Use the correct test method

Author: natecook1000

test/stdlib/Filter.swift

@@ -79,15 +79,15 @@ FilterTests.test("chained filter order") {
   let lazyFilter = array.lazy
     .filter { _ in false }
     .filter { _ in
-      expectationFailure("Executed second filter before first")
+      expectUnreachable("Executed second filter before first")
       return true
     }
   let lazyResult = Array(lazyFilter)
 
   let result = array
     .filter { _ in false }
     .filter { _ in
-      expectationFailure("Executed second filter before first")
+      expectUnreachable("Executed second filter before first")
       return true
     }