Cannot intercept construction

Author: David Ungar

Tests/SwiftDriverTests/IncrementalCompilationTests.swift

@@ -289,7 +289,7 @@ final class NonincrementalCompilationTests: XCTestCase {
 
 final class IncrementalCompilationTests: XCTestCase {
 
-  let tempDir: AbsolutePath
+  var tempDir: AbsolutePath = AbsolutePath("/tmp")
 
   let module = "theModule"
   var OFM: AbsolutePath {
@@ -336,19 +336,17 @@ final class IncrementalCompilationTests: XCTestCase {
     ]
     + inputPathsAndContents.map {$0.0.pathString} .sorted()
   }
-
-  override init(selector: Selector) {
-    // Prefix directory with test name to ensure directory name is unique when
-    // testing in parallel.
-    self.tempDir = try! withTemporaryDirectory(prefix: selector.description,  removeTreeOnDeinit: false) {$0}
-    super.init(selector: selector)
-  }
-
   deinit {
     try? localFileSystem.removeFileTree(tempDir)
   }
 
   override func setUp() {
+    // Prefix directory with test name to ensure directory name is unique when
+    // testing in parallel.
+    // name returns e.g. "[SwiftDriverTests.IncrementalCompilationTests testIncremental]
+    // but we just want "testIncremental"
+    let testName = name.split(separator: " ").last!.dropLast()
+    self.tempDir = try! withTemporaryDirectory(prefix: String(testName),  removeTreeOnDeinit: false) {$0}
     try! localFileSystem.createDirectory(derivedDataPath)
     writeOutputFileMapData(module: module,
                            inputPaths: inputPathsAndContents.map {$0.0},