SAT: check oneOf common property has only const keyword, no default and enum keywords

[grubberr]

We need to improve SAT test_oneof_usage to check that common oneOf property looks like this:

"option_title": {
    "type": "string",
    "const": "OAuth Credentials",
    "order": 0
}

only const keyword
NO MORE default and enum keywords.

old value

"option_title": {
    "type": "string",
    "const": "OAuth Credentials",
    "enum": ["OAuth Credentials"],
    "default": "OAuth Credentials",
    "order": 0
}

[sherifnada]

@grubberr cant we just use const keyword always instead of adding the enum and default keywords?

[grubberr]

@sherifnada I just checked, const only keyword also can work!

I see we have 2 option:

1. add new SAT test which makes sure we have only const and don't have enum and don't have default keywords

or

2. also check (1) but to be backward compatible if not (1) also check if we have all 3 keywords check that const == default and const in enum

What is better (a) or (b) ? What do you think ?

[sherifnada]

I think 1 is better, because it makes the iface simpler for the user