Update tests

src/test/java/seedu/address/logic/commands/EditAppointmentCommandTest.java

@@ -2,11 +2,13 @@
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 import static seedu.address.logic.commands.CommandTestUtil.VALID_DATE;
 import static seedu.address.logic.commands.CommandTestUtil.assertCommandFailure;
 import static seedu.address.logic.commands.CommandTestUtil.assertCommandSuccess;
 import static seedu.address.logic.commands.CommandTestUtil.showAppointmentAtIndex;
+import static seedu.address.testutil.TypicalAppointments.APPOINTMENT_1;
 import static seedu.address.testutil.TypicalAppointments.getTypicalAddressBook;
 import static seedu.address.testutil.TypicalIndexes.INDEX_FIRST_APPOINTMENT;
 import static seedu.address.testutil.TypicalIndexes.INDEX_SECOND_APPOINTMENT;
@@ -17,6 +19,7 @@
 import seedu.address.commons.core.index.Index;
 import seedu.address.logic.Messages;
 import seedu.address.logic.commands.EditAppointmentCommand.EditAppointmentDescriptor;
+import seedu.address.logic.commands.exceptions.CommandException;
 import seedu.address.model.AddressBook;
 import seedu.address.model.Model;
 import seedu.address.model.ModelManager;
@@ -103,6 +106,16 @@ public void execute_filteredList_success() {
         assertCommandSuccess(editAppointmentCommand, model, expectedMessage, expectedModel);
     }
 
+    @Test
+    public void execute_appointmentAlreadyExists_failure() {
+        model.addAppointment(APPOINTMENT_1);
+        Index idx = Index.fromOneBased(1);
+        EditAppointmentDescriptor descriptor = new EditAppointmentDescriptorBuilder().withDate("2124-03-19").build();
+        EditAppointmentCommand editAppointmentCommand = new EditAppointmentCommand(idx, descriptor);
+
+        assertThrows(CommandException.class, () -> editAppointmentCommand.execute(model));
+    }
+
     @Test
     public void execute_invalidAppointmentIndexUnfilteredList_failure() {
         Index outOfBoundIndex = Index.fromOneBased(model.getFilteredAppointmentList().size() + 1);