AssertShift

Your code changed. Did your tests? AssertShift is a developer workflow built around IBM Bob 2.0 that helps test suites evolve when software behavior changes. A passing test suite can create false confidence. Existing tests may still be green while asserting outdated behavior too weakly, or they may completely miss newly introduced requirements. AssertShift addresses this by giving Bob the approved behavior change, implementation, and existing tests, then asking it to reason about how the test suite should change. In the prototype, Bob identified 2 STALE tests whose assertions no longer adequately constrained the new behavior and 4 MISSING coverage areas introduced by the updated requirements. Bob then evolved the suite by tightening 2 existing tests and adding 11 new tests, growing the suite from 8 to 19 tests. AssertShift does not stop at generating tests. It verifies whether the evolved suite is actually stronger. A deterministic verification matrix runs the baseline and evolved suites against the correct implementation and three controlled single-defect mutants. All three mutants escape the original green baseline suite, while all three are detected by the evolved suite, with zero infrastructure errors. The result is a reproducible workflow that connects requirements → test intent → test evolution → executable evidence. Mutation testing is used as the proof mechanism, not the product itself. The core idea is requirements-driven test-suite co-evolution: detecting when tests no longer evolve with the behavior they are supposed to protect.