Hi! I must be missing something. I am creating a MacOS dynamic library using Xcode. I have created the library as follows: File->New Project then choose macOS 'Library' in Frameworks and Libraries. I give the Product Name "TestLib". Framework: STL (C++ Library) Type: Dynamic This creates a default library project, with one exported class 'TestLib'. There's a method "HelloWorld". And this suffices for my issue. To be able to test my dynamic library, I want to use an XCtest target. So in the project settings, I select '+', and add a 'Unit Testing Bundle': Product name: TestLibTests Language: Swift Testing System: XCTest Project: TestLib Target to be tested: TestLib I press finish, and my test target is created. Now, I think I need to have a module map. So I Add New File From Template', and choose 'Module Map'. A 'module.modulemap' is created. In the module map file, I name the module 'TestLib', and header 'TestLib.h'. So far, everything makes sense, and no errors. But here it comes... When I want to make a testcase, I need to import the module. I first built the dylib library, to make sure it's built without errors and exists. Then I switch to the TestLibTests target and want to write my first test. Simply creating an object from the TestLib class. For that, I have to import the module, so I write 'import TestLib' after the 'import XCTest' at the top. And here is where I'm stuck. No matter what I do, Xcode just gives me the error 'No such module TestLib'. This should just work, right? I should be able to unit test my library. I have spent 2 days reading the internet and trying many suggestions, but I just can't get it to work. I am currently working with Xcode 26 beta. But I tried with Xcode 16.4 and that has the same issue. What am I missing?

I am encountering a strange issue. I have a class that manages a selection of generic items T in an Array. It's a work in progress, but I'l try to give a gist of the setup. class FileManagerItemModel: NSObject, Identifiable, Codable, NSCopying, Transferable, NSItemProviderReading, NSItemProviderWriting { var id: URL static func == (lhs: FileManagerItemModel, rhs: FileManagerItemModel) -> Bool { lhs.fileURL == rhs.fileURL } var fileURL: URL { FileManagerItemModel.normalizedFileURL(type: type, rootURL: rootURL, filePath: filePath) } init(type: FileManagerItemType, rootURL: URL, fileURL: URL) { self.type = type self.rootURL = rootURL self.filePath = FileManagerItemModel.filePathRelativeToRootURL(fileURL: fileURL, rootURL: rootURL) ?? "[unknown]" self.id = FileManagerItemModel.normalizedFileURL(type: type, rootURL: rootURL, filePath: filePath) } } The class that manages the selection of these FileManagerItemModels is like so: @Observable class MultiSelectDragDropCoordinator<T: Hashable>: ObservableObject, CustomDebugStringConvertible { private(set) var multiSelectedItems: [T] = [] func addToSelection(_ item: T) { if !multiSelectedItems.contains(where: { $0 == item }) { multiSelectedItems.append(item) } } ... } My issue is that the check if !multiSelectedItems.contains(where: { $0 == item }) in func addToSelection fails. The if is always executed, even if multiSelectedItems contains the given item. Now, my first thought would be to suspect the static func == check. But that check works fine and does what it should do. Equality is defined by the whole fileURL. So, the if should have worked. And If I put a breakpoint in func addToSelection on the if, and type po multiSelectedItems.contains(where: { $0 == item }) in the debug console, it actually returns true if the item is in multiSelectedItems. And it properly return false if the item is not in multiSelectedItems. Still, if I then continue stepping through the app after the breakpoint was hit and I confirmed that the contains should return true, the app still goes into the if, and adds a duplicate item. I tried assigning to a variable, I tried using a function and returning the true/false. Nothing helps. Does anyone have an idea on why the debugger shows one (the correct and expected) thing but the actual code still does something different?