Generally speaking, running one test is the easiest from your IDE. Select one test method of JUnit or one test scenario of Cucumber, then ask the IDE to run it.
To run a single JUnit test from command line, specify the name of the test with the -Dtest= option:
mvn -Dtest=AntPluginTest#autoInstallAnt test
It need not specify a fully qualified class name. See Maven surefire plugin for more details about how to specify a group of tests.
To run a single Cucumber test from command line, specify a (relative) path to a feature file, optionally with a line number to specify a specific scenario
mvn -Dcucumber.test=features/freestyle_build.feature:6 test
TODO: use a driver directly to skip all Maven stuff