Implement a round-trip integration test

To exercise the full message sending/receiving path.

Tests/SecureXPCTests/Client & Server/Round-trip Integration Test.swift

@@ -0,0 +1,93 @@
+//
+//  Round-trip Integration Test.swift
+//  
+//
+//  Created by Alexander Momchilov on 2021-11-28.
+//
+
+import XCTest
+@testable import SecureXPC
+
+class RoundTripIntegrationTest: XCTestCase {
+    var xpcClient: XPCClient! = nil
+
+    let anonymousServer = XPCServer.makeAnonymousService()
+
+    override func setUp() {
+        let endpoint = anonymousServer.endpoint
+        xpcClient = XPCClient.forEndpoint(endpoint)
+
+        anonymousServer.start()
+    }
+
+    func testSendWithMessageWithReply() throws {
+        let remoteHandlerWasCalled = self.expectation(description: "The remote handler was called")
+        let replyBlockWasCalled = self.expectation(description: "The echo reply was received")
+
+        let echoRoute = XPCRouteWithMessageWithReply("echo", messageType: String.self, replyType: String.self)
+        try anonymousServer.registerRoute(echoRoute) { msg in
+            remoteHandlerWasCalled.fulfill()
+            return "echo: \(msg)"
+        }
+
+        try self.xpcClient.sendMessage("Hello, world!", route: echoRoute) { result in
+            XCTAssertNoThrow {
+                let response = try result.get()
+                XCTAssertEqual(response, "echo: Hello, world!")
+            }
+
+            replyBlockWasCalled.fulfill()
+        }
+
+        self.waitForExpectations(timeout: 1)
+    }
+
+    func testSendWithoutMessageWithReply() throws {
+        let remoteHandlerWasCalled = self.expectation(description: "The remote handler was called")
+        let replyBlockWasCalled = self.expectation(description: "The pong reply was received")
+
+        let pingRoute = XPCRouteWithoutMessageWithReply("ping", replyType: String.self)
+        try anonymousServer.registerRoute(pingRoute) {
+            remoteHandlerWasCalled.fulfill()
+            return "pong"
+        }
+
+        try self.xpcClient.send(route: pingRoute) { result in
+            XCTAssertNoThrow {
+                let response = try result.get()
+                XCTAssertEqual(response, "pong")
+            }
+
+            replyBlockWasCalled.fulfill()
+        }
+
+        self.waitForExpectations(timeout: 1)
+    }
+
+    func testSendWithMessageWithoutReply() throws {
+        let remoteHandlerWasCalled = self.expectation(description: "The remote handler was called")
+
+        let msgNoReplyRoute = XPCRouteWithMessageWithoutReply("msgNoReplyRoute", messageType: String.self)
+        try anonymousServer.registerRoute(msgNoReplyRoute) { msg in
+            XCTAssertEqual(msg, "Hello, world!")
+            remoteHandlerWasCalled.fulfill()
+        }
+
+        try self.xpcClient.sendMessage("Hello, world!", route: msgNoReplyRoute)
+
+        self.waitForExpectations(timeout: 1)
+    }
+
+    func testSendWithoutMessageWithoutReply() throws {
+        let remoteHandlerWasCalled = self.expectation(description: "The remote handler was called")
+
+        let noMsgNoReplyRoute = XPCRouteWithoutMessageWithoutReply("noMsgNoReplyRoute")
+        try anonymousServer.registerRoute(noMsgNoReplyRoute) {
+            remoteHandlerWasCalled.fulfill()
+        }
+
+        try self.xpcClient.send(route: noMsgNoReplyRoute)
+
+        self.waitForExpectations(timeout: 1)
+    }
+}