I recently observed some protocol changes to FileDocument in the Xcode 12 beta 6 release. It was easy enough to get my app working again, but I am having trouble updating my tests.

In my tests I programmatically create instances of my Document to verify it will migrate older file formats properly. With the updated FileDocument protocol the init looks something like:

    init(configuration: ReadConfiguration) throws {
        guard let data = configuration.file.regularFileContents,
              let string = String(data: data, encoding: .utf8)
        else {
            throw CocoaError(.fileReadCorruptFile)
        }
        text = string
    }

How do I initialize a ReadConfiguration in a test?

When I try to do it I get a error:

// ERROR: 'PeopleDocument.ReadConfiguration' (aka 'FileDocumentReadConfiguration') 
// cannot be constructed because it has no accessible initializers

More info can be found on this GitHub issue:

https://github.com/zorn/VersionedFilesDemo/issues/1