### Question:
ClientNot extends ClientOperator<ClientNot> { @Override public String toString() { String operand = (getOperand() != null) ? getOperand().toString() : ClientExpressions.MISSING_REPRESENTATION; if(getOperand() instanceof ClientOperator) { return getOperator().getDomelOperator() + " (" + operand + ")"; } return "("+ getOperator().getDomelOperator() +" "+ operand + ")"; } ClientNot();  ClientNot(ClientNot source);  ClientNot(ClientExpression expression, Boolean paren);  ClientNot(ClientOperation operation, List<ClientExpression> operands);  ClientNot(ClientExpression expression); @Override ClientNot addOperand(ClientExpression operand); static ClientNot not(ClientExpression expression); @XmlTransient ClientExpression getOperand(); @Override @Size(min = 1, max = 1, message = DOMEL_INCORRECT_OPERANDS_COUNT) List<ClientExpression> getOperands(); @Override String toString(); @Override void accept(ClientELVisitor visitor); ClientNot setParen(Boolean paren); @Override ClientNot setParen(); @Override ClientNot unsetParen(); @Override ClientNot deepClone(); @Override int getPrecedence(); static final String EXPRESSION_ID; }### Answer:
@Test public void toString_WithoutOperands() { ClientOperator instance = new ClientNot(); assertEquals("(not " + ClientExpressions.MISSING_REPRESENTATION + ")", instance.toString()); }
@Test public void toString_WithSomeSingleOperand() { ClientOperator instance = new ClientNot(TEST_CLIENT_EXPRESSION); assertEquals("(not " + TEST_INTEGER_VALUE + ")", instance.toString()); }