Test Apex Triggers Challenge

TestRestrictContactByName.apxc

@isTest
private class TestRestrictContactByName {

    @isTest static void testInvalidName() {
        //try inserting a Contact with INVALIDNAME
        Contact myConact = new Contact(LastName='INVALIDNAME');
        insert myConact;
        
        // Perform test
        Test.startTest();
        Database.SaveResult result = Database.insert(myConact, false);
        Test.stopTest();
        // Verify 
        // In this case the creation should have been stopped by the trigger,
        // so verify that we got back an error.
        System.assert(!result.isSuccess());
        System.assert(result.getErrors().size() > 0);
        System.assertEquals('Cannot create contact with invalid last name.',
                             result.getErrors()[0].getMessage());
        
    }
}

I know this is old but I am trying to learn this content and I'm confused---I passed the challenge but when I run the tests in the Developer Console the tests say that they fail:

System.DmlException: Insert failed. First exception on row 0; first error: FIELD_CUSTOM_VALIDATION_EXCEPTION, The Last Name "INVALIDNAME" is not allowed for DML: []

Obviously I was expecting the issue with the "INVALIDNAME" but I would expect that the test would succeed because I was testing for the failure. I am worried that if I were to try to deploy this code that I wouldn't be able to because the Apex tests would fail.

Thoughts? Thanks so much.

Have you put INVALIDNAME inside single quotes for validation?

if you do this:

Contact contact= new Contact(LastName='INVALIDNAME');

the code will compile
but if you do this instead:

Contact contact= new Contact(LastName=INVALIDNAME);

Salesforce will try to use the value of a custom field named INVALIDNAME in the object Contact, and won't compile.
This will be shown on the "Problems" tab on Developer Console

I know this is old but I am trying to learn this content and I'm confused---I passed the challenge but when I run the tests in the Developer Console the tests say that they fail:

System.DmlException: Insert failed. First exception on row 0; first error: FIELD_CUSTOM_VALIDATION_EXCEPTION, The Last Name "INVALIDNAME" is not allowed for DML: []

Obviously I was expecting the issue with the "INVALIDNAME" but I would expect that the test would succeed because I was testing for the failure. I am worried that if I were to try to deploy this code that I wouldn't be able to because the Apex tests would fail.

Thoughts? Thanks so much.

Remove line 7, "insert myConact;". That is causing the issue you are seeing with the test failing. The db insert between test.start/test.stop, will save the result and then the assertions will pass, and the test will run successfully.

Just reporting a silly mistake I made. Wanted to post this here in case anybody else makes the same mistake I did.
I was getting the error:

System.DmlException: Insert failed. First exception on row 0; first error: FIELD_CUSTOM_VALIDATION_EXCEPTION, The Last Name "INVALIDNAME" is not allowed for DML

and found that I was missing the false argument in the Database.insert() statement (line 11).