TestingModule & Provider Overrides

TestingModule compiles a real module through the DI pipeline but lets you replace specific providers with mocks. This sits between a unit test (no framework) and a full e2e test (real providers).

Use it when you want to test a command's behavior through the full interaction pipeline, but you need to control what a service returns.

Usage

import { NodecordClient, TestingModule } from '@nodecord/core';
import { TestingDjsAdapter, createMockChatInputInteraction } from '@nodecord/djs-adapter/testing';
import { AdminModule } from './admin.module';
import { AdminService } from './admin.service';

describe('AdminModule', () => {
    const adminServiceMock = {
        getStatus: () => 'mocked status',
    };
    const adapter = new TestingDjsAdapter();

    beforeAll(() => {
        const testingModule = TestingModule.create(AdminModule)
            .overrideProvider(AdminService, adminServiceMock)
            .build();

        NodecordClient.create({
            module: testingModule,
            adapter,
            options: { logger: false },
        });
    });

    it('uses the mocked AdminService', async () => {
        const interaction = createMockChatInputInteraction({ commandName: 'admin' });
        await adapter.simulateInteraction(interaction);

        expect(interaction.deferReply).toHaveBeenCalledOnce();
        expect(interaction.editReply).toHaveBeenCalledWith({ content: 'Bot status: mocked status' });
    });
});

How it works

1. TestingModule.create(Module) - wraps the target module
2. .overrideProvider(ServiceClass, mockObject) - replaces the provider in the container before compilation
3. .build() - returns the compiled module
4. Pass it as module to NodecordClient.create() alongside a TestingDjsAdapter

If you only need to test a service's logic, instantiate it directly. Use TestingModule when you care about the full handler execution like interceptors, param decorators, and the adapter response.