Add Cache Wrapper tests

superset-frontend/spec/javascripts/utils/cacheWrapper_spec.ts

@@ -0,0 +1,83 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+import { cacheWrapper } from 'src/utils/cacheWrapper';
+
+describe('cacheWrapper', () => {
+  const fnResult = 'fnResult';
+  const fn = jest.fn<string, [number, number]>().mockReturnValue(fnResult);
+
+  let wrappedFn: (a: number, b: number) => string;
+
+  beforeEach(() => {
+    const cache = new Map<string, any>();
+    wrappedFn = cacheWrapper(fn, cache);
+  });
+
+  afterEach(() => {
+    jest.clearAllMocks();
+  });
+
+  it('calls fn with its arguments once when the key is not found', () => {
+    const returnedValue = wrappedFn(1, 2);
+
+    expect(returnedValue).toEqual(fnResult);
+    expect(fn).toBeCalledTimes(1);
+    expect(fn).toBeCalledWith(1, 2);
+  });
+
+  describe('subsequent calls', () => {
+    it('returns the correct value without fn being called multiple times', () => {
+      const returnedValue1 = wrappedFn(1, 2);
+      const returnedValue2 = wrappedFn(1, 2);
+
+      expect(returnedValue1).toEqual(fnResult);
+      expect(returnedValue2).toEqual(fnResult);
+      expect(fn).toBeCalledTimes(1);
+    });
+
+    it('fn is called multiple times for different arguments', () => {
+      wrappedFn(1, 2);
+      wrappedFn(1, 3);
+
+      expect(fn).toBeCalledTimes(2);
+    });
+  });
+
+  describe('with custom keyFn', () => {
+    let cache: Map<string, any>;
+
+    beforeEach(() => {
+      cache = new Map<string, any>();
+      wrappedFn = cacheWrapper(fn, cache, (...args) => `key-${args[0]}`);
+    });
+
+    it('saves fn result in cache under generated key', () => {
+      wrappedFn(1, 2);
+      expect(cache.get('key-1')).toEqual(fnResult);
+    });
+
+    it('subsequent calls with same generated key calls fn once, even if other arguments have changed', () => {
+      wrappedFn(1, 1);
+      wrappedFn(1, 2);
+      wrappedFn(1, 3);
+
+      expect(fn).toBeCalledTimes(1);
+    });
+  });
+});