If you plan to have documentation generation use -Ddisable-valadocs=false as an option to meson command.
For GObject Introspection use -Ddisable-introspection=false
GVls has unit test enable by default. To enable GUI tests, you should use -Dui-test-interactive=false -Dsubproject-gtktester=true -Ddisable-ui-tests=false, that will build GtkTester as subproject and will run all GUI tests without stop until finish. If you want to interact with the GUI Tets, you should use -Dui-test-interactive=true.