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371 lines
6.8 KiB
371 lines
6.8 KiB
import * as assert from 'assert';
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import { readable, writable, derived, get } from '../../store';
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describe('store', () => {
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describe('writable', () => {
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it('creates a writable store', () => {
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const count = writable(0);
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const values = [];
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const unsubscribe = count.subscribe(value => {
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values.push(value);
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});
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count.set(1);
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count.update(n => n + 1);
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unsubscribe();
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count.set(3);
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count.update(n => n + 1);
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assert.deepEqual(values, [0, 1, 2]);
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});
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it('calls provided subscribe handler', () => {
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let called = 0;
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const store = writable(0, () => {
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called += 1;
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return () => called -= 1;
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});
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const unsubscribe1 = store.subscribe(() => { });
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assert.equal(called, 1);
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const unsubscribe2 = store.subscribe(() => { });
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assert.equal(called, 1);
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unsubscribe1();
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assert.equal(called, 1);
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unsubscribe2();
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assert.equal(called, 0);
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});
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it('does not assume immutable data', () => {
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const obj = {};
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let called = 0;
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const store = writable(obj);
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store.subscribe(() => {
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called += 1;
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});
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store.set(obj);
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assert.equal(called, 2);
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store.update(obj => obj);
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assert.equal(called, 3);
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});
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it('only calls subscriber once initially, including on resubscriptions', () => {
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let num = 0;
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const store = writable(num, set => set(num += 1));
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let count1 = 0;
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let count2 = 0;
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store.subscribe(() => count1 += 1)();
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assert.equal(count1, 1);
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const unsubscribe = store.subscribe(() => count2 += 1);
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assert.equal(count2, 1);
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unsubscribe();
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});
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});
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describe('readable', () => {
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it('creates a readable store', () => {
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let running;
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let tick;
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const store = readable(undefined, set => {
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tick = set;
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running = true;
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set(0);
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return () => {
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tick = () => { };
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running = false;
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};
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});
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assert.ok(!running);
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const values = [];
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const unsubscribe = store.subscribe(value => {
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values.push(value);
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});
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assert.ok(running);
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tick(1);
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tick(2);
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unsubscribe();
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assert.ok(!running);
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tick(3);
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tick(4);
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assert.deepEqual(values, [0, 1, 2]);
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});
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});
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describe('derived', () => {
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it('maps a single store', () => {
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const a = writable(1);
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const b = derived(a, n => n * 2);
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const values = [];
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const unsubscribe = b.subscribe(value => {
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values.push(value);
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});
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a.set(2);
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assert.deepEqual(values, [2, 4]);
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unsubscribe();
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a.set(3);
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assert.deepEqual(values, [2, 4]);
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});
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it('maps multiple stores', () => {
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const a = writable(2);
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const b = writable(3);
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const c = derived(([a, b]), ([a, b]) => a * b);
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const values = [];
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const unsubscribe = c.subscribe(value => {
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values.push(value);
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});
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a.set(4);
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b.set(5);
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assert.deepEqual(values, [6, 12, 20]);
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unsubscribe();
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a.set(6);
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assert.deepEqual(values, [6, 12, 20]);
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});
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it('passes optional set function', () => {
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const number = writable(1);
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const evens = derived(number, (n, set) => {
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if (n % 2 === 0) set(n);
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}, 0);
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const values = [];
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const unsubscribe = evens.subscribe(value => {
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values.push(value);
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});
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number.set(2);
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number.set(3);
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number.set(4);
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number.set(5);
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assert.deepEqual(values, [0, 2, 4]);
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unsubscribe();
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number.set(6);
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number.set(7);
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number.set(8);
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assert.deepEqual(values, [0, 2, 4]);
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});
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it('prevents glitches', () => {
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const lastname = writable('Jekyll');
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const firstname = derived(lastname, n => n === 'Jekyll' ? 'Henry' : 'Edward');
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const fullname = derived([firstname, lastname], names => names.join(' '));
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const values = [];
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const unsubscribe = fullname.subscribe(value => {
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values.push(value);
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});
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lastname.set('Hyde');
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assert.deepEqual(values, [
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'Henry Jekyll',
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'Edward Hyde'
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]);
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unsubscribe();
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});
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it('prevents diamond dependency problem', () => {
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const count = writable(0);
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const values = [];
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const a = derived(count, $count => {
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return 'a' + $count;
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});
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const b = derived(count, $count => {
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return 'b' + $count;
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});
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const combined = derived([a, b], ([a, b]) => {
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return a + b;
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});
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const unsubscribe = combined.subscribe(v => {
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values.push(v);
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});
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assert.deepEqual(values, ['a0b0']);
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count.set(1);
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assert.deepEqual(values, ['a0b0', 'a1b1']);
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unsubscribe();
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});
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it('derived dependency does not update and shared ancestor updates', () => {
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const root = writable({ a: 0, b:0 });
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const values = [];
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const a = derived(root, $root => {
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return 'a' + $root.a;
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});
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const b = derived([a, root], ([$a, $root]) => {
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return 'b' + $root.b + $a;
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});
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const unsubscribe = b.subscribe(v => {
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values.push(v);
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});
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assert.deepEqual(values, ['b0a0']);
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root.set({ a: 0, b: 1 });
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assert.deepEqual(values, ['b0a0', 'b1a0']);
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unsubscribe();
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});
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it('is updated with safe_not_equal logic', () => {
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const arr = [0];
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const number = writable(1);
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const numbers = derived(number, $number => {
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arr[0] = $number;
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return arr;
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});
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const concatenated = [];
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const unsubscribe = numbers.subscribe(value => {
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concatenated.push(...value);
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});
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number.set(2);
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number.set(3);
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assert.deepEqual(concatenated, [1, 2, 3]);
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unsubscribe();
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});
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it('calls a cleanup function', () => {
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const num = writable(1);
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const values = [];
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const cleaned_up = [];
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const d = derived(num, ($num, set) => {
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set($num * 2);
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return function cleanup() {
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cleaned_up.push($num);
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};
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});
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num.set(2);
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const unsubscribe = d.subscribe(value => {
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values.push(value);
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});
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num.set(3);
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num.set(4);
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assert.deepEqual(values, [4, 6, 8]);
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assert.deepEqual(cleaned_up, [2, 3]);
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unsubscribe();
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assert.deepEqual(cleaned_up, [2, 3, 4]);
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});
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it('discards non-function return values', () => {
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const num = writable(1);
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const values = [];
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const d = derived(num, ($num, set) => {
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set($num * 2);
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return {};
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});
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num.set(2);
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const unsubscribe = d.subscribe(value => {
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values.push(value);
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});
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num.set(3);
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num.set(4);
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assert.deepEqual(values, [4, 6, 8]);
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unsubscribe();
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});
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it('allows derived with different types', () => {
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const a = writable('one');
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const b = writable(1);
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const c = derived([a, b], ([a, b]) => `${a} ${b}`);
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assert.deepEqual(get(c), 'one 1');
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a.set('two');
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b.set(2);
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assert.deepEqual(get(c), 'two 2');
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});
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});
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describe('get', () => {
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it('gets the current value of a store', () => {
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const store = readable(42, () => { });
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assert.equal(get(store), 42);
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});
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it('works with RxJS-style observables', () => {
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const observable = {
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subscribe(fn) {
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fn(42);
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return {
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unsubscribe: () => {}
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};
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}
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};
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assert.equal(get(observable), 42);
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});
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});
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});
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