@reactivex/rxjs
Version:
Reactive Extensions for modern JavaScript
243 lines • 11.6 kB
JavaScript
;
var chai_1 = require('chai');
var Rx = require('../../dist/cjs/Rx');
var Observable = Rx.Observable;
/** @test {first} */
describe('Observable.prototype.first', function () {
asDiagram('first')('should take the first value of an observable with many values', function () {
var e1 = hot('-----a--b--c---d---|');
var expected = '-----(a|) ';
var sub = '^ ! ';
expectObservable(e1.first()).toBe(expected);
expectSubscriptions(e1.subscriptions).toBe(sub);
});
it('should take the first value of an observable with one value', function () {
var e1 = hot('---(a|)');
var expected = '---(a|)';
var sub = '^ !';
expectObservable(e1.first()).toBe(expected);
expectSubscriptions(e1.subscriptions).toBe(sub);
});
it('should error on empty', function () {
var e1 = hot('--a--^----|');
var expected = '-----#';
var sub = '^ !';
expectObservable(e1.first()).toBe(expected, null, new Rx.EmptyError());
expectSubscriptions(e1.subscriptions).toBe(sub);
});
it('should return the default value if source observable was empty', function () {
var e1 = hot('-----^----|');
var expected = '-----(a|)';
var sub = '^ !';
expectObservable(e1.first(null, null, 'a')).toBe(expected);
expectSubscriptions(e1.subscriptions).toBe(sub);
});
it('should only emit one value in recursive cases', function () {
var subject = new Rx.Subject();
var results = [];
subject.first().subscribe(function (x) {
results.push(x);
subject.next(x + 1);
});
subject.next(0);
chai_1.expect(results).to.deep.equal([0]);
});
it('should propagate error from the source observable', function () {
var e1 = hot('---^---#');
var expected = '----#';
var sub = '^ !';
expectObservable(e1.first()).toBe(expected);
expectSubscriptions(e1.subscriptions).toBe(sub);
});
it('should go on forever on never', function () {
var e1 = hot('--^-------');
var expected = '--------';
var sub = '^ ';
expectObservable(e1.first()).toBe(expected);
expectSubscriptions(e1.subscriptions).toBe(sub);
});
it('should allow unsubscribing early and explicitly', function () {
var e1 = hot('--a--^-----b----c---d--|');
var e1subs = '^ ! ';
var expected = '---- ';
var unsub = ' ! ';
expectObservable(e1.first(), unsub).toBe(expected);
expectSubscriptions(e1.subscriptions).toBe(e1subs);
});
it('should not break unsubscription chains when result is unsubscribed explicitly', function () {
var e1 = hot('--a--^-----b----c---d--|');
var e1subs = '^ ! ';
var expected = '---- ';
var unsub = ' ! ';
var result = e1
.mergeMap(function (x) { return Observable.of(x); })
.first()
.mergeMap(function (x) { return Observable.of(x); });
expectObservable(result, unsub).toBe(expected);
expectSubscriptions(e1.subscriptions).toBe(e1subs);
});
it('should return first value that matches a predicate', function () {
var e1 = hot('--a-^--b--c--a--c--|');
var expected = '------(c|)';
var sub = '^ !';
var predicate = function (value) {
return value === 'c';
};
expectObservable(e1.first(predicate)).toBe(expected);
expectSubscriptions(e1.subscriptions).toBe(sub);
});
it('should return first value that matches a predicate for odd numbers', function () {
var e1 = hot('--a-^--b--c--d--e--|', { a: 1, b: 2, c: 3, d: 4, e: 5 });
var expected = '------(c|)';
var sub = '^ !';
var predicate = function (value) {
return value % 2 === 1;
};
expectObservable(e1.first(predicate)).toBe(expected, { c: 3 });
expectSubscriptions(e1.subscriptions).toBe(sub);
});
it('should error when no value matches the predicate', function () {
var e1 = hot('--a-^--b--c--a--c--|');
var expected = '---------------#';
var sub = '^ !';
var predicate = function (value) {
return value === 's';
};
expectObservable(e1.first(predicate)).toBe(expected, null, new Rx.EmptyError());
expectSubscriptions(e1.subscriptions).toBe(sub);
});
it('should return the default value when no value matches the predicate', function () {
var e1 = hot('--a-^--b--c--a--c--|');
var expected = '---------------(d|)';
var sub = '^ !';
var predicate = function (value) {
return value === 's';
};
expectObservable(e1.first(predicate, null, 'd')).toBe(expected);
expectSubscriptions(e1.subscriptions).toBe(sub);
});
it('should propagate error when no value matches the predicate', function () {
var e1 = hot('--a-^--b--c--a--#');
var expected = '------------#';
var sub = '^ !';
var predicate = function (value) {
return value === 's';
};
expectObservable(e1.first(predicate)).toBe(expected);
expectSubscriptions(e1.subscriptions).toBe(sub);
});
it('should return first value that matches the index in the predicate', function () {
var e1 = hot('--a-^--b--c--a--c--|');
var expected = '---------(a|)';
var sub = '^ !';
