How to by pass a nuclear test ban

Take a nation that has signed the nuclear test ban treaty, but which wishes to develop new nuclear weapons. Hypothetically let call them the (US)A.
Take a nation which has not agreed to any convention on nuclear weapon, lets call them I(ndia).
Take an allied nation to A, lets call them (australi)A.

Allow nation A to supply nation I with with technology, which disagree with policy of nation A for all nations B to I and K to Z.

Allow nation I to complete test as required.
Collect data from Nation I
Condemn nation I for doing test, apply sanctions and demand the abolition of nations I´s program.