MSTest v3 - v4 Migration Migrate a test project from MSTest v3 to MSTest v4. The outcome is a project using MSTest v4 that builds cleanly, passes tests, and accounts for every source-incompatible and behavioral change. MSTest v4 is not binary compatible with MSTest v3 -- any library compiled against v3 must be recompiled against v4. First Action Inspect the supplied project and source before searching the web or answering from memory. Classify the request as a focused source fix, runtime behavior change, CI discovery issue, compatibility question, or full migration, then follow the matching r…