@reactivex/rxjs
Version:
Reactive Extensions for modern JavaScript
183 lines • 9.09 kB
JavaScript
;
var chai_1 = require('chai');
var Rx = require('../../dist/cjs/Rx');
var Observable = Rx.Observable;
/** @test {last} */
describe('Observable.prototype.last', function () {
asDiagram('last')('should take the last value of an observable', function () {
var e1 = hot('--a----b--c--|');
var e1subs = '^ !';
var expected = '-------------(c|)';
expectObservable(e1.last()).toBe(expected);
expectSubscriptions(e1.subscriptions).toBe(e1subs);
});
it('should error on nothing sent but completed', function () {
var e1 = hot('--a--^----|');
var e1subs = '^ !';
var expected = '-----#';
expectObservable(e1.last()).toBe(expected, null, new Rx.EmptyError());
expectSubscriptions(e1.subscriptions).toBe(e1subs);
});
it('should error on empty', function () {
var e1 = cold('|');
var e1subs = '(^!)';
var expected = '#';
expectObservable(e1.last()).toBe(expected, null, new Rx.EmptyError());
expectSubscriptions(e1.subscriptions).toBe(e1subs);
});
it('should go on forever on never', function () {
var e1 = cold('-');
var e1subs = '^';
var expected = '-';
expectObservable(e1.last()).toBe(expected);
expectSubscriptions(e1.subscriptions).toBe(e1subs);
});
it('should return last element matches with predicate', function () {
var e1 = hot('--a--b--a--b--|');
var e1subs = '^ !';
var expected = '--------------(b|)';
var predicate = function (value) {
return value === 'b';
};
expectObservable(e1.last(predicate)).toBe(expected);
expectSubscriptions(e1.subscriptions).toBe(e1subs);
});
it('should allow unsubscribing explicitly and early', function () {
var e1 = hot('--a--b--c--d--|');
var unsub = ' ! ';
var e1subs = '^ ! ';
var expected = '-------- ';
expectObservable(e1.last(), 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 Rx.Observable.of(x); })
.last()
.mergeMap(function (x) { return Rx.Observable.of(x); });
expectObservable(result, unsub).toBe(expected);
expectSubscriptions(e1.subscriptions).toBe(e1subs);
});
it('should return a default value if no element found', function () {
var e1 = cold('|');
var e1subs = '(^!)';
var expected = '(a|)';
expectObservable(e1.last(null, null, 'a')).toBe(expected);
expectSubscriptions(e1.subscriptions).toBe(e1subs);
});
it('should not return default value if an element is found', function () {
var e1 = hot('--a---^---b---c---d---|');
var e1subs = '^ !';
var expected = '----------------(d|)';
expectObservable(e1.last(null, null, 'x')).toBe(expected);
expectSubscriptions(e1.subscriptions).toBe(e1subs);
});
it('should support a result selector argument', function () {
var e1 = hot('--a--^---b---c---d---e--|');
var e1subs = '^ !';
var expected = '-------------------(x|)';
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.last(predicate, resultSelector)).toBe(expected);
expectSubscriptions(e1.subscriptions).toBe(e1subs);
});
it('should raise error when predicate throws', function () {
var e1 = hot('--a--^---b---c---d---e--|');
var e1subs = '^ ! ';
var expected = '--------# ';
var predicate = function (x) {
if (x === 'c') {
throw 'error';
}
else {
return false;
}
};
expectObservable(e1.last(predicate)).toBe(expected);
expectSubscriptions(e1.subscriptions).toBe(e1subs);
});
it('should raise error when result selector throws', function () {
var e1 = hot('--a--^---b---c---d---e--|');
var e1subs = '^ ! ';
var expected = '--------# ';
var predicate = function (x) { return x === 'c'; };
var resultSelector = function (x, i) {
throw 'error';
};
expectObservable(e1.last(predicate, resultSelector)).toBe(expected);
expectSubscriptions(e1.subscriptions).toBe(e1subs);
});
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).last()
.subscribe(function (x) { return x.baz; }); // x is Foo
Observable.of(foo).last(function (foo) { return foo.bar === 'name'; })
.subscribe(function (x) { return x.baz; }); // x is still Foo
Observable.of(foo).last(isBar)
.subscribe(function (x) { return x.bar; }); // x is Bar!
var foobar = new Foo(); // type is the interface, not the class
Observable.of(foobar).last()
.subscribe(function (x) { return x.bar; }); // x is Bar
Observable.of(foobar).last(function (foobar) { return foobar.bar === 'name'; })
.subscribe(function (x) { return x.bar; }); // x is still Bar
Observable.of(foobar).last(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).last()
.subscribe(function (x) { return x.baz; }); // x is still { bar: string; baz: number; }
Observable.of(barish).last(function (x) { return x.bar === 'quack'; })
.subscribe(function (x) { return x.bar; }); // x is still { bar: string; baz: number; }
Observable.of(barish).last(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.last().subscribe(function (x) { return x; }); // x is still string | number
// After the type guard `last` predicates, the type is narrowed to string
xs.last(isString)
.subscribe(function (s) { return s.length; }); // s is string
xs.last(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.last(function (x) { return typeof x === 'string'; })
.subscribe(function (x) { return x; }); // x is still string | number
xs.last(function (x) { return !!x; }, function (x) { return x; })
.subscribe(function (x) { return x; }); // x is still string | number
xs.last(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
// `last` still uses the `resultSelector` return type, if it exists.
xs.last(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.last(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=last-spec.js.map