import { resetSharedImpl } from '../__mocks__/reset-shared-impl';
import { getOrCreateSharedImpl, getSharedImpl, STATE_KEY } from '../get-shared';

describe(`[datadog-rum] ${getOrCreateSharedImpl.name}`, () => {
    beforeEach(() => {
        resetSharedImpl();
    });

    const subject = () => getOrCreateSharedImpl();

    test('stores the instance under the well-known Symbol on globalThis', () => {
        const impl = subject();

        expect((globalThis as any)[STATE_KEY]).toBe(impl);
    });

    test('resolves the well-known Symbol from the package key', () => {
        expect(Symbol.for('@servicetitan/datadog-rum')).toBe(STATE_KEY);
    });

    describe('when an instance already exists', () => {
        let first: ReturnType<typeof getOrCreateSharedImpl>;

        beforeEach(() => {
            first = subject();
        });

        test('returns the same instance', () => {
            expect(subject()).toBe(first);
        });
    });
});

describe(`[datadog-rum] ${getSharedImpl.name}`, () => {
    beforeEach(() => {
        resetSharedImpl();
    });

    const subject = () => getSharedImpl();

    test('returns undefined', () => {
        expect(subject()).toBeUndefined();
    });

    describe('when an instance exists', () => {
        let impl: ReturnType<typeof getOrCreateSharedImpl>;

        beforeEach(() => {
            impl = getOrCreateSharedImpl();
        });

        test('returns existing instance', () => {
            expect(subject()).toBe(impl);
        });
    });
});