from 101regexp:

in style guide there is , a following colon , any ideas on how to make it ?

@mohitsatr Please use following config:

<module name="TodoComment">
      <property name="format" value="^[ \t]*(?!TODO:)(?i:TODO)\b:?"/>
      <message key="todo.match" value="Todo comments must use ''TODO:'' in all caps."/>
 </module>

This regex gives violation only when the "todo" is present at the beginning. Also it ensures that : is present after TODO. I have also modified the violation message a bit and used 'TODO:'

@romani fyi

The above mentioned regex doesn't violates when there's no whitespace after :, for example:

  void myFunc16(int i) {
    // TODO:implementing
  }

this case passes. Style guide doesn't mention anything about enforcing a whitespace after : so I think this should be okay.

^^^ this should be no violation.
@mohitsatr , please extend test cases

done

resolved.

Please also add these examples:

  void myFunc32(int i) {
    // tODo implementing
    // violation above 'Todo comments must use 'TODO:' in all caps'
  }

  void myFunc33(int i) {
    // TODO implementing
    // violation above 'Todo comments must use 'TODO:' in all caps'
  }

  void myFunc34(int i) {
    // TODO: correct TODO comment
  }

  void myFunc35(int i) {
    // TODO:correct TODO comment
  }

done

resolved.