Emoji Rendering Efficiency (#35568)

app/javascript/mastodon/utils/__tests__/cache.test.ts

@@ -0,0 +1,78 @@
+import { createLimitedCache } from '../cache';
+
+describe('createCache', () => {
+  test('returns expected methods', () => {
+    const actual = createLimitedCache();
+    expect(actual).toBeTypeOf('object');
+    expect(actual).toHaveProperty('get');
+    expect(actual).toHaveProperty('has');
+    expect(actual).toHaveProperty('delete');
+    expect(actual).toHaveProperty('set');
+  });
+
+  test('caches values provided to it', () => {
+    const cache = createLimitedCache();
+    cache.set('test', 'result');
+    expect(cache.get('test')).toBe('result');
+  });
+
+  test('has returns expected values', () => {
+    const cache = createLimitedCache();
+    cache.set('test', 'result');
+    expect(cache.has('test')).toBeTruthy();
+    expect(cache.has('not found')).toBeFalsy();
+  });
+
+  test('updates a value if keys are the same', () => {
+    const cache = createLimitedCache();
+    cache.set('test1', 1);
+    cache.set('test1', 2);
+    expect(cache.get('test1')).toBe(2);
+  });
+
+  test('delete removes an item', () => {
+    const cache = createLimitedCache();
+    cache.set('test', 'result');
+    expect(cache.has('test')).toBeTruthy();
+    cache.delete('test');
+    expect(cache.has('test')).toBeFalsy();
+    expect(cache.get('test')).toBeUndefined();
+  });
+
+  test('removes oldest item cached if it exceeds a set size', () => {
+    const cache = createLimitedCache({ maxSize: 1 });
+    cache.set('test1', 1);
+    cache.set('test2', 2);
+    expect(cache.get('test1')).toBeUndefined();
+    expect(cache.get('test2')).toBe(2);
+  });
+
+  test('retrieving a value bumps up last access', () => {
+    const cache = createLimitedCache({ maxSize: 2 });
+    cache.set('test1', 1);
+    cache.set('test2', 2);
+    expect(cache.get('test1')).toBe(1);
+    cache.set('test3', 3);
+    expect(cache.get('test1')).toBe(1);
+    expect(cache.get('test2')).toBeUndefined();
+    expect(cache.get('test3')).toBe(3);
+  });
+
+  test('logs when cache is added to and removed', () => {
+    const log = vi.fn();
+    const cache = createLimitedCache({ maxSize: 1, log });
+    cache.set('test1', 1);
+    expect(log).toHaveBeenLastCalledWith(
+      'Added %s to cache, now size %d',
+      'test1',
+      1,
+    );
+    cache.set('test2', 1);
+    expect(log).toHaveBeenLastCalledWith(
+      'Added %s and deleted %s from cache, now size %d',
+      'test2',
+      'test1',
+      1,
+    );
+  });
+});