> He fed only the API and the test suite to Claude and asked it to reimplement the library from scratch.
From GPL2:
> The source code for a work means the preferred form of the work for making modifications to it. For an executable work, complete source code means all the source code for all modules it contains, plus any associated interface definition files, plus the scripts used to control compilation and installation of the executable.
Is a project's test suite not considered part of its source code? When I make modifications to a project, its test cases are very much a part of that process.
If the test suite is part of this library's source code, and Claude was fed the test suite or interface definition files, is the output not considered a work based on the library under the terms of LGPL 2.1?
Legally, using the tests to help create the reimplementation is fine.
However, it seems possible you can't redistribute the same tests under the MIT license. So the reimplementation MIT distribution could need to be source code only, not source code plus tests. Or, the tests can be distributed in parallel but still under LGPL, not MIT. It doesn't really matter since compiled software won't be including the tests anyways.