### Question:
MinValidatorForString implements ConstraintValidator<Min, String> { public boolean isValid(String value, ConstraintValidatorContext constraintValidatorContext) { if ( value == null ) { return true; } try { return new BigDecimal( ( String ) value ).compareTo( BigDecimal.valueOf( minValue ) ) != -1; } catch ( NumberFormatException nfe ) { return false; } }  void initialize(Min minValue); boolean isValid(String value, ConstraintValidatorContext constraintValidatorContext);  }### Answer:
@Test public void testIsValid() { assertTrue( constraint.isValid( null, null ) ); assertTrue( constraint.isValid( "20", null ) ); assertTrue( constraint.isValid( "15", null ) ); assertTrue( constraint.isValid( "15.0", null ) ); assertFalse( constraint.isValid( "10", null ) ); assertFalse( constraint.isValid( "14.99", null ) ); assertFalse( constraint.isValid( "-14.99", null ) ); assertFalse( constraint.isValid( "15l", null ) ); }