> ## Documentation Index
> Fetch the complete documentation index at: https://docs.magnitude.run/llms.txt
> Use this file to discover all available pages before exploring further.

# Testing Setup

> Set up a Magnitude project and run an example

## Setup

<Steps>
  <Step title="Install our test library">
    ```sh theme={null}
    npm install --save-dev magnitude-test
    ```

    > or see our [demo repo](https://github.com/magnitudedev/magnitude-demo-repo) if you don't have a project to try it on
  </Step>

  <Step title="Initialize Magnitude">
    ```sh theme={null}
    npx magnitude init
    ```

    This will create a basic tests directory `tests/magnitude` with:

    * `magnitude.config.ts`: Magnitude test configuration file
    * `example.mag.ts`: An example test file
  </Step>

  <Step title="Configure LLM">
    The easiest way to set up an LLM for Magnitude is to set the `ANTHROPIC_API_KEY` environment variable. Sonnet 4 will be used by default. See [LLM Configuration](/customizing/llm-configuration) for more details.
  </Step>
</Steps>

🚀 Now you're ready to run tests!

## Running tests

**Run your Magnitude tests with:**

```sh theme={null}
npx magnitude
```

This will run all Magnitude test files discovered with the `*.mag.ts` pattern. If the agent finds a problem with your app, it will tell you what happened and describe the bug!

> To run many tests in parallel, add `-w <workers>`

To learn more about different options for running tests see [here](/testing/running-tests).

## Building test cases

Now that you've got Magnitude set up, you can create real test cases for your app. Here's an example for a general idea:

```ts theme={null}
import { test } from 'magnitude-test';

test('can log in and create company', async (agent) => {
    await agent.act('Log in to the app', {
        data: { username: 'test-user@magnitude.run', password: 'test' }
    });
    await agent.check('Can see dashboard');
    await agent.act('Create a new company', { data: 'Make up the first 2 values and use defaults for the rest' });
    await agent.check('Company added successfully');
});
```

Acts, checks, and data are all natural language. Think of it like you're describing how to test a particular flow to a co-worker - what steps they need to take, what they should check for, and what test data to use.

For more information on how to build test cases see <a href="https://docs.magnitude.run/core-concepts/building-test-cases" target="_blank">our docs.</a>