[tests] add tests for the various Network constructors

tests/introspection/ApiCMAttachmentTest.cs

@@ -224,6 +224,11 @@ namespace Introspection {
 			case "ABMutableMultiValue":
 			case "SecProtocolMetadata": // Read-only object that is surfaced during TLS negotiation callbacks, can not be created from user code.
 			case "SecProtocolOptions":  // Read-only object that is surfaced during TLS negotiation callbacks, can not be created from user code.
+			case "NWError":               // Only ever surfaced, not created from usercode
+			case "NWInterface":           // Only ever surfaced, not created from usercode
+			case "NWPath":                // Only ever surfaced, not created from usercode
+			case "NWProtocolStack":       // Only ever surfaced, not created from usercode
+			case "NWProtocolMetadata":    // While technically it can be created and the header files claim the methods exists, the library is missing the methods (radar: 42443077)
 			case "ABSource": // not skipped when running on iOS 6.1
 			// type was removed in iOS 10 (and replaced) and never consumed by other API
 			case "CGColorConverter":
@@ -418,6 +423,26 @@ namespace Introspection {
 					new CVPixelBufferPoolSettings (),
 					new CVPixelBufferAttributes (CVPixelFormatType.CV24RGB, 100, 50)
 				);
+			case "NWAdvertiseDescriptor":
+				return new NWAdvertiseDescriptor ("sampleName" + DateTime.Now);
+			case "NWConnection": {
+				var endpoint = NWEndpoint.Create ("www.microsoft.com", "https");
+				var parameters = NWParameters.CreateTcp (configureTcp: null);
+				return new NWConnection (endpoint, parameters);
+			}
+			case "NWContentContext":
+				return new NWContentContext ("contentContext" + DateTime.Now);
+			case "NWEndpoint":
+				return NWEndpoint.Create ("www.microsoft.com", "https");
+			case "NWListener":
+				return NWListener.Create (NWParameters.CreateTcp (configureTcp: null));
+			case "NWParameters":
+				return NWParameters.CreateTcp (configureTcp: null);
+			case "NWProtocolDefinition":
+				// Makes a new instance every time
+				return NWProtocolDefinition.TcpDefinition;
+			case "NWProtocolOptions":
+				return NWProtocolOptions.CreateTcp ();
 			case "SecCertificate":
 				using (var cdata = NSData.FromArray (mail_google_com))
 					return new SecCertificate (cdata);