fix!: environment variable priority

CONTRIBUTING.md

@@ -124,6 +124,28 @@ pub enum SortBy {
 }
 ```
 
+## Tests
+
+To run all tests, use:
+```bash
+pixi run test
+```
+But if you have modified recipe data under the tests/data/channels directory, you need to update the test channel before running tests:
+```bash
+pixi run update-test-channel <channel_name>
+```
+> [!NOTE]
+> This task currently only works on unix systems. If you are on Windows, it is recommended to use [WSL](https://learn.microsoft.com/en-us/windows/wsl/install).
+
+For example, if you modified data for dummy_channel_1:
+```bash
+pixi run update-test-channel dummy_channel_1
+```
+After updating the test channel, run the tests again:
+```
+pixi run test
+```
+
 ## CLI documentation
 The CLI reference is automatically generated from the code documentation of CLI commands under `src/cli`.