Restrict Switch Platform to macOS and Swift 6.1

Currently this command only supports Darwin SDKs on macOS, and code
editing support from Swift 6.1 and above. Only show the command for
these cases.

Also add a unit test for the command.

Issue: #1335

Author: rbenegal

README.md

@@ -46,7 +46,7 @@ The extension adds the following commands, available via the command palette.
 
 The following command is only available on macOS:
 
-- **Select Target Platform**: This is an experimental command that offers code completion for iOS and tvOS projects.
+- **Select Target Platform**: This is an experimental command that offers code editing support for iOS, tvOS, watchOS and visionOS projects.
 
 #### Building and Debugging
 

package.json

@@ -884,7 +884,7 @@
         },
         {
           "command": "swift.switchPlatform",
-          "when": "swift.isActivated && isMac"
+          "when": "swift.isActivated && isMac && swift.switchPlatformAvailable"
         },
         {
           "command": "swift.insertFunctionComment",

src/commands.ts

@@ -124,7 +124,9 @@ export function register(ctx: WorkspaceContext): vscode.Disposable[] {
                 return runTestMultipleTimes(ctx.currentFolder, item, true);
             }
         }),
-        // Note: This is only available on macOS (gated in `package.json`) because its the only OS that has the iOS SDK available.
+        // Note: switchPlatform is only available on macOS and Swift 6.1 or later
+        // (gated in `package.json`) because it's the only OS and toolchain combination that
+        // has Darwin SDKs available and supports code editing with SourceKit-LSP
         vscode.commands.registerCommand("swift.switchPlatform", () => switchPlatform(ctx)),
         vscode.commands.registerCommand(Commands.RESET_PACKAGE, () => resetPackage(ctx)),
         vscode.commands.registerCommand("swift.runScript", () => runSwiftScript(ctx)),

src/commands/switchPlatform.ts

@@ -19,7 +19,6 @@ import {
     getDarwinTargetTriple,
 } from "../toolchain/toolchain";
 import configuration from "../configuration";
-import { Version } from "../utilities/version";
 import { WorkspaceContext } from "../WorkspaceContext";
 
 /**
@@ -39,12 +38,7 @@ export async function switchPlatform(ctx: WorkspaceContext) {
         }
     );
     if (picked) {
-        if (ctx.toolchain.swiftVersion.isLessThan(new Version(6, 1, 0))) {
-            vscode.window.showWarningMessage(
-                "Code editing support for non-macOS platforms is only available starting Swift 6.1"
-            );
-        }
-        // show a status item as getSDKForTarget can sometimes take a long while to xcrun for the SDK
+        // show a status item as getSDKForTarget can sometimes take a long while to run xcrun to find the SDK
         const statusItemText = `Setting target platform to ${picked.label}`;
         ctx.statusItem.start(statusItemText);
         try {
@@ -60,8 +54,8 @@ export async function switchPlatform(ctx: WorkspaceContext) {
                     `Selecting the ${picked.label} target platform will provide code editing support, but compiling with a ${picked.label} SDK will have undefined results.`
                 );
             } else {
-                // set swiftSDK to undefined for macOS and other platforms
-                configuration.swiftSDK = undefined;
+                // set swiftSDK to an empty string for macOS and other platforms
+                configuration.swiftSDK = "";
             }
         } catch {
             vscode.window.showErrorMessage(

src/contextKeys.ts

@@ -77,6 +77,11 @@ interface ContextKeys {
      * Whether the SourceKit-LSP server supports documentation live preview.
      */
     supportsDocumentationLivePreview: boolean;
+
+    /**
+     * Whether the swift.switchPlatform command is available.
+     */
+    switchPlatformAvailable: boolean;
 }
 