var predicate = function (value, index) {
return index === 2;
};
expectObservable(e1.first(predicate)).toBe(expected);
expectSubscriptions(e1.subscriptions).toBe(sub);
});
it('should propagate error from predicate', function () {
var e1 = hot('--a-^--b--c--d--e--|', { a: 1, b: 2, c: 3, d: 4, e: 5 });
var expected = '---------#';
var sub = '^ !';
var predicate = function (value) {
if (value < 4) {
return false;
}
else {
throw 'error';
}
};
expectObservable(e1.first(predicate)).toBe(expected, null, 'error');
expectSubscriptions(e1.subscriptions).toBe(sub);
});
it('should support a result selector argument', function () {
var e1 = hot('--a--^---b---c---d---e--|');
var expected = '--------(x|)';
var sub = '^ !';
var predicate = function (x) { return x === 'c'; };
var resultSelector = function (x, i) {
chai_1.expect(i).to.equal(1);
chai_1.expect(x).to.equal('c');
return 'x';
};
expectObservable(e1.first(predicate, resultSelector)).toBe(expected);
expectSubscriptions(e1.subscriptions).toBe(sub);
});
it('should raise error when result selector throws', function () {
var e1 = hot('--a--^---b---c---d---e--|');
var expected = '--------#';
var sub = '^ !';
var predicate = function (x) { return x === 'c'; };
var resultSelector = function (x, i) {
throw 'error';
};
expectObservable(e1.first(predicate, resultSelector)).toBe(expected);
expectSubscriptions(e1.subscriptions).toBe(sub);
});
it('should support type guards without breaking previous behavior', function () {
// tslint:disable no-unused-variable
// type guards with interfaces and classes
{
var Foo = (function () {
function Foo(bar, baz) {
if (bar === void 0) { bar = 'name'; }
if (baz === void 0) { baz = 42; }
this.bar = bar;
this.baz = baz;
}
return Foo;
}());
var isBar = function (x) { return x && x.bar !== undefined; };
var isBaz = function (x) { return x && x.baz !== undefined; };
var foo = new Foo();
Observable.of(foo).first()
.subscribe(function (x) { return x.baz; }); // x is Foo
Observable.of(foo).first(function (foo) { return foo.bar === 'name'; })
.subscribe(function (x) { return x.baz; }); // x is still Foo
Observable.of(foo).first(isBar)
.subscribe(function (x) { return x.bar; }); // x is Bar!
var foobar = new Foo(); // type is the interface, not the class
Observable.of(foobar).first()
.subscribe(function (x) { return x.bar; }); // x is Bar
Observable.of(foobar).first(function (foobar) { return foobar.bar === 'name'; })
.subscribe(function (x) { return x.bar; }); // x is still Bar
Observable.of(foobar).first(isBaz)
.subscribe(function (x) { return x.baz; }); // x is Baz!
var barish = { bar: 'quack', baz: 42 }; // type can quack like a Bar
Observable.of(barish).first()
.subscribe(function (x) { return x.baz; }); // x is still { bar: string; baz: number; }
Observable.of(barish).first(function (x) { return x.bar === 'quack'; })
.subscribe(function (x) { return x.bar; }); // x is still { bar: string; baz: number; }
Observable.of(barish).first(isBar)
.subscribe(function (x) { return x.bar; }); // x is Bar!
}
// type guards with primitive types
{
var xs = Observable.from([1, 'aaa', 3, 'bb']);
// This type guard will narrow a `string | number` to a string in the examples below
var isString = function (x) { return typeof x === 'string'; };
// missing predicate preserves the type
xs.first().subscribe(function (x) { return x; }); // x is still string | number
// After the type guard `first` predicates, the type is narrowed to string
xs.first(isString)
.subscribe(function (s) { return s.length; }); // s is string
xs.first(isString, function (s) { return s.substr(0); }) // s is string in predicate
.subscribe(function (s) { return s.length; }); // s is string
// boolean predicates preserve the type
xs.first(function (x) { return typeof x === 'string'; })
.subscribe(function (x) { return x; }); // x is still string | number
xs.first(function (x) { return !!x; }, function (x) { return x; })
.subscribe(function (x) { return x; }); // x is still string | number
xs.first(function (x) { return typeof x === 'string'; }, function (x) { return x; }, '') // default is string; x remains string | number
.subscribe(function (x) { return x; }); // x is still string | number
// `first` still uses the `resultSelector` return type, if it exists.
xs.first(function (x) { return typeof x === 'string'; }, function (x) { return ({ str: "" + x }); }) // x remains string | number
.subscribe(function (o) { return o.str; }); // o is { str: string }
xs.first(function (x) { return typeof x === 'string'; }, function (x) { return ({ str: "" + x }); }, { str: '' })
.subscribe(function (o) { return o.str; }); // o is { str: string }
}
// tslint:disable enable
});
});
//# sourceMappingURL=first-spec.js.map