Add a test for WorkspaceState serialization stability (#3788)

Author: Randy Becker

Tests/WorkspaceTests/WorkspaceStateTests.swift

@@ -0,0 +1,80 @@
+/*
+ This source file is part of the Swift.org open source project
+
+ Copyright (c) 2021 Apple Inc. and the Swift project authors
+ Licensed under Apache License v2.0 with Runtime Library Exception
+
+ See http://swift.org/LICENSE.txt for license information
+ See http://swift.org/CONTRIBUTORS.txt for Swift project authors
+ */
+
+import TSCBasic
+@testable import Workspace
+import XCTest
+
+final class WorkspaceStateTests: XCTestCase {
+    func testSavedDependenciesAreSorted() throws {
+        let fs = InMemoryFileSystem()
+
+        let buildDir = AbsolutePath("/.build")
+        let statePath = buildDir.appending(component: "workspace-state.json")
+
+        try fs.writeFileContents(statePath) {
+            $0 <<<
+                """
+                {
+                    "object": {
+                        "artifacts": [],
+                        "dependencies": [
+                            {
+                                "basedOn": null,
+                                "packageRef": {
+                                  "identity": "yams",
+                                  "kind": "remoteSourceControl",
+                                  "location": "https://github.com/jpsim/Yams.git",
+                                  "name": "Yams"
+                                },
+                                "state": {
+                                  "checkoutState": {
+                                    "revision": "9ff1cc9327586db4e0c8f46f064b6a82ec1566fa",
+                                    "version": "4.0.6"
+                                  },
+                                  "name": "checkout"
+                                },
+                                "subpath": "Yams"
+                            },
+                            {
+                                "basedOn": null,
+                                "packageRef": {
+                                  "identity": "swift-argument-parser",
+                                  "kind": "remoteSourceControl",
+                                  "location": "https://github.com/apple/swift-argument-parser.git",
+                                  "name": "swift-argument-parser"
+                                },
+                                "state": {
+                                  "checkoutState": {
+                                    "revision": "83b23d940471b313427da226196661856f6ba3e0",
+                                    "version": "0.4.4"
+                                  },
+                                  "name": "checkout"
+                                },
+                                "subpath": "swift-argument-parser"
+                            }
+                        ]
+                    },
+                    "version": 4
+                }
+                """
+        }
+
+        let state = WorkspaceState(dataPath: buildDir, fileSystem: fs)
+        try state.save()
+
+        let serialized = try fs.readFileContents(statePath).description
+
+        let argpRange = try XCTUnwrap(serialized.range(of: "swift-argument-parser"))
+        let yamsRange = try XCTUnwrap(serialized.range(of: "yams"))
+
+        XCTAssertTrue(argpRange.lowerBound < yamsRange.lowerBound)
+    }
+}