.answeredBy(Lisa);
expect(found).to.deep.equal(bob);
});
/** @test {List#of} */
it('lets you narrow down the list of items to those that match several filters', async () => {
const found = await List.of(people)
.where(PropertyCalled('pets'), isIdenticalTo(3))
.where(PropertyCalled('age'), isGreaterThan(30))
.first()
.answeredBy(Lisa);
expect(found).to.deep.equal(cindy);
});
/** @test {List#of} */
it('describes the filters applied', () => {
const People = () =>
Question.about('people', actor => people);
const items = List.of(People())
.where(PropertyCalled('pets'), isIdenticalTo(3))
.where(PropertyCalled('age'), isGreaterThan(30))
.first();
expect(items.toString())
.to.equal('the first of people where property "pets" does have value identical to 3 and property "age" does have value greater than 30')
});
});
});
});