Make the commands tests robust against any working directory changes done by the tool being tested in the same process (as for example --package-path does). (#3868)

Author: abertelrud

Tests/CommandsTests/APIDiffTests.swift

@@ -18,7 +18,7 @@ import TSCBasic
 import Workspace
 import XCTest
 
-final class APIDiffTests: XCTestCase {
+final class APIDiffTests: CommandsTestCase {
     @discardableResult
     private func execute(
         _ args: [String],

Tests/CommandsTests/BuildToolTests.swift

@@ -25,7 +25,7 @@ struct BuildResult {
     let binContents: [String]
 }
 
-final class BuildToolTests: XCTestCase {
+final class BuildToolTests: CommandsTestCase {
     @discardableResult
     private func execute(
         _ args: [String],

Tests/CommandsTests/CommandsTestCase.swift

@@ -0,0 +1,30 @@
+/*
+ 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
+import XCTest
+
+class CommandsTestCase: XCTestCase {
+    
+    /// Original working directory before the test ran (if known).
+    private var originalWorkingDirectory: AbsolutePath? = .none
+    
+    override func setUp() {
+        originalWorkingDirectory = localFileSystem.currentWorkingDirectory
+    }
+    
+    override func tearDown() {
+        if let originalWorkingDirectory = originalWorkingDirectory {
+            try? localFileSystem.changeCurrentWorkingDirectory(to: originalWorkingDirectory)
+        }
+    }
+    
+    // FIXME: We should also hoist the `execute()` helper function that the various test suites implement, but right now they all seem to have slightly different implementations, so that's a later project.
+}

Tests/CommandsTests/MultiRootSupportTests.swift

@@ -15,7 +15,7 @@ import TSCBasic
 import Workspace
 import XCTest
 
-final class MultiRootSupportTests: XCTestCase {
+final class MultiRootSupportTests: CommandsTestCase {
 
     func testWorkspaceLoader() throws {
         let fs = InMemoryFileSystem(emptyFiles: [

Tests/CommandsTests/PackageRegistryToolTests.swift

@@ -19,7 +19,7 @@ import XCTest
 let defaultRegistryBaseURL = URL(string: "https://packages.example.com")!
 let customRegistryBaseURL = URL(string: "https://custom.packages.example.com")!
 
-final class PackageRegistryToolTests: XCTestCase {
+final class PackageRegistryToolTests: CommandsTestCase {
     @discardableResult
     private func execute(
         _ args: [String],

Tests/CommandsTests/PackageToolTests.swift

@@ -22,7 +22,7 @@ import Workspace
 import Xcodeproj
 import XCTest
 
-final class PackageToolTests: XCTestCase {
+final class PackageToolTests: CommandsTestCase {
     @discardableResult
     private func execute(
         _ args: [String],

Tests/CommandsTests/RunToolTests.swift

@@ -14,7 +14,8 @@ import SPMTestSupport
 import Commands
 import TSCBasic
 
-final class RunToolTests: XCTestCase {
+final class RunToolTests: CommandsTestCase {
+    
     private func execute(
         _ args: [String],
         packagePath: AbsolutePath? = nil

Tests/CommandsTests/SwiftToolTests.swift

@@ -14,7 +14,8 @@ import SPMTestSupport
 import TSCBasic
 import XCTest
 
-final class SwiftToolTests: XCTestCase {
+final class SwiftToolTests: CommandsTestCase {
+    
     func testVerbosityLogLevel() throws {
         fixture(name: "Miscellaneous/Simple") { packageRoot in
             do {

Tests/CommandsTests/TestToolTests.swift

@@ -13,7 +13,8 @@ import XCTest
 import SPMTestSupport
 import Commands
 
-final class TestToolTests: XCTestCase {
+final class TestToolTests: CommandsTestCase {
+    
     private func execute(_ args: [String]) throws -> (stdout: String, stderr: String) {
         return try SwiftPMProduct.SwiftTest.execute(args)
     }