[swift-evolution] adding automated-testing of uncompilable features in XCTest

Benjamin Spratling bspratling at mac.com
Thu Dec 15 00:37:01 CST 2016

	Do you see this working with the package manager as well?

> On Dec 14, 2016, at 7:42 AM, Jeremy Pereira <jeremy.j.pereira at googlemail.com> wrote:
> The Swift compiler can give you the information that you want. 
> Here is what you can do:
> Write a Swift source file that creates an instance of the type you want to test and then tries to access each of the private members. 
> Write a shell script to compile this source file i a module with the file the type is defined in. Have it capture all the error messages by redirecting stderr and then count them. If it doesn’t have the right number, have the shell script emit a message that looks like a Swift error message.
> Install the script in a run script build phase. Now you will get an error every time one of your private properties or methods loses its access modifier.
> Personally, I wouldn’t bother. Any test to make sure that private members are private requires a separately maintained list of the private members. If somebody isn’t disciplined enough to add the word “private” to the beginning of a definition, they almost certainly aren’t going to bother updating a separate list. And the consequences of omitting “private” are only that the module has visibility of it. That’s not a huge deal. 

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