Only enable testing requiring @testable import if it’s actually available.

Additionally: allow building in Release correctly during development on Darwin.

Author: millenomi

Foundation.xcodeproj/project.pbxproj

@@ -2207,7 +2207,7 @@
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 			shellPath = /bin/sh;
-			shellScript = "cp ${BUILD_ROOT}/Debug/xdgTestHelper.app/Contents/MacOS/xdgTestHelper ${BUILD_ROOT}/Debug/TestFoundation.app/Contents/MacOS/";
+			shellScript = "cp ${BUILT_PRODUCTS_DIR}/xdgTestHelper.app/Contents/MacOS/xdgTestHelper ${BUILT_PRODUCTS_DIR}/TestFoundation.app/Contents/MacOS/\n";
 		};
 /* End PBXShellScriptBuildPhase section */
 
@@ -2650,6 +2650,7 @@
 				MTL_ENABLE_DEBUG_INFO = YES;
 				ONLY_ACTIVE_ARCH = YES;
 				SDKROOT = macosx;
+				SWIFT_ACTIVE_COMPILATION_CONDITIONS = "NS_FOUNDATION_ALLOWS_TESTABLE_IMPORT DEBUG";
 				VERSIONING_SYSTEM = "apple-generic";
 				VERSION_INFO_PREFIX = "";
 			};

TestFoundation/TestFileManager.swift

@@ -7,10 +7,12 @@
 // See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
 //
 
-#if !DEPLOYMENT_RUNTIME_OBJC && (os(Linux) || os(Android))
-@testable import Foundation
-#else
-@testable import SwiftFoundation
+#if NS_FOUNDATION_ALLOWS_TESTABLE_IMPORT
+    #if (os(Linux) || os(Android))
+        @testable import Foundation
+    #else
+        @testable import SwiftFoundation
+    #endif
 #endif
 
 class TestFileManager : XCTestCase {
@@ -35,13 +37,18 @@ class TestFileManager : XCTestCase {
             ("test_temporaryDirectoryForUser", test_temporaryDirectoryForUser),
             ("test_creatingDirectoryWithShortIntermediatePath", test_creatingDirectoryWithShortIntermediatePath),
             ("test_mountedVolumeURLs", test_mountedVolumeURLs),
-            ("test_XDGStopgapsCoverAllConstants", test_XDGStopgapsCoverAllConstants),
         ]
 
-#if !DEPLOYMENT_RUNTIME_OBJC
+#if !DEPLOYMENT_RUNTIME_OBJC && NS_FOUNDATION_ALLOWS_TESTABLE_IMPORT
         tests.append(contentsOf: [
+            ("test_xdgStopgapsCoverAllConstants", test_xdgStopgapsCoverAllConstants),
             ("test_parseXDGConfiguration", test_parseXDGConfiguration),
             ("test_xdgURLSelection", test_xdgURLSelection),
+        ])
+#endif
+        
+#if !DEPLOYMENT_RUNTIME_OBJC
+        tests.append(contentsOf: [
             ("test_fetchXDGPathsFromHelper", test_fetchXDGPathsFromHelper),
         ])
 #endif
@@ -965,7 +972,9 @@ class TestFileManager : XCTestCase {
     }
 
 #if !DEPLOYMENT_RUNTIME_OBJC // XDG tests require swift-corelibs-foundation
-    func test_XDGStopgapsCoverAllConstants() {
+    
+    #if NS_FOUNDATION_ALLOWS_TESTABLE_IMPORT // These are white box tests for the internals of XDG parsing:
+    func test_xdgStopgapsCoverAllConstants() {
         let stopgaps = _XDGUserDirectory.stopgapDefaultDirectoryURLs
         for directory in _XDGUserDirectory.allDirectories {
             XCTAssertNotNil(stopgaps[directory])
@@ -1076,6 +1085,9 @@ VIDEOS=StopgapVideos
         assertSameAbsolutePath(_XDGUserDirectory.publicShare.url(userConfiguration: configuration, osDefaultConfiguration: osDefaults, stopgaps: stopgaps), home.appendingPathComponent("SystemPublicShare"))
         assertSameAbsolutePath(_XDGUserDirectory.music.url(userConfiguration: configuration, osDefaultConfiguration: osDefaults, stopgaps: stopgaps), home.appendingPathComponent("StopgapMusic"))
     }
+    #endif // NS_FOUNDATION_ALLOWS_TESTABLE_IMPORT
+    
+    // This test below is a black box test, and does not require @testable import.
 
     enum TestError: Error {
         case notImplementedOnThisPlatform

lib/script.py

@@ -124,7 +124,7 @@ def generate_products(self):
         swift_flags += """
 TARGET_SWIFTEXE_FLAGS = -I${SDKROOT}/lib/swift/""" + Configuration.current.target.swift_sdk_name + """  -L${SDKROOT}/lib/swift/""" + Configuration.current.target.swift_sdk_name + """ """
         if Configuration.current.build_mode == Configuration.Debug:
-            swift_flags += "-g -Onone -enable-testing "
+            swift_flags += "-g -Onone -enable-testing -DNS_FOUNDATION_ALLOWS_TESTABLE_IMPORT "
         elif Configuration.current.build_mode == Configuration.Release:
             swift_flags += " "
         swift_flags += Configuration.current.extra_swift_flags