New Rule: UnnecessaryRequireNotNull

[pbreault]

Expected Behavior of the rule

Would there be any appetite for a new UnnecessaryRequireNotNull rule?

This would be similar to UnnecessaryNotNullOperator but it would flag calls to requireNotNull with a non-nullable parameter.

// non compliant code 
var string = "foo"
println(requireNotNull(string))

// compliant code
var string : String? = "foo"
println(requireNotNull(string))

Context

We have seen optional field become required after refactorings, leaving behind unnecessary calls to requireNotNull.
We have built a custom rule to detect these cases and we would like to contribute it back.

[3flex]

I think this would be a great addition, and should also check for the same case with checkNotNull. We'd need a different rule name if it checks both cases though (or a separate rule for check, but I don't think that makes sense).

[schalkms]

I second this. This rule would be a great addition to detekt.
Shall the rule be called UnnecessaryNotNullCheck?

@pbreault may I ask you to take a stab at this rule?

[pbreault]

I think a single UnnecessaryNotNullCheck rule that encompasses checkNotNull and requireNotNull makes sense. Definitely more future-proof. I'll take a stab at it.

[pbreault]

My colleague @VirtualParticle just opened #5218