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test/README.md

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+Testing
+=======
+
+The tests are organized by testing language. Thus Pester tests, which
+are written in the PowerShell language, are in
+[./powershell](./powershell) and xUnit tests, written in C#, are in
+[./csharp](./csharp). The sanity tests for the Full .NET build of
+PowerShell are in [./fullclr](./fullclr), and the third-party
+[shebang][] test is in [./shebang](./shebang).
+
+[shebang]: https://en.wikipedia.org/wiki/Shebang_(Unix)