add validation to prevent self-referrals

[JamesChevalier]

Pull Request

Summary:

Adds a validation on Referral which blocks self-referrals

Related Issue:

Discussion #46

Description:

This fixes the existing situation which allows self-referrals:

user = User.first
referral_code = user.referral_codes.create
Refer.refer(code: referral_code.code, referee: user)

Testing:

Added test to ensure that the count of Referrals does not increase if both the referrer and referee are the same.

Screenshots (if applicable):

Checklist:

• Code follows the project's coding standards
• Tests have been added or updated to cover the changes
• Documentation has been updated (if applicable)
• All existing tests pass
• Conforms to the contributing guidelines

Additional Notes:

[excid3]

This is great, thanks @JamesChevalier! 🎉

[excid3]

Released in 1.0.2