wip: code formatting nits continued

test/memoize.spec.js

@@ -0,0 +1,175 @@
+import lodashStable from 'lodash';
+import { noop, stubTrue, identity } from './utils';
+import memoize from '../src/memoize';
+import isFunction from '../src/isFunction';
+
+describe('memoize', () => {
+    function CustomCache() {
+        this.clear();
+    }
+
+    CustomCache.prototype = {
+        clear: function () {
+            this.__data__ = [];
+            return this;
+        },
+        get: function (key) {
+            const entry = lodashStable.find(this.__data__, ['key', key]);
+            return entry && entry.value;
+        },
+        has: function (key) {
+            return lodashStable.some(this.__data__, ['key', key]);
+        },
+        set: function (key, value) {
+            this.__data__.push({ key: key, value: value });
+            return this;
+        },
+    };
+
+    function ImmutableCache() {
+        this.__data__ = [];
+    }
+
+    ImmutableCache.prototype = lodashStable.create(CustomCache.prototype, {
+        constructor: ImmutableCache,
+        clear: function () {
+            return new ImmutableCache();
+        },
+        set: function (key, value) {
+            const result = new ImmutableCache();
+            result.__data__ = this.__data__.concat({ key: key, value: value });
+            return result;
+        },
+    });
+
+    it('should memoize results based on the first argument given', () => {
+        const memoized = memoize((a, b, c) => a + b + c);
+
+        expect(memoized(1, 2, 3)).toBe(6);
+        expect(memoized(1, 3, 5)).toBe(6);
+    });
+
+    it('should support a `resolver`', () => {
+        const fn = function (a, b, c) {
+            return a + b + c;
+        };
+        const memoized = memoize(fn, fn);
+
+        expect(memoized(1, 2, 3)).toBe(6);
+        expect(memoized(1, 3, 5)).toBe(9);
+    });
+
+    it('should use `this` binding of function for `resolver`', () => {
+        const fn = function (a, b, c) {
+            return a + this.b + this.c;
+        };
+        const memoized = memoize(fn, fn);
+
+        const object = { memoized: memoized, b: 2, c: 3 };
+        expect(object.memoized(1)).toBe(6);
+
+        object.b = 3;
+        object.c = 5;
+        expect(object.memoized(1)).toBe(9);
+    });
+
+    it('should throw a TypeError if `resolve` is truthy and not a function', () => {
+        assert.throws(() => {
+            memoize(noop, true);
+        }, TypeError);
+    });
+
+    it('should not error if `resolver` is nullish', () => {
+        const values = [, null, undefined];
+        const expected = lodashStable.map(values, stubTrue);
+
+        const actual = lodashStable.map(values, (resolver, index) => {
+            try {
+                return isFunction(index ? memoize(noop, resolver) : memoize(noop));
+            } catch (e) {}
+        });
+
+        expect(actual).toEqual(expected);
+    });
+
+    it('should check cache for own properties', () => {
+        const props = [
+            'constructor',
+            'hasOwnProperty',
+            'isPrototypeOf',
+            'propertyIsEnumerable',
+            'toLocaleString',
+            'toString',
+            'valueOf',
+        ];
+
+        const memoized = memoize(identity);
+
+        const actual = lodashStable.map(props, (value) => memoized(value));
+
+        expect(actual).toEqual(props);
+    });
+
+    it('should cache the `__proto__` key', () => {
+        const array = [];
+        const key = '__proto__';
+
+        lodashStable.times(2, (index) => {
+            let count = 0;
+            const resolver = index ? identity : undefined;
+
+            const memoized = memoize(() => {
+                count++;
+                return array;
+            }, resolver);
+
+            const cache = memoized.cache;
+
+            memoized(key);
+            memoized(key);
+
+            expect(count).toBe(1);
+            expect(cache.get(key)).toBe(array);
+            expect(cache.__data__ instanceof Array).toBe(false);
+            expect(cache.delete(key)).toBe(true);
+        });
+    });
+
+    it('should allow `_.memoize.Cache` to be customized', () => {
+        const oldCache = memoize.Cache;
+        memoize.Cache = CustomCache;
+
+        const memoized = memoize((object) => object.id);
+
+        const cache = memoized.cache;
+        const key1 = { id: 'a' };
+        const key2 = { id: 'b' };
+
+        expect(memoized(key1)).toBe('a');
+        expect(cache.has(key1)).toBe(true);
+
+        expect(memoized(key2)).toBe('b');
+        expect(cache.has(key2)).toBe(true);
+
+        memoize.Cache = oldCache;
+    });
+
+    it('should works with an immutable `_.memoize.Cache` ', () => {
+        const oldCache = memoize.Cache;
+        memoize.Cache = ImmutableCache;
+
+        const memoized = memoize((object) => object.id);
+
+        const key1 = { id: 'a' };
+        const key2 = { id: 'b' };
+
+        memoized(key1);
+        memoized(key2);
+
+        const cache = memoized.cache;
+        expect(cache.has(key1)).toBe(true);
+        expect(cache.has(key2)).toBe(true);
+
+        memoize.Cache = oldCache;
+    });
+});