Initial commit

tests/unit/infrastructure/AsyncLazy.spec.ts

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+import { AsyncLazy } from '@/infrastructure/Threading/AsyncLazy';
+import 'mocha';
+import { expect } from 'chai';
+
+describe('AsyncLazy', () => {
+
+    it('returns value from lambda', async () => {
+        // arrange
+        const expected = 'test';
+        const lambda = () => Promise.resolve(expected);
+        const sut = new AsyncLazy(lambda);
+
+        // act
+        const actual = await sut.getValueAsync();
+
+        // assert
+        expect(actual).to.equal(expected);
+    });
+
+    describe('when running multiple times', () => {
+        let totalExecuted: number = 0;
+
+        beforeEach(() => totalExecuted = 0);
+
+        it('when running sync', async () => {
+            const sut = new AsyncLazy(() => {
+                totalExecuted++;
+                return Promise.resolve(totalExecuted);
+            });
+            const results = new Array<number>();
+            for (let i = 0; i < 5; i++) {
+                results.push(await sut.getValueAsync());
+            }
+            expect(totalExecuted).to.equal(1);
+            expect(results).to.deep.equal([1, 1, 1, 1, 1]);
+        });
+
+        it('when running long-running task paralelly', async () => {
+            const sleep = (time: number) => new Promise(((resolve) => setTimeout(resolve, time)));
+            const sut = new AsyncLazy(async () => {
+                await sleep(100);
+                totalExecuted++;
+                return Promise.resolve(totalExecuted);
+            });
+            const results = await Promise.all([
+                sut.getValueAsync(),
+                sut.getValueAsync(),
+                sut.getValueAsync(),
+                sut.getValueAsync(),
+                sut.getValueAsync()]);
+            expect(totalExecuted).to.equal(1);
+            expect(results).to.deep.equal([1, 1, 1, 1, 1]);
+        });
+    });
+});