# `@oaklean/jest-profiler-environment`
A jest environment to collect energy measurements on source code level during test execution.
Supports Jest versions 28 & 29.
## Usage
#### 1. Installation
`npm add --save-dev @oaklean/profiler-jest-environment`
#### 2. Add the `@oaklean/jest-profiler-environment` to the jest config
Adjust the jest config like this:
```javascript
module.exports = {
...
testEnvironment: '@oaklean/profiler-jest-environment/env.js', // add this line
globalSetup: '@oaklean/profiler-jest-environment/setup.js', // add this line
globalTeardown: '@oaklean/profiler-jest-environment/teardown.js', // add this line
...
}
```
#### 3. Create a `.oaklean` config file
The `@oaklean/cli` can be used to easily setup a `.oaklean` config file.
1. Install the cli: `npm add --save-dev @oaklean/cli`
2. Run the init script: `npx oak init`
3. It will ask you which sensor interface should be used for energy measurements:
```
Select a sensor interface (recommended for your platform: perf)
None (pure cpu time measurements)
powermetrics (macOS only)
❯ perf (Linux only)
windows (Windows only)
energy measurements on Linux (Intel & AMD CPUs only)
```
4. The cli asks you to confirm your choice and generates a valid `.oaklean` config file for you:
```
? Select a sensor interface (recommended for your platform: perf) perf (Linux only)
{
"exportOptions": {
"outDir": "profiles/",
"outHistoryDir": "profiles_history/",
"rootDir": "./",
"exportV8Profile": false,
"exportReport": true,
"exportSensorInterfaceData": false
},
"projectOptions": {
"identifier": "XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX"
},
"runtimeOptions": {
"seeds": {},
"v8": {
"cpu": {
"sampleInterval": 1
}
},
"sensorInterface": {
"type": "perf",
"options": {
"outputFilePath": "energy-measurements.txt",
"sampleInterval": 100
}
}
}
}
? Is this OK? (yes) (Y/n)
```
##### Available Sensor Interfaces
| SensorInterface | Operating System |
| --------------- | ---------------- |
| powermetrics | macOS |
| perf | linux |
| windows | windows |
If you want to how to setup the Sensor Interfaces and how to make them work with **Docker** you can read more about it [here](/docs/SensorInterfaces.md)
> :warning: **Most Sensor Interfaces need root privileges**
> Look into the [Sensor Interface Docs](/docs/SensorInterfaces.md) to see how you can run them without root privileges
> :mag: **How measurements work**
> During the test execution measurements are collected with a sample based approach. So for every n - microseconds it collects a v8 cpu profile and energy measurements of the sensor interface. You can adjust the sampling rate with the `sampleInterval` options in the `.oaklean` config file above.
#### 4. Run the tests to collect energy measurements
> :warning: **The measurement data is NOT automatically collected**
To enable measurements during test execution you must set an environment variable beforehand (ENABLE_MEASUREMENTS=1).
When running Jest tests with this environment variable, the measurement data should be saved in the specified output directory.
> :pinched_fingers: **For more accurate measurement results**
It is mandatory to run Jest with the --runInBand option. This ensures that the tests are executed sequentially and not in different threads: npx jest --coverage --runInBand.
Execute the tests:
`ENABLE_MEASUREMENTS=1 npx jest --coverage --runInBand`
#### 5. Interpret the measurements and determine the source code locations with the most energy consumption
The `Oaklean` VSCode Extension lets you to interpret the measurements. It integrates the energy measurements directly into your IDE.
**You can find it here:**
- Github
- VS Code Extension
It provides code highlighting to point out which source code locations consume the most energy:
It also provides multiple features to determine the components that consume the most energy, including node modules:
