Added missing test cases for submissions.py

[jayaike]

Added missing Test Cases for submissions.py

@lunayach , @Ram81 , @RishabhJain2018 , @vkartik97 ,I have added the missing test cases to the file indicated in the task. However, despite it getting 100% code coverage, the overall code coverage is 89%. I guess that might be a miscalculation.

The second thing is in order to add the test case for the missing schema. I had to move the code that catches the exception to the function where it is supposed to be as it was not getting called in its former position due to the fact that it was in the wrong function. I have fixed that now.

The new code I have provided has 100% coverage in the submissions test as I have written the remaining test cases. The code does not break.

Please let me know if you have any comments. Thank you

[pushkalkatara]

Nice work @nsjcorps, Looks good to me too.