how do i

usage

...limit the build to a certain composition?

The default value of the names option will cause all the compositions to be built, and only the root composition to be released. You need to give a custom value.

You will probably want to set it from an environment variable, so that certain npm scripts can build different compositions.

...stop tests being built by default?

The default behaviour is determined by the otherwise() statement. Refer to usage.

Simply remove test from otherwise().

extensibility