metamask-extension/development/README.md

# Development

Several files which are needed for developing on MetaMask.

Usually each file or directory contains information about its scope / usage.

## Segment

### Debugging with the Mock Segment API

To start the [Mock Segment API](./mock-segment.js):

-   Add/replace the `SEGMENT_HOST` and `SEGMENT_WRITE_KEY` variables in `.metamaskrc`
    ```
    SEGMENT_HOST='http://localhost:9090'
    SEGMENT_WRITE_KEY='FAKE'
    ```
-   Build the project to the `./dist/` folder with `yarn dist`
-   Run the Mock Segment API from the command line
    ```
    node development/mock-segment.js
    ```

Events triggered whilst using the extension will be logged to the console of the Mock Segment API.

More information on the API and its usage can be found [here](./mock-segment.js#L28).

### Debugging in Segment

To debug in a production Segment environment:

- Create a free account on [Segment](https://segment.com/)
- Create a New Workspace
- Add a Source (Node.js)
- Copy the `Write Key` from the API Keys section under Settings
-   Add/replace the `SEGMENT_HOST` and `SEGMENT_WRITE_KEY` variables in `.metamaskrc`
    ```
    SEGMENT_HOST='https://api.segment.io'
    SEGMENT_WRITE_KEY='COPIED_WRITE_KEY'
    ```
-   Build the project to the `./dist/` folder with `yarn dist`

Events triggered whilst using the extension will be displayed in Segment's Debugger.

### Debugging Segment requests in MetaMask

To opt in to MetaMetrics;
- Unlock the extension
- Open the Account menu 
- Click the `Settings` menu item
- Click the `Security & Privacy` menu item
- Toggle the `Participate in MetaMetrics` menu option to the `ON` position

You can inspect the requests in the `Network` tab of your browser's Developer Tools (background.html)
by filtering for `POST` requests to `/v1/batch`. The full url will be `http://localhost:9090/v1/batch`
or `https://api.segment.io/v1/batch` respectively.