Testing QuickState

Testing is a critical part of the development process, ensuring that your state management logic works as expected. This document will guide you through setting up your testing environment and writing tests for your QuickState-based application.

Setting Up Your Test Environment

To start testing your QuickState application, you'll need to set up your testing environment. Here's how you can do it:

1. Install your preferred testing framework (e.g., Jest, Mocha).
2. Set up a test runner and configure it to work with your project structure.
3. Install any additional assertion libraries or testing utilities you may need.

Example using Jest:

npm install --save-dev jest @testing-library/react @testing-library/user-event @testing-library/dom

Add a Jest configuration file to your project, or add the Jest configuration to your package.json.

For additional information on configuration, kindly refer to the Jest documentation.

Writing Tests

When writing tests for QuickState, you'll be testing the following:

• Actions: Ensure that actions modify the state as expected.
• Selectors: Validate that selectors return the correct slice of state.
• Store: Confirm that the store updates correctly in response to actions.

Testing Actions

Actions should be tested to ensure they produce the expected state mutations. Here's an example of how to test an action:

TypeScript

import {increaseCount} from "../actions";
import {store, MyState} from "../store";

describe("increaseCount action", () => {
    const initialState: MyState = {
        count: 0,
    };

    beforeEach(() => {
        store.setState(initialState);
    });

    test("should initialize with the correct state", () => {
        expect(store.getState()).toEqual(initialState);
    });

    test("should increase count by 1", () => {
        increaseCount();
        expect(store.getState().count).toBe(initialState.count + 1);
    });

    test("should handle multiple increaseCount actions", () => {
        increaseCount();
        increaseCount();
        expect(store.getState().count).toBe(initialState.count + 2);
    });
});

JavaScript

import {increaseCount} from "../actions";
import {store} from "../store";

describe("increaseCount action", () => {
	const initialState = {
		count: 0,
	};

	beforeEach(() => {
		store.setState(initialState);
	});

	test("should initialize with the correct state", () => {
		expect(store.getState()).toEqual(initialState);
	});

	test("should increase count by 1", () => {
		increaseCount();
		expect(store.getState().count).toBe(initialState.count + 1);
	});

	test("should handle multiple increaseCount actions", () => {
		increaseCount();
		increaseCount();
		expect(store.getState().count).toBe(initialState.count + 2);
	});
});

Testing Selectors

Selectors should be tested to verify that they compute and return the right data from the state. Consider the following example:

TypeScript

import {countSelector} from "./select-count";
import {store, MyState} from "../store";

describe("selectCount selector", () => {
    const initialState = {
        count: 0,
    };

    beforeEach(() => {
        store.setState(initialState);
    });

    it("should return the current count from state", () => {
        expect(countSelector(store.getState())).toBe(0);
    });

    it("should return the updated count when state changes", () => {
        store.setState({
            count: 10,
        });

        expect(countSelector(store.getState())).toBe(10);
    });
});

JavaScript

import {countSelector} from "./select-count";
import {store, MyState} from "../store";

describe("selectCount selector", () => {
    const initialState = {
        count: 0,
    };
    
    beforeEach(() => {
        store.setState(initialState);
    });
    
    it("should return the current count from state", () => {
		expect(countSelector(store.getState())).toBe(0);
    });
    
    it("should return the updated count when state changes", () => {
        store.setState({
            count: 10,
        });

		expect(countSelector(store.getState())).toBe(10);
    });
});

Integration with UI Components

Testing UI components that are connected to the QuickState store involves:

1. Rendering the components within a test environment.
2. Dispatching actions and verifying that the UI updates accordingly.
3. Checking that selectors are providing the right props to the components.

Example with a Counter Component:

TypeScript

import React from "react";
import {render, fireEvent} from "@testing-library/react";
import {Counter} from "./counter";
import {IncrementButton} from "./increment-button";
import {MyStoreProvider} from "./state";

test("Counter component shows the count and can be incremented", () => {
    const {getByText} = render(
        <MyStoreProvider>
            <Counter />
            <IncrementButton />
        </MyStoreProvider>
    );

    expect(getByText("Speed: 0")).toBeInTheDocument();
    fireEvent.click(getByText("Increment"));
    expect(getByText("Speed: 1")).toBeInTheDocument();
});

JavaScript

import React from "react";
import {render, fireEvent} from "@testing-library/react";
import {Counter} from "./counter";
import {IncrementButton} from "./increment-button";
import {MyStoreProvider} from "./state";

test("Counter component shows the count and can be incremented", () => {
    const {getByText} = render(
        <MyStoreProvider>
            <Counter />
            <IncrementButton />
        </MyStoreProvider>
    );
    
    expect(getByText("Speed: 0")).toBeInTheDocument();
    fireEvent.click(getByText("Increment"));
    expect(getByText("Speed: 1")).toBeInTheDocument();
});

Continuous Integration

Integrate your tests into a CI/CD pipeline to ensure they run automatically with every push or pull request. This helps catch issues early and maintain a stable codebase.

Conclusion

Testing your state management effectively ensures the reliability of your application's data flow. By following the principles outlined above, you can create a robust suite of tests for your QuickState-powered applications.