Ternary statement mutations

At the moment, mutations are being placed inside if statements like this

if(Environment.GetEnvironmentVariable("ActiveMutation") == "<id>") {
    // mutation
} else {
    // original
}

Not all mutations can be inserted like this. Some mutations can only be inserted using ternary statements like this:

var localVariable = if(Environment.GetEnvironmentVariable("ActiveMutation") == "<id>") ? // mutation : //original

These kind of mutations should also be rollbacked different. My suggestion is an interface for both type of mutant placements. Something like:

public interface IMutantPlacement {
    SyntaxNode InsertMutant(SyntaxNode, Mutant);
    SyntaxNode RemoveMutant(SyntaxNode, Mutant);
}

It would have two implementations. One for if statements and one for ternary mutations.

[kevinlyles]

Alright, I think I have things working. We end up using ternary mutations for expressions and if mutations only for statements, which means a lot more ternary mutations but often a lot less code overall.

I have a proof of concept (with some new tests and all tests passing) at https://github.com/kevinlyles/stryker-net/tree/issue-17, but I probably won’t have time to clean things up until next week. Feel free to have a look, and let me know what you think.

[richardwerkman]

Well the type LocalFunctionStatement can contain a Body,

int Add(int x, int y) {
    return x + y;
}

or an ExpressionBody

int Add(int x, int y) => x + y;

One should be mutated by IfStatements, the other by ConditionalExpression. But I think I have figured out a way to nicely handle this.