spec-js/operators/find-spec.js
"use strict";
var chai_1 = require('chai');
var Rx = require('../../dist/package/Rx');
var Observable = Rx.Observable;
/** @test {find} */
describe('Observable.prototype.find', function () {
function truePredicate(x) {
return true;
}
asDiagram('find(x => x % 5 === 0)')('should return matching element from source emits single element', function () {
var values = { a: 3, b: 9, c: 15, d: 20 };
var source = hot('---a--b--c--d---|', values);
var subs = '^ ! ';
var expected = '---------(c|) ';
var predicate = function (x) { return x % 5 === 0; };
expectObservable(source.find(predicate)).toBe(expected, values);
expectSubscriptions(source.subscriptions).toBe(subs);
});
it('should throw if not provided a function', function () {
chai_1.expect(function () {
Observable.of('yut', 'yee', 'sam').find('yee');
}).to.throw(TypeError, 'predicate is not a function');
});
it('should not emit if source does not emit', function () {
var source = hot('-');
var subs = '^';
var expected = '-';
expectObservable(source.find(truePredicate)).toBe(expected);
expectSubscriptions(source.subscriptions).toBe(subs);
});
it('should return undefined if source is empty to match predicate', function () {
var source = cold('|');
var subs = '(^!)';
var expected = '(x|)';
var result = source.find(truePredicate);
expectObservable(result).toBe(expected, { x: undefined });
expectSubscriptions(source.subscriptions).toBe(subs);
});
it('should return matching element from source emits single element', function () {
var source = hot('--a--|');
var subs = '^ !';
var expected = '--(a|)';
var predicate = function (value) {
return value === 'a';
};
expectObservable(source.find(predicate)).toBe(expected);
expectSubscriptions(source.subscriptions).toBe(subs);
});
it('should return matching element from source emits multiple elements', function () {
var source = hot('--a--b---c-|');
var subs = '^ !';
var expected = '-----(b|)';
var predicate = function (value) {
return value === 'b';
};
expectObservable(source.find(predicate)).toBe(expected);
expectSubscriptions(source.subscriptions).toBe(subs);
});
it('should work with a custom thisArg', function () {
var source = hot('--a--b---c-|');
var subs = '^ !';
var expected = '-----(b|)';
var finder = {
target: 'b'
};
var predicate = function (value) {
return value === this.target;
};
expectObservable(source.find(predicate, finder)).toBe(expected);
expectSubscriptions(source.subscriptions).toBe(subs);
});
it('should return undefined if element does not match with predicate', function () {
var source = hot('--a--b--c--|');
var subs = '^ !';
var expected = '-----------(x|)';
var predicate = function (value) {
return value === 'z';
};
expectObservable(source.find(predicate)).toBe(expected, { x: undefined });
expectSubscriptions(source.subscriptions).toBe(subs);
});
it('should allow unsubscribing early and explicitly', function () {
var source = hot('--a--b--c--|');
var subs = '^ ! ';
var expected = '------- ';
var unsub = ' ! ';
var result = source.find(function (value) { return value === 'z'; });
expectObservable(result, unsub).toBe(expected);
expectSubscriptions(source.subscriptions).toBe(subs);
});
it('should not break unsubscription chains when result is unsubscribed explicitly', function () {
var source = hot('--a--b--c--|');
var subs = '^ ! ';
var expected = '------- ';
var unsub = ' ! ';
var result = source
.mergeMap(function (x) { return Observable.of(x); })
.find(function (value) { return value === 'z'; })
.mergeMap(function (x) { return Observable.of(x); });
expectObservable(result, unsub).toBe(expected);
expectSubscriptions(source.subscriptions).toBe(subs);
});
it('should raise if source raise error while element does not match with predicate', function () {
var source = hot('--a--b--#');
var subs = '^ !';
var expected = '--------#';
var predicate = function (value) {
return value === 'z';
};
expectObservable(source.find(predicate)).toBe(expected);
expectSubscriptions(source.subscriptions).toBe(subs);
});
it('should raise error if predicate throws error', function () {
var source = hot('--a--b--c--|');
var subs = '^ !';
var expected = '--#';
var predicate = function (value) {
throw 'error';
};
expectObservable(source.find(predicate)).toBe(expected);
expectSubscriptions(source.subscriptions).toBe(subs);
});
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).find(function (foo) { return foo.baz === 42; })
.subscribe(function (x) { return x.baz; }); // x is still Foo
Observable.of(foo).find(isBar)
.subscribe(function (x) { return x.bar; }); // x is Bar!
var foobar = new Foo(); // type is interface, not the class
Observable.of(foobar).find(function (foobar) { return foobar.bar === 'name'; })
.subscribe(function (x) { return x.bar; }); // <-- x is still Bar
Observable.of(foobar).find(isBar)
.subscribe(function (x) { return x.bar; }); // <--- x is Bar!
var barish = { bar: 'quack', baz: 42 }; // type can quack like a Bar
Observable.of(barish).find(function (x) { return x.bar === 'quack'; })
.subscribe(function (x) { return x.bar; }); // x is still { bar: string; baz: number; }
Observable.of(barish).find(isBar)
.subscribe(function (bar) { return bar.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'; };
xs.find(isString)
.subscribe(function (s) { return s.length; }); // s is string
// In contrast, this type of regular boolean predicate still maintains the original type
xs.find(function (x) { return typeof x === 'number'; })
.subscribe(function (x) { return x; }); // x is still string | number
xs.find(function (x, i) { return typeof x === 'number' && x > i; })
.subscribe(function (x) { return x; }); // x is still string | number
}
// tslint:disable enable
});
});
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