Yes

yes ;)

ahaha wtf y "" != null?

thx i rly dont forgot about one :D, but can u explain to me, what the compiler wants to see from me :)
Test Failed
Expected: <string.Empty>
But was: null

Random Tests, System.NullReferenceException : Object reference not set to an instance of an object.

There is your answer. Sample tests are just that - examples. Many more tests when you hit 'attempt', usually random. It's hard to tell where the error comes from, but it's from your code. Start by reading THIS.

that's because the full test suite (using "attempt") contains more tests then the sample tests. You'll find some bit of information there.

=> first things first: print the inputs / try to get why your code fails on that input (edit: reading the error message is actually quite useful in this kind of situation... ;o )

wtf, y im send my code and if i click test then my code compiled and send me status true :sample test completed, but if i send finaly tests(attempt) then sample test not compilied and send me error NullReferences wtf guys
//click on button send
Test Results:
Solution
SolutionTest
SampleTest
Completed in 20.5900ms
Completed in 23.5130ms
You have passed all of the tests! :)
//click on button attempt
Test Results:
Solution
SolutionTest
Random Tests
SampleTest
System.NullReferenceException : Object reference not set to an instance of an object.
Stack Trace
at Kata.AlphabetPosition(String text)
at Solution.SolutionTest.SampleTest()
Completed in 16.0730ms
Completed in 58.1370ms
Completed in 60.9550ms