### Question:
ExpressionTokenizer { public ExpressionTokenType next() { if (type == EOE) { token = null; return EOE; } ExpressionTokenType currentType = type; prepareToken(); peek(); return currentType; } ExpressionTokenizer(String expression); ExpressionTokenType next(); String getToken(); int getPosition(); void setPosition(int position, boolean binaryOpAvailable);  }### Answer:
@Test public void testFieldOperator_identifierNotFound() { ExpressionTokenizer tokenizer = new ExpressionTokenizer("aaa."); try { tokenizer.next(); fail(); } catch (ExpressionException expected) { System.out.println(expected.getMessage()); assertEquals(Message.DOMA3021, expected.getMessageResource()); } }
@Test public void testFieldOperator_illegalJavaIdentifierStart() { ExpressionTokenizer tokenizer = new ExpressionTokenizer("aaa.!"); try { tokenizer.next(); fail(); } catch (ExpressionException expected) { System.out.println(expected.getMessage()); assertEquals(Message.DOMA3022, expected.getMessageResource()); } }