 /** Creates the getters and setters for the VS Code Swift extension's context keys. */
@@ -92,6 +97,7 @@ function createContextKeys(): ContextKeys {
     let createNewProjectAvailable: boolean = false;
     let supportsReindexing: boolean = false;
     let supportsDocumentationLivePreview: boolean = false;
+    let switchPlatformAvailable: boolean = false;
 
     return {
         get isActivated() {
@@ -200,6 +206,15 @@ function createContextKeys(): ContextKeys {
                 value
             );
         },
+
+        get switchPlatformAvailable() {
+            return switchPlatformAvailable;
+        },
+
+        set switchPlatformAvailable(value: boolean) {
+            switchPlatformAvailable = value;
+            vscode.commands.executeCommand("setContext", "swift.switchPlatformAvailable", value);
+        },
     };
 }
 

src/extension.ts

@@ -76,12 +76,16 @@ export async function activate(context: vscode.ExtensionContext): Promise<Api> {
                 contextKeys.createNewProjectAvailable = toolchain.swiftVersion.isGreaterThanOrEqual(
                     new Version(5, 8, 0)
                 );
+                contextKeys.switchPlatformAvailable = toolchain.swiftVersion.isGreaterThanOrEqual(
+                    new Version(6, 1, 0)
+                );
                 return toolchain;
             })
             .catch(error => {
                 outputChannel.log("Failed to discover Swift toolchain");
                 outputChannel.log(error);
                 contextKeys.createNewProjectAvailable = false;
+                contextKeys.switchPlatformAvailable = false;
                 return undefined;
             });
 

test/unit-tests/commands/switchPlatform.test.ts

@@ -0,0 +1,85 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the VS Code Swift open source project
+//
+// Copyright (c) 2021-2025 the VS Code Swift project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of VS Code Swift project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+import { expect } from "chai";
+import * as vscode from "vscode";
+import {
+    mockObject,
+    mockGlobalObject,
+    mockGlobalModule,
+    MockedObject,
+    mockFn,
+    instance,
+} from "../../MockUtils";
+import {
+    DarwinCompatibleTarget,
+    SwiftToolchain,
+    getDarwinTargetTriple,
+} from "../../../src/toolchain/toolchain";
+import { WorkspaceContext } from "../../../src/WorkspaceContext";
+import { switchPlatform } from "../../../src/commands/switchPlatform";
+import { StatusItem } from "../../../src/ui/StatusItem";
+import configuration from "../../../src/configuration";
+
+suite("Switch Target Platform Unit Tests", () => {
+    const mockedConfiguration = mockGlobalModule(configuration);
+    const windowMock = mockGlobalObject(vscode, "window");
+    const mockSwiftToolchain = mockGlobalModule(SwiftToolchain);
+    let mockContext: MockedObject<WorkspaceContext>;
+    let mockedStatusItem: MockedObject<StatusItem>;
+
+    setup(() => {
+        mockedStatusItem = mockObject<StatusItem>({
+            start: mockFn(),
+            end: mockFn(),
+        });
+        mockContext = mockObject<WorkspaceContext>({
+            statusItem: instance(mockedStatusItem),
+        });
+    });
+
+    test("Call Switch Platform and switch to iOS", async () => {
+        const selectedItem = { value: DarwinCompatibleTarget.iOS, label: "iOS" };
+        windowMock.showQuickPick.resolves(selectedItem);
+        mockSwiftToolchain.getSDKForTarget.resolves("");
+        expect(mockedConfiguration.swiftSDK).to.equal("");
+
+        await switchPlatform(instance(mockContext));
+
+        expect(windowMock.showQuickPick).to.have.been.calledOnce;
+        expect(windowMock.showWarningMessage).to.have.been.calledOnceWithExactly(
+            "Selecting the iOS target platform will provide code editing support, but compiling with a iOS SDK will have undefined results."
+        );
+        expect(mockedStatusItem.start).to.have.been.called;
+        expect(mockedStatusItem.end).to.have.been.called;
+        expect(mockedConfiguration.swiftSDK).to.equal(
+            getDarwinTargetTriple(DarwinCompatibleTarget.iOS)
+        );
+    });
+
+    test("Call Switch Platform and switch to macOS", async () => {
+        const selectedItem = { value: undefined, label: "macOS" };
+        windowMock.showQuickPick.resolves(selectedItem);
+        mockSwiftToolchain.getSDKForTarget.resolves("");
+        expect(mockedConfiguration.swiftSDK).to.equal("");
+
+        await switchPlatform(instance(mockContext));
+
+        expect(windowMock.showQuickPick).to.have.been.calledOnce;
+        expect(windowMock.showWarningMessage).to.not.have.been.called;
+        expect(mockedStatusItem.start).to.have.been.called;
+        expect(mockedStatusItem.end).to.have.been.called;
+        expect(mockedConfiguration.swiftSDK).to.equal("");
+    });
+});