Changed Target Tasks Plugin

A plugin for the pants build system make building and testing locally edited (or a particular commit's) targets easier.

Details

This creates varients of goals like compile that, rather than operate on explicitly provided arguments, find "changed" targets by consulting the active SCM (eg git) and then operate on those and (optionally) on their dependees.

Provided goals are:

• what-changed: Lists changed targets (or writes to file)
• compile-changed: Build changed targets
• test-changed: Test changed targets
• validate-changed: Check for dependency rules in changed targets

All of thse take flags which can change how they find targets and whether or not they include dependees.

Determining what is "changed"

"changed" is usually determined asking SCM for files with differences relative to "upstream/master", though this is configurable via the --changes-since flag or config option.

"changed" can also be determined by --diffspec (or --shas). A diffspec can be a single SHA, a aaa..bbb range, a ref or anything that is meaningful to the SCM to provide a list of changed filenames.

Including Dependees

These tasks are useful for checking if ones current changes break things, without having to know what "things" may have been broken and need to be built (or tested) to be sure.

However, most changes can not only break the targets in which they are made, but can easily break a dependee, eg by changing a method which is called in a dependee. Thus including depnedees of changed targets in addition to changed targets themselves is often helpful.

• --direct-dependees or --dd

Include direct dependees of changed targets. (This is the default behavior, but can be explicitly chosen if defaults are changed via config.)

• --transitive-dependees or --td

Include all transitive dependees.

• --no-dependees or --nd

Include no dependees, and act only on directly changed targets.