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feat: subscriptions (server-streams) + observable (#22)
* subscriptions v0.8.0 * fix lint errors * add datatypes export to package json * make observable a fixture instead of a top-level thing * fix package.json, return on stream done rather than explicitly checking value
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,50 @@ | ||
| import { Observable } from './observable'; | ||
| import { describe, expect, test, vitest } from 'vitest'; | ||
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| describe('Observable', () => { | ||
| test('should set initial value correctly', () => { | ||
| const initialValue = 10; | ||
| const observable = new Observable(initialValue); | ||
| expect(observable.value).toBe(initialValue); | ||
| }); | ||
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| test('should update value correctly', () => { | ||
| const observable = new Observable(10); | ||
| const newValue = 20; | ||
| observable.set(() => newValue); | ||
| expect(observable.value).toBe(newValue); | ||
| }); | ||
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| test('should notify listeners when value changes', () => { | ||
| const observable = new Observable(10); | ||
| const listener = vitest.fn(); | ||
| observable.observe(listener); | ||
| expect(listener).toHaveBeenCalledTimes(1); | ||
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| const newValue = 20; | ||
| observable.set(() => newValue); | ||
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| expect(listener).toHaveBeenCalledTimes(2); | ||
| expect(listener).toHaveBeenCalledWith(newValue); | ||
| }); | ||
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| test('should unsubscribe from notifications', () => { | ||
| const observable = new Observable(10); | ||
| const listener = vitest.fn(); | ||
| const unsubscribe = observable.observe(listener); | ||
| expect(listener).toHaveBeenCalledTimes(1); | ||
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| const newValue = 20; | ||
| observable.set(() => newValue); | ||
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| expect(listener).toHaveBeenCalledTimes(2); | ||
| expect(listener).toHaveBeenCalledWith(newValue); | ||
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| unsubscribe(); | ||
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| const anotherValue = 30; | ||
| observable.set(() => anotherValue); | ||
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| expect(listener).toHaveBeenCalledTimes(2); // should not be called again after unsubscribing | ||
| }); | ||
| }); |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,42 @@ | ||
| /** | ||
| * Represents an observable value that can be subscribed to for changes. | ||
| * This should only be used in tests | ||
| * @template T - The type of the value being observed. | ||
| */ | ||
| export class Observable<T> { | ||
| value: T; | ||
| private listeners: Set<(val: T) => void>; | ||
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| constructor(initialValue: T) { | ||
| this.value = initialValue; | ||
| this.listeners = new Set(); | ||
| } | ||
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| /** | ||
| * Gets the current value of the observable. | ||
| */ | ||
| get() { | ||
| return this.value; | ||
| } | ||
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| /** | ||
| * Sets the current value of the observable. All listeners will get an update with this value. | ||
| * @param newValue - The new value to set. | ||
| */ | ||
| set(tx: (preValue: T) => T) { | ||
| const newValue = tx(this.value); | ||
| this.value = newValue; | ||
| this.listeners.forEach((listener) => listener(newValue)); | ||
| } | ||
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| /** | ||
| * Subscribes to changes in the observable value. | ||
| * @param listener - A callback function that will be called when the value changes. | ||
| * @returns A function that can be called to unsubscribe from further notifications. | ||
| */ | ||
| observe(listener: (val: T) => void) { | ||
| this.listeners.add(listener); | ||
| listener(this.get()); | ||
| return () => this.listeners.delete(listener); | ||
| } | ||
| } |
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