* @throws PsInterpreterException4a For PostScript errors.
* @throws PsOperatorException For PostScript operator errors.
*/
private void generalBooleanTest(final String testString, final boolean expectedResult)
throws PsInterpreterException4a, PsOperatorException {
final PsInput input = new PsStringInput(testString);
final PsInterpreter4a interpreter = new PsInterpreter4a(input, null);
interpreter.process();
final PsObject object = interpreter.getOperandStack().pop();
assertTrue(object instanceof PsBoolean);
assertEquals(expectedResult, ((PsBoolean) object).getValue());