Add useGetSetState tests

src/__tests__/useGetSet.test.ts

@@ -16,23 +16,23 @@ describe('useGetSet hook', () => {
     expect(set).toBeInstanceOf(Function);
   });
 
-  it('should get current state', () => {
+  it('should get current value', () => {
     const { result } = setUp('foo');
     const [get] = result.current;
 
-    const currentState = get();
+    const currentValue = get();
 
-    expect(currentState).toBe('foo');
+    expect(currentValue).toBe('foo');
   });
 
-  it('should set new state', () => {
+  it('should set new value', () => {
     const { result } = setUp('foo');
     const [get, set] = result.current;
 
     act(() => set('bar'));
 
-    const currentState = get();
-    expect(currentState).toBe('bar');
+    const currentValue = get();
+    expect(currentValue).toBe('bar');
   });
 
   /**
@@ -59,8 +59,8 @@ describe('useGetSet hook', () => {
       jest.runAllTimers();
     });
 
-    const currentState = get();
-    expect(currentState).toBe(3);
+    const currentValue = get();
+    expect(currentValue).toBe(3);
     expect(onClick).toHaveBeenCalledTimes(3);
   });
 });

src/__tests__/useGetSetState.test.ts

@@ -0,0 +1,127 @@
+import { act, renderHook } from '@testing-library/react-hooks';
+import useGetSetState from '../useGetSetState';
+
+const originalConsoleError = console.error;
+const mockConsoleError = jest.fn();
+
+describe('useGetSetState hook', () => {
+  const setUp = (initialState: any) => renderHook(() => useGetSetState(initialState));
+
+  beforeAll(() => {
+    console.error = mockConsoleError;
+  });
+
+  afterAll(() => {
+    console.error = originalConsoleError;
+  });
+
+  beforeEach(() => {
+    jest.useFakeTimers();
+  });
+
+  it('should init getter and setter', () => {
+    const { result } = setUp({ foo: 'initialValue' });
+    const [get, set] = result.current;
+
+    expect(get).toBeInstanceOf(Function);
+    expect(set).toBeInstanceOf(Function);
+  });
+
+  it('should log an error if init with something different than an object', () => {
+    expect(mockConsoleError).not.toHaveBeenCalled();
+
+    setUp('not an object');
+
+    expect(mockConsoleError).toHaveBeenCalledTimes(1);
+    expect(mockConsoleError).toHaveBeenCalledWith('useGetSetState initial state must be an object.');
+  });
+
+  it('should get current state', () => {
+    const { result } = setUp({ foo: 'a', bar: 'z' });
+    const [get] = result.current;
+
+    const currentState = get();
+
+    expect(currentState).toEqual({ foo: 'a', bar: 'z' });
+  });
+
+  it('should set new state by applying partial patch with existing keys', () => {
+    const { result } = setUp({ foo: 'a', bar: 'z' });
+    const [get, set] = result.current;
+
+    act(() => set({ bar: 'y' }));
+
+    const currentState = get();
+    expect(currentState).toEqual({ foo: 'a', bar: 'y' });
+  });
+
+  it('should set new state by applying partial patch with new keys', () => {
+    const { result } = setUp({ foo: 'a', bar: 'z' });
+    const [get, set] = result.current;
+
+    act(() => set({ qux: 'f' }));
+
+    const currentState = get();
+    expect(currentState).toEqual({ foo: 'a', bar: 'z', qux: 'f' });
+  });
+
+  it('should set new state by applying partial patch with both new and old keys', () => {
+    const { result } = setUp({ foo: 'a', bar: 'z' });
+    const [get, set] = result.current;
+
+    act(() => set({ bar: 'y', qux: 'f' }));
+
+    const currentState = get();
+    expect(currentState).toEqual({ foo: 'a', bar: 'y', qux: 'f' });
+  });
+
+  it('should NOT set new state if empty partial patch received', () => {
+    const { result } = setUp({ foo: 'a', bar: 'z' });
+    const [get, set] = result.current;
+
+    act(() => set({}));
+
+    const currentState = get();
+    expect(currentState).toEqual({ foo: 'a', bar: 'z' });
+  });
+
+  it('should log an error if set with a patch different than an object', () => {
+    const { result } = setUp({ foo: 'a', bar: 'z' });
+    const [, set] = result.current;
+    expect(mockConsoleError).not.toHaveBeenCalled();
+
+    // @ts-ignore
+    act(() => set('not an object'));
+
+    expect(mockConsoleError).toHaveBeenCalledTimes(1);
+    expect(mockConsoleError).toHaveBeenCalledWith('useGetSetState setter patch must be an object.');
+  });
+
+  /**
+   * This test is equivalent to demo one for `useGetSet` hook.
+   */
+  it('should get and set expected state when used in nested functions', () => {
+    const onClick = jest.fn(() => {
+      setTimeout(() => {
+        set({ counter: get().counter + 1 });
+      }, 1000);
+    });
+
+    const { result } = setUp({ counter: 0 });
+    const [get, set] = result.current;
+
+    // simulate 3 clicks
+    onClick();
+    onClick();
+    onClick();
+
+    // fast-forward until all timers have been executed
+    act(() => {
+      jest.runAllTimers();
+    });
+
+    const currentState = get();
+    expect(currentState).toEqual({ counter: 3 });
+    expect(onClick).toHaveBeenCalledTimes(3);
+  });
+});