How to unit test Discord bot commands with Jest?

Other Questions Discord bot
1

I’m working on a Discord bot and want to use Jest for testing. My bot has a file with module exports, including an execute function that takes two arguments. This function doesn’t return anything, but it uses Discord.js to send a message like this:

message.channel.send('Pong');

I’m not sure how to test this properly. My main questions are:

  1. How can I check if message.channel.send was called with ‘Pong’?
  2. What’s the best way to mock this function without actually calling it?

I can run the command, but I’m stuck on how to verify the contents of message.channel.send. I can’t recreate the message object, so that might need mocking too.

Also, some of my commands return values. How should I approach testing those?

Any tips or examples would be super helpful. Thanks!

2

I’ve been through this exact scenario with my Discord bot! Here’s what worked for me:

For commands that don’t return values but send messages, mocking is your best friend. I used Jest’s mock functions to replace message.channel.send. Something like:

const mockSend = jest.fn();
const mockMessage = { channel: { send: mockSend } };

// Call your command function
await yourCommand.execute(mockMessage, []);

// Assert the mock was called correctly
expect(mockSend).toHaveBeenCalledWith('Pong');

For commands that return values, it’s more straightforward. Just call the function and assert on the return value.

One tip: create a helper function to set up your mocks. It’ll save you tons of boilerplate across your tests.

Remember to reset your mocks between tests to avoid false positives. Jest’s beforeEach() is great for this.

Hope this helps! Let me know if you need any clarification.

3

Having worked extensively with Discord bots and Jest, I can offer some insights.

For testing commands that send messages, mocking is crucial. Create a mock function for message.channel.send and a mock message object like this:

const mockSend = jest.fn();
const mockMessage = { channel: { send: mockSend } };

await yourCommand.execute(mockMessage, []);
expect(mockSend).toHaveBeenCalledWith('Pong');

For commands that return values, test the return value directly:

const result = await yourCommand.execute(mockMessage, []);
expect(result).toBe(expectedValue);

Centralizing your mocks in a setupTest.js file and resetting them between tests can greatly improve testing efficiency and reliability.

4

hey mate, i’ve been messing with discord bots too. for testing, try mocking message.channel.send with jest.fn(). then u can check if it was called with the right stuff. like:

const mockSend = jest.fn();
const fakeMsg = { channel: { send: mockSend } };
await command.execute(fakeMsg, []);
expect(mockSend).toHaveBeenCalledWith('Pong');

hope that helps!