Local Development of Medusa Backend and Monorepo
In this document, you’ll learn how to customize Medusa’s core and run tests.
As an open-source platform, Medusa’s core can be completely customized.
Whether you want to implement something differently, introduce a new feature as part of Medusa’s core or any of the other packages, or contribute to Medusa, this guide helps you learn how to run Medusa’s integration tests, as well as test your own Medusa core in a local backend.
Medusa Repository Overview
Medusa’s repository on GitHub includes all packages related to Medusa under the
packages directory. This includes the core Medusa package, the JS Client, the CLI tools, and much more.
All the packages are part of a Yarn workspace. So, when you run a command in the root of the project, such as
yarn build, it goes through all registered packages in the workspace under the
packages directory and runs the
build command in each of those packages.
When using and developing with the Medusa repository, it’s highly recommended that you use Yarn to avoid any errors or issues.
Fork and Clone Medusa’s Repository
To customize Medusa’s core or contribute to it, you must first fork and then clone the GitHub repository.
Install Dependencies and Build Packages
In the directory of the forked GitHub repository, run the following commands to install necessary dependencies then build all packages in the repository:
Medusa’s Dev CLI tool
Medusa provides a CLI tool to be used for development. This tool facilitates testing your local installment and changes to Medusa’s core without having to publish the changes to NPM.
To install Medusa’s dev CLI tool:
Set the Location of the Medusa Repository
In the directory of your forked GitHub repository, run the following command to specify to the dev CLI tool the location of your Medusa repository:
Run Tests in the Repository
In this section, you’ll learn how to run tests in the Medusa repository. This is helpful after you customize any of Medusa’s packages and want to make sure everything is still working as expected.
Set System Environment Variables
Before you can run the tests, make sure you set the following system environment variables:
Run Unit Tests
To run unit tests in all packages in the Medusa repository, run the following command in the root directory of the repository:
This runs the
test script defined in the
package.json file of each package under the
Alternatively, if you want to run the unit tests in a specific package, you can run the
test command in the directory of that package.
For example, to run the unit tests of the Medusa core:
Run API Integration Tests
API integration tests are used to test out Medusa’s core endpoints.
To run the API integration tests, run the following command in the root directory of the repository:
Run Plugin Integration Tests
Plugin integration tests are used to test out Medusa’s official plugins, which are also stored in the
packages directory in the repository.
To run the plugin integration tests, run the following command in the root directory of the repository:
Test in a Local Backend
Using Medusa’s dev CLI tool, you can test any changes you make to Medusa’s packages in a local backend installation. This eliminates the need to publish these packages on NPM publicly to be able to use them.
Medusa’s dev CLI tool scans and finds the Medusa packages used in your Medusa backend. Then, it copies the files of these packages from the
packages directory in the Medusa repository into the
node_modules directory of your Medusa backend.
Copy Files to Local Backend
To test in a local backend:
- Change to the directory of the backend you want to test your changes in:
2. Run the following command to copy the files from the
packages directory of your Medusa repository into
By default, Medusa’s dev CLI runs in watch mode. So, it copies the files when you first run it. Then, whenever you make changes in the
dist directory of the packages in the Medusa repository, it copies the changed files again.
Watch and Compile Changes
While the above command is running, it's recommended to run the
watch command inside the directory of every package you're making changes to.
The combination of these two commands running at the same time will compile the package into the
dist directory of the package, then copy the compiled changes into your local backend.
For example, if you're making changes in the
medusa package, run the following command inside the directory of the
Make sure the
medusa-dev command is also running to copy the changes automatically.
Alternatively, you can manually run the
build command every time you want to compile the changes:
Here are some options you can use to customize how Medusa’s dev CLI tool works:
-s: Copies files only one time then stops processing. If you make any changes after running the command with this option, you have to run the command again.
-q: Disables showing any output.
--packages: Only copies specified packages. It accepts at least one package name. Package names are separated by a space.