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 row below. A clean compile does not exclude this skill: discovery failures, TestContext lifecycle exceptions, and test-history changes are runtime migration failures.

When to Use