Fixed TLS evaluation test that can fail in a different way when behind a proxy.

Tests/TLSEvaluationTests.swift

@@ -93,12 +93,15 @@ class TLSEvaluationExpiredLeafCertificateTestCase: BaseTestCase {
         waitForExpectations(timeout: timeout, handler: nil)
 
         // Then
-        XCTAssertNotNil(error, "error should not be nil")
+        XCTAssertNotNil(error)
 
         if let error = error as? URLError {
-            XCTAssertEqual(error.code, .serverCertificateUntrusted, "code should be untrusted server certficate")
+            XCTAssertEqual(error.code, .serverCertificateUntrusted)
+        } else if let error = error as? NSError {
+            XCTAssertEqual(error.domain, kCFErrorDomainCFNetwork as String)
+            XCTAssertEqual(error.code, Int(CFNetworkErrors.cfErrorHTTPSProxyConnectionFailure.rawValue))
         } else {
-            XCTFail("error should be a URLError")
+            XCTFail("error should be a URLError or NSError from CFNetwork")
         }
     }