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import React from 'react';
import { render, fireEvent } from '@testing-library/react';
import { act, renderHook } from '@testing-library/react-hooks';
import createReducerContext from '../src/factory/createReducerContext';
type Action = 'increment' | 'decrement';
const reducer = (state: number, action: Action) => {
switch (action) {
case 'increment':
return state + 1;
case 'decrement':
return state - 1;
default:
throw new Error();
}
};
it('should create a hook and a provider', () => {
const [useSharedNumber, SharedNumberProvider] = createReducerContext(reducer, 0);
expect(useSharedNumber).toBeInstanceOf(Function);
expect(SharedNumberProvider).toBeInstanceOf(Function);
});
describe('when using created hook', () => {
it('should throw out of a provider', () => {
const [useSharedNumber] = createReducerContext(reducer, 0);
const { result } = renderHook(() => useSharedNumber());
expect(result.error).toEqual(
new Error('useReducerContext must be used inside a ReducerProvider.')
);
});
const setUp = () => {
const [useSharedNumber, SharedNumberProvider] = createReducerContext(reducer, 0);
const wrapper = ({ children }: { children?: React.ReactNode }) => (
<SharedNumberProvider>{children}</SharedNumberProvider>
);
return renderHook(() => useSharedNumber(), { wrapper });
};
it('should init state and updater', () => {
const { result } = setUp();
const [sharedNumber, updateSharedNumber] = result.current;
expect(sharedNumber).toEqual(0);
expect(updateSharedNumber).toBeInstanceOf(Function);
});
it('should update the state', () => {
const { result } = setUp();
const [, updateSharedNumber] = result.current;
act(() => updateSharedNumber('increment'));
const [sharedNumber] = result.current;
expect(sharedNumber).toEqual(1);
});
});
describe('when using among multiple components', () => {
const [useSharedNumber, SharedNumberProvider] = createReducerContext(reducer, 0);
const DisplayComponent = () => {
const [sharedNumber] = useSharedNumber();
return <p>{sharedNumber}</p>;
};
const UpdateComponent = () => {
const [, updateSharedNumber] = useSharedNumber();
return (
<button type="button" onClick={() => updateSharedNumber('increment')}>
INCREMENT
</button>
);
};
it('should be in sync when under the same provider', () => {
const { baseElement, getByText } = render(
<SharedNumberProvider>
<DisplayComponent />
<DisplayComponent />
<UpdateComponent />
</SharedNumberProvider>
);
expect(baseElement.innerHTML).toBe(
'<div><p>0</p><p>0</p><button type="button">INCREMENT</button></div>'
);
fireEvent.click(getByText('INCREMENT'));
expect(baseElement.innerHTML).toBe(
'<div><p>1</p><p>1</p><button type="button">INCREMENT</button></div>'
);
});
it('should be in update independently when under different providers', () => {
const { baseElement, getByText } = render(
<>
<SharedNumberProvider>
<DisplayComponent />
</SharedNumberProvider>
<SharedNumberProvider>
<DisplayComponent />
<UpdateComponent />
</SharedNumberProvider>
</>
);
expect(baseElement.innerHTML).toBe(
'<div><p>0</p><p>0</p><button type="button">INCREMENT</button></div>'
);
fireEvent.click(getByText('INCREMENT'));
expect(baseElement.innerHTML).toBe(
'<div><p>0</p><p>1</p><button type="button">INCREMENT</button></div>'
);
});
it('should not update component that do not use the state context', () => {
let renderCount = 0;
const StaticComponent = () => {
renderCount++;
return <p>static</p>;
};
const { baseElement, getByText } = render(
<>
<SharedNumberProvider>
<StaticComponent />
<DisplayComponent />
<UpdateComponent />
</SharedNumberProvider>
</>
);
expect(baseElement.innerHTML).toBe(
'<div><p>static</p><p>0</p><button type="button">INCREMENT</button></div>'
);
fireEvent.click(getByText('INCREMENT'));
expect(baseElement.innerHTML).toBe(
'<div><p>static</p><p>1</p><button type="button">INCREMENT</button></div>'
);
expect(renderCount).toBe(1);
});
it('should override initialValue', () => {
const { baseElement } = render(
<>
<SharedNumberProvider>
<DisplayComponent />
</SharedNumberProvider>
<SharedNumberProvider initialState={15}>
<DisplayComponent />
</SharedNumberProvider>
</>
);
expect(baseElement.innerHTML).toBe('<div><p>0</p><p>15</p></div>');
});
});
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