87 lines
2.5 KiB
TypeScript
87 lines
2.5 KiB
TypeScript
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import {
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describe,
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expect,
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it,
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vi,
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} from 'vitest';
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import { createSingleton } from './createSingleton';
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describe('createSingleton', () => {
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it('does not call the factory until the first get (lazy)', () => {
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const factory = vi.fn(() => ({ id: 1 }));
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createSingleton(factory);
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expect(factory).not.toHaveBeenCalled();
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});
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it('constructs on first get and memoizes the instance', () => {
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const factory = vi.fn(() => ({ id: 1 }));
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const singleton = createSingleton(factory);
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const a = singleton.get();
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const b = singleton.get();
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expect(factory).toHaveBeenCalledTimes(1);
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expect(a).toBe(b);
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});
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it('rebuilds a fresh instance after reset', () => {
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let count = 0;
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const singleton = createSingleton(() => ({ id: ++count }));
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const first = singleton.get();
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singleton.reset();
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const second = singleton.get();
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expect(first).not.toBe(second);
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expect(second.id).toBe(2);
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});
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it('runs teardown once, with the live instance, on reset', () => {
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const teardown = vi.fn();
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const singleton = createSingleton(() => ({ id: 1 }), teardown);
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const instance = singleton.get();
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singleton.reset();
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expect(teardown).toHaveBeenCalledTimes(1);
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expect(teardown).toHaveBeenCalledWith(instance);
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});
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it('treats reset before any get as a no-op (no teardown, no throw)', () => {
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const teardown = vi.fn();
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const singleton = createSingleton(() => ({ id: 1 }), teardown);
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expect(() => singleton.reset()).not.toThrow();
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expect(teardown).not.toHaveBeenCalled();
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});
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it('does not run teardown again on a second consecutive reset', () => {
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const teardown = vi.fn();
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const singleton = createSingleton(() => ({ id: 1 }), teardown);
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singleton.get();
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singleton.reset();
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singleton.reset();
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expect(teardown).toHaveBeenCalledTimes(1);
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});
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it('works without a teardown', () => {
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const singleton = createSingleton(() => ({ id: 1 }));
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singleton.get();
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expect(() => singleton.reset()).not.toThrow();
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expect(singleton.get().id).toBe(1);
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});
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it('caches a falsy instance value without re-running the factory', () => {
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const factory = vi.fn(() => undefined);
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const singleton = createSingleton<undefined>(factory);
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singleton.get();
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singleton.get();
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expect(factory).toHaveBeenCalledTimes(1);
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});
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});
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