2
2
Given the following test, implement an addOne function in C# so it passes, without any modification to the test. TIP: Yes, it is possible.
[TestMethod]
public void TheChallenge()
{
int a = 1;
addOne(a);
Assert.IsTrue(a == 2);
}
EDIT: clarified the Assert to avoid confusion. The value of a should be 2; there's no trick there.
istepaniuk
Posted 2013-01-10T21:13:59.433
Reputation: 139
14
Ummm, simply provide an implementation of AssertTrue that doesn't throw anything?
void addOne(int a){}
void AssertTrue(bool b) { }
You never specified what testing framework is used here. It looks like MSTest, but I fired up a new test project and AssertTrue doesn't exist, so I took the liberty of implementing it myself.
This solution might be what you were fishing for:
void addOne(int x)
{
unsafe
{
int* i = &x;
i += 4;
*i += 1;
}
}
I feels pretty fragile, but it works on my box consistently. It probably depends heavily on the compiler, so hopefully it is reproducible elsewhere.
captncraig
Posted 2013-01-10T21:13:59.433
Reputation: 4 373
+1 for lateral thinking, but the question states "Implement an addOne function" I will clarify the Assert to make it pure mstest. – istepaniuk – 2013-01-11T09:08:35.010
do you mean
void addOne(ref int a){a++;}– shiona – 2013-01-10T21:18:48.510That wouldn't compile. The ref keyword is not in the test (you would need
addOne(ref a);). – istepaniuk – 2013-01-10T21:22:27.137Perhaps you could use reflection to somehow rewrite the IL for the test method to increment a after the return. That's all I can think of. – captncraig – 2013-01-10T22:11:40.050
4This isn't a very code golf friendly question. – MrZander – 2013-01-10T22:36:34.150
@istepaniuk oh, I've never actually written any C#, so I googled and tried to understand the syntax for pass by reference. MrZander: it isn't tagged code golf. It's awfully simple for puzzle though. – shiona – 2013-01-10T23:06:59.123
No need to rewrite IL on runtime. But it goes on those lines of nasty hack. TIP: unsafe code is allowed – istepaniuk – 2013-01-11T09:10:35.147
@MrZander, @shiona; please tag accordingly, I'm new here. – istepaniuk – 2013-01-11T11:35:04.097