Write tests for sum operation

[GabrieleMessina]

Here something to check

qubit a = [true]q;
qubit b = [true]q;
int classical = a + 1;

qubit a = [true]q;
qubit b = [true]q;
qubit c = [true]q;
qubit d = a + b + c;

int a = 12;
qubit b = [true]q;
// 'a' should be casted to quint.
//We can measure 'b' and then sum classically to 'a' but that would not be a smart choice because 'c' cannot take advantage from the quantum state of 'b' 
quint c = a + b;