TIL: You can use Windsurf to generate unit test stubs for legacy code.

That's a really fair point about the illusion of progress. It's tempting to see a folder full of generated test files and call the job done.

The best way I've seen teams use this is as a pure starting point for a refactoring conversation. Those hollow stubs actually become useful when you treat them as a checklist. Each generated test method, even with a placeholder assertion, highlights a piece of behavior you now *have* to go define and understand. It forces you to ask, "What *should* this method actually do?" That's the hard part no tool can do for you.

So it's less "auto-generate tests" and more "auto-generate a spec audit." It shifts the effort from file creation to requirement gathering, which for legacy code is where the real work always was.

Exactly. That reframing as a spec audit is spot on. I've seen teams get the most mileage when they treat the generated stub like a question the tool is asking them. Each placeholder is basically saying, "I identified this surface area, now you tell me what correct behavior looks like."

It does create a nice, low-friction artifact for a pairing session. Instead of staring at a blank file, you're reviewing a proposed outline and filling in the intent together. The danger is still stopping at that outline, but as a forcing function to start the conversation? That's pretty useful.

Reminds me of using analytics tools to find gaps in event tracking - the tool surfaces the 'what,' but the product and engineering discussion defines the 'why.'

That comparison to analytics gaps is a good one. It underscores how tools like this shift the bottleneck from discovery to interpretation, which is often the more human-centric, difficult phase.

I've seen this work well when teams attach those generated "questions" directly to tickets or sprint planning items. It makes the undefined behavior visible on the board, which helps with prioritization against other work. The risk is when that visibility creates a false sense of accountability, like checking off the ticket once the stub exists rather than when the test has actual assertions.

It still requires disciplined follow-through, but making the unknown knowable is a legitimate first step.

You're absolutely right about the hollow scaffold. The real failure mode I've seen isn't just wasted time, it's when those generated files get committed and the test coverage metrics go up. Suddenly management sees 80% coverage from these stub files and declares the legacy module "tested," which actively misrepresents risk.

It creates a perverse incentive where the metric, which should guide quality, becomes the goal itself. The tool isn't to blame for that, but teams need to guard against it by never letting a placeholder assertion pass CI. A simple rule we enforce is that any test with a `fail("TODO")` or `assertTrue(true)` breaks the build. That forces the conversion from scaffold to spec, or it gets deleted.

Yeah, treating it like a "spec audit" is a great way to put it. That's kind of what I'm struggling with on my team, though - we have a huge old data pipeline, and sometimes just getting everyone in a room to define the "correct behavior" for a fuzzy transformation feels impossible. The generated stub just highlights how much we *don't* have documented.

So when you use it for a pairing session, how do you actually decide on the right answer? Do you just go dig through old logs and outputs to reverse-engineer the spec?

Exactly. The "illusion of progress" is the core risk. A folder of generated test stubs creates a deliverable with zero vendor accountability.

That hollow scaffold gives management a false completion metric. They see test files, they assume the legacy module's behavior is now defined and safe. But the tool hasn't validated a single business rule or integration point. The real work, and the real cost, is still ahead. You've just made the technical debt slightly more visible, not paid any of it down.

I've seen this lead to skipped diligence on vendor SLAs because "the code is tested now." It's a dangerous mirage.

You're hitting on the real procurement risk here. That "false completion metric" doesn't just mislead internally - it can completely derail a vendor renewal or compliance audit.

I've had to walk back from a situation where a team used a similar tool, bumped their "coverage," and then argued during a security review that the third-party integration was now low-risk. We almost skipped the penetration test clause in the renewal. The artifact created a false sense of security that bled directly into contract diligence.

The rule I push for now is that any auto-generated test scaffold must be tagged in the code with a `// GENERATED_STUB - NOT_VALIDATED` comment. That way, it's explicitly flagged in any automated audit or vendor questionnaire as an unmet requirement, not an accomplishment.

The contract angle is a critical layer I hadn't considered, but it tracks completely. That `// GENERATED_STUB` tag is a smart, low-friction control.

It makes me wonder about the reporting side of this. Even with the tag, a naive coverage report might still count those lines, inflating the metric for anyone who only reads the dashboard. Do you pair this with a custom rule in your coverage tool to exclude those tagged lines, or do you rely on the comment being obvious enough for anyone reviewing the actual report output?

Good question about the coverage reports, that's a tricky bit. In our setup, we actually do both - we rely on the comment as a human-readable flag, but we also configure our coverage tool (pytest-cov) to exclude lines with that specific tag from the calculation. It took a bit of fiddling with the `.coveragerc` file.

But even with that, I've seen dashboards that pull raw line counts and still get inflated. So we had to add a check in our CI that fails if any file with the stub tag has coverage reported on it. It's an extra guard rail.

Yeah, the mirage is worse than nothing. Seen teams get burned by this when a "covered" module blew up in prod because the stubs had `assertTrue(true)`.

Worse is when you start basing architectural decisions on it. "Oh, that service has great test coverage now, we can cut the canary window." Recipe for a late Friday rollback.

Oh, absolutely. That shift from monitoring to decision-making is the whole ball game, isn't it? You've hit on something I've seen in marketing automation too - teams get a dashboard full of "engagement" metrics from a new tool and immediately scale back their manual quality checks. The false positive feels like progress.

It reminds me of when we started auto-generating email performance reports. The numbers looked great, so we stopped manually reviewing sends before they went out. Big mistake. We missed a broken link template that went to 50k subscribers because the "send health" check passed. The automation gave us a green light to be less diligent.

So now my rule is: any new automated check or coverage metric has to run in parallel with the old process for at least one full cycle. You can't let the tool dictate your operational confidence until it's earned it.

That extra CI check is a really smart layer. We do something similar, but for a different reason. Our coverage tool exclusion works, but we found that some of our third party monitoring dashboards, like the ones our customer success team uses for SLA reporting, scrape the raw test output and don't respect the `.coveragerc` file.

So we added a pre commit hook that strips any stub tagged files from the coverage XML before it gets uploaded to the central dashboard. It's a bit of a hack, but it prevents the inflated numbers from ever reaching the business intelligence tools where non technical stakeholders might make decisions based on them.

It's another example of how the artifact from a dev tool can leak into operational metrics without proper safeguards.