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126 lines
3.3 KiB
126 lines
3.3 KiB
import { assert } from 'chai';
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import { Signal } from 'app/client/lib/Signal';
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describe('Signal', function() {
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it('computes new signal from other events', function() {
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const started = Signal.create(null, false);
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const hovered = Signal.create(null, false);
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const hoverAndStarted = Signal.compute(null, on => on(started) && on(hovered));
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let flag: any = 'not-called';
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hoverAndStarted.listen(val => flag = val);
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function start(emit: boolean, expected: boolean) {
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started.emit(emit);
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assert.equal(flag, expected);
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flag = 'not-called';
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}
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function hover(emit: boolean, expected: boolean) {
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hovered.emit(emit);
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assert.equal(flag, expected);
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flag = 'not-called';
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}
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start(true, false);
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start(false, false);
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start(true, false);
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hover(true, true);
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hover(false, false);
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hover(true, true);
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start(false, false);
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});
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it('works as flag', function() {
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const started = Signal.create(null, false);
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const hovered = Signal.create(null, false);
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const andEvent = Signal.compute(null, on => on(started) && on(hovered)).distinct();
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const notCalled = {};
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let andCalled = notCalled;
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andEvent.listen(val => andCalled = val);
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function start(emit: boolean, expected: any) {
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started.emit(emit);
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assert.equal(andCalled, expected);
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andCalled = notCalled;
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}
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start(true, notCalled);
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start(false, notCalled);
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start(true, notCalled);
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function hover(emit: boolean, expected: any) {
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hovered.emit(emit);
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assert.equal(andCalled, expected);
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andCalled = notCalled;
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}
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hover(true, true);
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hover(false, false);
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hover(true, true);
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start(false, false);
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});
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it('supports basic compositions', function() {
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const numbers = Signal.create(null, 0);
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const even = numbers.filter(n => n % 2 === 0);
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const odd = numbers.filter(n => n % 2 === 1);
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let evenCount = 0;
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let oddCount = 0;
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even.listen(() => evenCount++);
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odd.listen(() => oddCount++);
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assert.equal(evenCount, 0);
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assert.equal(oddCount, 0);
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numbers.emit(2);
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assert.equal(evenCount, 1);
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assert.equal(oddCount, 0);
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numbers.emit(3);
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assert.equal(evenCount, 1);
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assert.equal(oddCount, 1);
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const distinct = numbers.distinct();
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let distinctCount = 0;
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distinct.listen(() => distinctCount++);
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assert.equal(distinctCount, 0);
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numbers.emit(3);
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assert.equal(distinctCount, 0);
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numbers.emit(3);
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assert.equal(distinctCount, 0);
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numbers.emit(4);
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assert.equal(distinctCount, 1);
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numbers.emit(4);
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assert.equal(distinctCount, 1);
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numbers.emit(5);
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assert.equal(distinctCount, 2);
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const trafficLight = Signal.create(null, false);
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const onRoad = numbers.filter(n => !!trafficLight.state.get());
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let onRoadCount = 0;
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onRoad.listen(() => onRoadCount++);
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assert.equal(onRoadCount, 0);
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numbers.emit(5);
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assert.equal(onRoadCount, 0);
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trafficLight.emit(true);
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assert.equal(onRoadCount, 0);
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numbers.emit(6);
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assert.equal(onRoadCount, 1);
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});
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it('detects cycles', function() {
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const first = Signal.create(null, 0);
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const second = Signal.create(null, 0);
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first.listen(n => second.emit(n + 1));
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second.listen(n => first.emit(n + 1));
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assert.throws(() => first.emit(1));
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});
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});
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