How to migrate a test suite without interrupting regression testing
Test-suite migration is usually postponed for one reason. Not because it is unclear what needs to be done, but because nobody is comfortable with a period in which no testing takes place.
The assumption goes like this: the old suite is switched off, the new one takes three months to write, and releases go out blindly in the meantime. Nobody wants to sign off on that, so the migration is postponed until the next quarter. The cycle continues until the suite reaches the end of its life on its own.
It does not have to happen this way.
Common problem: reliable checks are missing during migration
A suite is not one indivisible unit that can only be migrated all at once. It is a collection of scenarios, and each has a different weight. Purchases and payments keep your business running. Checking the text in the footer does not.
When you look at the suite this way, moving everything at once no longer makes sense. You can migrate it in parts, and each completed part can start working immediately. You do not have to wait for the entire suite to be finished.
How to maintain checks during the migration
Analysis and order. First, we determine what the suite actually covers. Some tests are dead: they verify a feature that no longer exists or have been skipped for a long time. We do not migrate those at all. We rank the rest by how much it hurts when the scenario fails.
A pilot on one scenario. We use one important journey to verify the new suite’s architecture and stability before anything else is migrated. If something in the design is wrong, we discover it in one test, not two hundred.
Gradual migration. We move scenario by scenario in priority order. The first migrated scenario enters the pipeline immediately, not only at the end of the project. You see value from the beginning rather than only at handover.
Both suites temporarily run side by side. Until the migration is complete, the old suite can check scenarios that have not yet moved, while the new one checks those that have already been verified. A scenario map must continually confirm the retained coverage, the stability of both suites needs to be monitored, and gaps need to be minimised. This does not automatically mean the same level of confidence on every day of the migration.
The overlap is useful in its own right. When the same scenario runs in the old and new suites and the results differ, the test, data, environment, timing, and expected outcome need to be investigated. The difference alone does not determine which suite is correct.
Retiring the old suite. The old suite is switched off only after everything important has been migrated and the new suite runs reliably. Not before.
We used this approach when replacing an existing test automation solution, with the old and new suites running in parallel until the replacement had been verified.
What a gradual migration gives you
A migration during which you do not have to plan to disable every regression check for the entire transition. Risk remains managed according to which scenarios are still in the old suite and which have already been verified in the new one.
If priorities change, the migration can be paused after the work in progress is completed. Migrated and verified scenarios remain in the new suite, while the others stay in the old one. The team must, however, maintain an overview of scenario ownership and both codebases in operation.
We design the new suite for easier maintenance, for example with an appropriate layer of page or component objects, stable identifiers, and separate test data. The architecture itself does not replace ongoing maintenance when the application changes.
What to watch out for when estimating
The duration depends on the number and complexity of the scenarios, the state of the original code, dependencies, and environment readiness. Some obsolete or duplicate tests may not need to be migrated, but an agreed scenario map needs to confirm that the intended coverage has been retained.
Next step
Show us what you have today and tell us which journeys must remain covered throughout the transition. Contact us and we will propose the migration order, a coverage map, and a way to minimise gaps during the migration.