diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 0ac33346..c903a20b 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -29,6 +29,19 @@ only `TokamakStaticHTML`, single-page apps would use `TokamakDOM`, maybe in conj
 Android at some point, probably in a separate `TokamakAndroid` module, Android apps would use
 `TokamakAndroid` with no need to be aware of any of the web modules.
 
+### Testing
+
+Tokamak uses [SnapshotTesting](https://github.com/pointfreeco/swift-snapshot-testing) library to
+make sure that HTML and layout generated by renderers stay consistent. To run the test suite on macOS
+you should use this command:
+
+```sh
+swift build --product TokamakPackageTests && `xcrun --find xctest` .build/debug/TokamakPackageTests.xctest
+```
+
+Unfortunately, plain `swift test` won't work as it tries to build targets that aren't related to
+the test suite.
+
 ### Coding Style
 
 This project uses [SwiftFormat](https://github.com/nicklockwood/SwiftFormat) and