test(json-crdt): 💍 add fanout tests

Author: streamich

src/json-crdt/model/api/__tests__/fanout.spec.ts

@@ -0,0 +1,114 @@
+import {MapFanOut, MergeFanOut, MicrotaskBufferFanOut, OnNewFanOut} from '../fanout';
+import {FanOut} from 'thingies/es2020/fanout';
+
+describe('MergeFanOut', () => {
+  test('merges data from multiple fanouts', () => {
+    const fanout1 = new FanOut<number>();
+    const fanout2 = new FanOut<number>();
+    const fanout3 = new FanOut<number>();
+    const merged = new MergeFanOut<number>([fanout1, fanout2, fanout3]);
+    const data: number[] = [];
+    const unsub = merged.listen((d) => data.push(d));
+    fanout1.emit(1);
+    fanout2.emit(2);
+    fanout3.emit(3);
+    expect(data).toEqual([1, 2, 3]);
+    unsub();
+    fanout1.emit(1);
+    fanout2.emit(2);
+    fanout3.emit(3);
+    expect(data).toEqual([1, 2, 3]);
+    merged.listen((d) => data.push(d));
+    fanout3.emit(3);
+    fanout2.emit(2);
+    fanout1.emit(1);
+    expect(data).toEqual([1, 2, 3, 3, 2, 1]);
+  });
+});
+
+describe('MicrotaskBufferFanOut', () => {
+  test('buffers multiple emissions by microtask', async () => {
+    const source = new FanOut<number>();
+    const merged = new MicrotaskBufferFanOut<number>(source);
+    const data: number[][] = [];
+    const unsub = merged.listen((d) => data.push(d));
+    expect(data.length).toBe(0);
+    source.emit(1);
+    source.emit(2);
+    source.emit(3);
+    expect(data.length).toBe(0);
+    await Promise.resolve();
+    expect(data).toEqual([[1, 2, 3]]);
+    source.emit(1);
+    source.emit(2);
+    source.emit(3);
+    unsub();
+    source.emit(1);
+    source.emit(2);
+    source.emit(3);
+    await Promise.resolve();
+    expect(data).toEqual([[1, 2, 3]]);
+    merged.listen((d) => data.push(d));
+    source.emit(1);
+    source.emit(2);
+    source.emit(3);
+    await Promise.resolve();
+    expect(data).toEqual([
+      [1, 2, 3],
+      [1, 2, 3],
+    ]);
+  });
+});
+
+describe('MapFanOut', () => {
+  test('can multiply all values by 2x', () => {
+    const source = new FanOut<number>();
+    const merged = new MapFanOut<number, number>(source, (x) => x * 2);
+    const data: number[] = [];
+    const unsub = merged.listen((d) => data.push(d));
+    expect(data.length).toBe(0);
+    source.emit(1);
+    source.emit(2);
+    source.emit(3);
+    expect(data.length).toBe(3);
+    expect(data).toEqual([2, 4, 6]);
+    unsub();
+    source.emit(1);
+    source.emit(2);
+    source.emit(3);
+    expect(data.length).toBe(3);
+    merged.listen((d) => data.push(d));
+    source.emit(4);
+    expect(data).toEqual([2, 4, 6, 8]);
+  });
+});
+
+describe('OnNewFanOut', () => {
+  test('emits only new value changes', () => {
+    const obj1 = {};
+    const obj2 = {};
+    const source = new FanOut<any>();
+    const merged = new OnNewFanOut<any>(source);
+    const data: any[] = [];
+    const unsub = merged.listen((d) => data.push(d));
+    expect(data.length).toBe(0);
+    source.emit(obj1);
+    expect(data.length).toBe(1);
+    expect(data).toEqual([obj1]);
+    source.emit(obj1);
+    expect(data.length).toBe(1);
+    source.emit(obj2);
+    source.emit(obj2);
+    expect(data.length).toBe(2);
+    expect(data).toEqual([obj1, obj2]);
+    unsub();
+    source.emit(obj1);
+    source.emit(obj2);
+    expect(data.length).toBe(2);
+    expect(data).toEqual([obj1, obj2]);
+    merged.listen((d) => data.push(d));
+    source.emit(obj2);
+    expect(data.length).toBe(3);
+    expect(data).toEqual([obj1, obj2, obj2]);
+  });
+});