Merge pull request #71558 from nate-chandler/test/20240212/1/troubleshoot-test-note

[Test] Added troubleshooting note.

Author: nate-chandler

SwiftCompilerSources/Sources/Optimizer/Utilities/Test.swift

@@ -21,6 +21,23 @@
 //
 //===----------------------------------------------------------------------===//
 //
+// TO TROUBLESHOOT A NEW TEST, consider the following scenarios:
+// - PROBLEM: The test isn't running on PLATFORM and the failure says
+//
+//                Found no test named my_new_test.
+//
+//   SOLUTION: Is this a platform one that doesn't use SwiftCompilerSources
+//             (e.g. Windows)?  Then add
+//
+//                 // REQUIRES: swift_in_compiler
+//
+//             to the test file.
+//   EXPLANATION: The tests written within SwiftCompilerSources only get built
+//                and registered on platforms where the SwiftCompilerSources are
+//                built and used.
+//
+//===----------------------------------------------------------------------===//
+//
 // Provides a mechanism for writing tests against compiler code in the context
 // of a function.  The goal is to get the same effect as calling a function and
 // checking its output.