Add information about `jsvu` and how to install it on mac.
# Running tests
+## Installation of JavaScript engines
+
+The latest engines can be installed with jsvu (JavaScript engine Version Updater https://github.com/GoogleChromeLabs/jsvu)
+
+* Install npm with brew:
+
+`brew install npm`
+
+* Install jsvu with npm:
+
+`npm install jsvu -g`
+
+* Run jsvu:
+
+`jsvu`
+
+Add `~/.jsvu` to your `PATH`:
+
+`export PATH="${HOME}/.jsvu:${PATH}"`
+
## Libraries tests
Library tests can be run with js engines: `v8`, `SpiderMonkey`,or `JavaScriptCore`: