       let (swift: swift, swiftc: swiftc) =
           try makeDriverSymlinks(in: tempDir, with: swiftBuildDir)
 
-      var env = ProcessEnv.vars
-      env["SWIFT"] = swift.pathString
-      env["SWIFTC"] = swiftc.pathString
-      env["SWIFT_DRIVER_SWIFT_EXEC"] = frontendFile.pathString
-      
-      let process = TSCBasic.Process(args:
-        litFile.pathString, "-svi", "--time-tests", "--param",
-        "swift_site_config=\(litConfigFile.pathString)", testDir.pathString,
-        environment: env, outputRedirection: .none
+      let args = [
+        litFile.pathString, "-svi", "--time-tests",
+        "--param", "swift_site_config=\(litConfigFile.pathString)",
+        testDir.pathString
+      ]
+      
+      let extraEnv = [
+        "SWIFT": swift.pathString,
+        "SWIFTC": swiftc.pathString,
+        "SWIFT_DRIVER_SWIFT_EXEC": frontendFile.pathString
+      ]
+      
+      printCommand(args: args, extraEnv: extraEnv)
+      
+      let process = TSCBasic.Process(
+        arguments: args,
+        environment: ProcessEnv.vars.merging(extraEnv) { $1 },
+        outputRedirection: .none
       )
       try process.launch()
       let result = try process.waitUntilExit()


  return (swift: swift, swiftc: swiftc)
}
#endif



    try withTemporaryDirectory() { path in
      let (swift: _, swiftc: compiler) = try makeDriverSymlinks(in: path)

      let buildPath = path.appending(component: "build")
      let args = [
        "swift", "build", "--package-path", packageDirectory.pathString,
        "--build-path", buildPath.pathString
      ]
      let extraEnv = [ "SWIFT_EXEC": compiler.pathString]

      printCommand(args: args, extraEnv: extraEnv)

      let result = try TSCBasic.Process.checkNonZeroExit(
        arguments: args,
        environment: ProcessEnv.vars.merging(extraEnv) { $1 }
      )

      XCTAssertTrue(localFileSystem.isExecutableFile(buildPath.appending(RelativePath("debug/swift-driver"))), result)
