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ts/test-both/util/memoizeByRoot.ts

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+// Copyright 2021 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+import { assert } from 'chai';
+import * as sinon from 'sinon';
+
+import { memoizeByRoot } from '../../util/memoizeByRoot';
+
+class Root {}
+
+describe('memoizeByRoot', () => {
+  it('should memoize by last passed arguments', () => {
+    const root = new Root();
+
+    const stub = sinon.stub();
+    stub.withArgs(sinon.match.same(root), 1).returns(1);
+    stub.withArgs(sinon.match.same(root), 2).returns(2);
+
+    const fn = memoizeByRoot(stub);
+
+    assert.strictEqual(fn(root, 1), 1);
+    assert.strictEqual(fn(root, 1), 1);
+    assert.isTrue(stub.calledOnce);
+
+    assert.strictEqual(fn(root, 2), 2);
+    assert.strictEqual(fn(root, 2), 2);
+    assert.isTrue(stub.calledTwice);
+
+    assert.strictEqual(fn(root, 1), 1);
+    assert.strictEqual(fn(root, 1), 1);
+    assert.isTrue(stub.calledThrice);
+  });
+
+  it('should memoize results by root', () => {
+    const rootA = new Root();
+    const rootB = new Root();
+
+    const stub = sinon.stub();
+    stub.withArgs(sinon.match.same(rootA), 1).returns(1);
+    stub.withArgs(sinon.match.same(rootA), 2).returns(2);
+    stub.withArgs(sinon.match.same(rootB), 1).returns(3);
+    stub.withArgs(sinon.match.same(rootB), 2).returns(4);
+
+    const fn = memoizeByRoot(stub);
+
+    assert.strictEqual(fn(rootA, 1), 1);
+    assert.strictEqual(fn(rootB, 1), 3);
+    assert.strictEqual(fn(rootA, 1), 1);
+    assert.strictEqual(fn(rootB, 1), 3);
+    assert.isTrue(stub.calledTwice);
+
+    assert.strictEqual(fn(rootA, 2), 2);
+    assert.strictEqual(fn(rootB, 2), 4);
+    assert.strictEqual(fn(rootA, 2), 2);
+    assert.strictEqual(fn(rootB, 2), 4);
+    assert.strictEqual(stub.callCount, 4);
+
+    assert.strictEqual(fn(rootA, 1), 1);
+    assert.strictEqual(fn(rootB, 1), 3);
+    assert.strictEqual(stub.callCount, 6);
+  });
+});