Test Cases For defined "data type"

write test cases to test a new defined "data type" designed as required for a client? -
asked in a interview, company - "Oracle".

In general, a defined new data type in any language or any package

1 First we have to check the new defined data type is available in that particular
environment or not

2 whether the new defined data type is supported that particular environment or not.

3 whether the new defined data type is accepted specified Data or not.

4 Lower bound for that datatype (as each datatype has some lower limit), also check lower
limit -1

5 Upper bound for that datatype (as each datatype has some upper limit too), also check lower limit +1

6 also check any intermediate value too.All this is valid for scalar data types.