Raise Test Coverage with AI
Test coverage is the work everyone agrees is important and nobody has time for. The critical path that's never had a unit test, the service that's grown three branches of logic with one happy-path test, the module that breaks in a different way every quarter — they sit at the bottom of the backlog because writing tests for existing code is tedious and never urgent until it is.
Codowave is an autonomous AI engineer that raises coverage where it counts. It finds untested paths, writes tests that match your suite's conventions, runs them, and opens a PR — without you assigning a developer to spend a sprint on it.
Start your 5-day trialThe Coverage Problem
Most teams know their coverage number is lower than they'd like, and they know exactly which modules are dragging it down. The blocker isn't knowledge — it's time. Writing tests for existing, working code feels low-value in the moment, so it loses every prioritization battle to feature work and bugs. The result: the riskiest, least-tested code stays that way until it causes an incident.
This is a near-perfect fit for autonomous work. Coverage tasks are well-defined ("add tests for PaymentService.calculateTax"), verifiable (the tests either pass or they don't), and bounded (one module at a time).
How Codowave Raises Coverage
Step 1: Point It at the Gaps
Create issues for the modules you want covered — or label existing ones (test-coverage, tech-debt). Codowave reads them like any other backlog work. You can scope it to a directory or package in a monorepo so it focuses where coverage matters most.
Step 2: It Studies Your Test Conventions
Before writing anything, Codowave learns how your suite is built — describe/it vs test, your fixture and mock patterns, how you structure assertions, which helpers you reuse. The tests it writes look like your team wrote them, not like a generic template.
Step 3: It Writes and Runs the Tests
Codowave writes tests for the untested paths, runs your suite to confirm they pass, and checks that they actually exercise the code (not just assert true). The Tester agent verifies the additions before the PR opens.
Step 4: It Opens a Reviewable PR
You get a PR with the new tests, the coverage delta, and the run output attached. Review it like a teammate's — the tests are readable, named to your conventions, and scoped to one module.
What Codowave Handles Well Here
| Coverage Task | Example | Performance |
|---|---|---|
| Pure function tests | "Add tests for calculateTax edge cases" | Strong |
| Service method coverage | "Cover all branches of OrderService.fulfill" | Strong |
| Validation logic | "Test the email and phone validators" | Strong |
| Error-path coverage | "Add tests for the failure cases in retryWithBackoff" | Strong |
| Regression tests | "Add a test reproducing issue #412 before fixing it" | Strong |
| Integration tests | "Cover the orders endpoint end to end" | Moderate |
| UI snapshot tests | "Snapshot the settings page states" | Moderate |
Real Numbers: What to Expect
Based on typical Codowave usage on coverage work:
- Modules covered per week: 8–15, depending on size and complexity
- PR merge rate (tests pass, human-approved): 70–85% — coverage work merges cleanly more often than feature work because it's well-bounded
- Coverage lift: teams commonly move a lagging module from one happy-path test to full-branch coverage in a single PR
- Cost per merged PR: approximately $1–3 on the Pro plan
Coverage is one of the highest-merge-rate categories Codowave runs, precisely because the success condition is objective.
What It Won't Do
- Chase a coverage percentage for its own sake. It writes tests that exercise real behavior, not assertion-free filler that games the number.
- Test untestable code without flagging it. If a path can't be reached or a dependency can't be mocked cleanly, it says so rather than writing a hollow test.
- Rewrite your test framework. It works within the suite and conventions you have.