Checks (or selects) this fixture's {@link JRadioButton} only it is not already checked.
@return this fixture.
@throws IllegalStateException if this fixture's JRadioButton is disabled.
@throws IllegalStateException if this fixture's JRadioButton is not showing on the screen.
All source code are property of their respective owners. Java is a trademark of Sun Microsystems, Inc and owned by ORACLE Inc. Contact coftware#gmail.com.