We had bug report that an error during TLS handshake does not get correctly reported and instead a deadlineExceeded error is thrown. We have already fixed the issue in #588 and this PR just adds a test to verify the behavior.

Modifications:

• add test testSelfSignedCertificateIsRejectedWithCorrectError which uses a self signed certificate to fail the TLS handshake
• improve error description of NWTLSError. Previously a TLS error had a description that looked like this:

The operation couldn’t be completed. (Network.NWError error 2.)

which contains not enough for further investigation. It now contains the OSStatus code too which can be used to find out what actually went wrong:

-9808: Optional(bad certificate format)

• make internal class NWErrorHandler final
• fix error message of XCTAssertEqualTypeAndValue. It had the left hand side type and right hand side swapped.

Result

Improved test coverage and better error messages