customerFilterField.setText("a");
customerFilterField.postActionEvent();
assertEquals(Arrays.asList(new Customer[] {james, holger, kevin}), filteredCustomers);
customerFilterField.setText("a -B");
customerFilterField.postActionEvent();
assertEquals(Arrays.asList(new Customer[] {james}), filteredCustomers);
customerFilterField.setText("-B");
customerFilterField.postActionEvent();
assertEquals(Arrays.asList(new Customer[] {jesse, james}), filteredCustomers);