description: "Simple overview of NocoDB architecture"
position: 3000
category: "Engineering"
menuTitle: "NocoDB architecture"
menuTitle: "Architecture Overview"
---
By default, if `NC_DB` is not specified, then SQLite will be used to store your meta data. We suggest users to separate the meta data and user data in different databases.
- MySQL is preferrable - however we fallback to SQLite
- We use [Mocha](https://mochajs.org/) as our test runner and [chai](https://www.chaijs.com/) as our assertion library.
- We use [Supertest](https://www.npmjs.com/package/supertest) to test our API endpoints.
## Setup
```
cp scripts/.env.copy scripts/.env
open scripts/.env
# Edit the following env variables
# `DB_USER` : mysql username
# `DB_PASSWORD` : mysql password
# `DB_HOST` : mysql host
# `DB_PORT` : mysql port
```
## How to run API tests
```
cd packages/nocodb
npm run test:unit
```
## Key points
- All individual unit tests are independent of each other. We don't use any shared state between tests.
- Test environment also includes `sakila` database and any change on `sakila` by a test is reverted before running other tests.
- Test environment includes `sakila` sample database and any change to it by a test is reverted before running other tests.
- While running unit tests, it tries to connect to mysql server running on `localhost:3306` with username `root` and password `password`(which can be configured) and if not found, it will use `sqlite` as a fallback, hence no requirement of any sql server to run tests.
## Walk through of writing a unit test
We will create an `Table` test suite as an example.
### Describing test suite
Create `Table` test suite by using `describe` function of mocha.
```typescript
export default function () {
describe('Table', tableTests);
}
```
### Configure test
@ -147,13 +155,5 @@ The root folder for unit tests is `packages/tests/unit`
- Use one file per factory.
## Using sakila db
To use sakila db use `createSakilaProject` from `factory/project` to create a project. This project will be seeded with `sakila` tables.
## Configurations
- For Mysql db configuration, use the following environment variables to configure.