# Hermetic Testing

**URL:** <https://club.ministryoftesting.com/t/hermetic-testing/86034>\
**Category:** Discussions\
**Tags:** automation, career-development, testing\
**Created:** [23 July 2025 06:25 UTC](https://club.ministryoftesting.com/t/hermetic-testing/86034 "2025-07-23T06:25:51Z")\
**Posts on this page:** 1\
**Showing post:** 12

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**Author:** ![canofcam](https://avatars.discourse-cdn.com/v4/letter/c/848f3c/32.png) [@canofcam](https://club.ministryoftesting.com/u/canofcam)\
**Post date:** [29 July 2025 09:40 UTC](https://club.ministryoftesting.com/t/hermetic-testing/86034/12 "2025-07-29T09:40:42Z")

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Hermetic testing to me is a method for ensuring that tests run consistently and offer a consistent value. If we apply the idea of Hermetic Testing to only the data element of a tests requirements, we can understand what this means.

Imagine there are three ways to handle data in our testing:

1. Our tests can create their own data and then test that data
2. Our tests could expect data to already exist, and choose something valid at random
3. Our tests can expect specific data to already exist, and use the exact same data everytime they run

The third bullet point is how I imagine Hermetic Testing. `Test-001` expects `[item]` to already exist, it navigates directly to the UID of `[item]` and performs the test.

This is a more scientific method of testing when compared to 1. and 2., because they inherently have risk built into them.

1. In **approach 1** , if the data creation step fails, the test fails without even reaching the point it’s meant to test.
2. In **approach 2** , if the assumed data isn’t present or changes unexpectedly, the test again fails for reasons unrelated to its actual assertions.
3. In **approach 3** (Hermetic Testing), the framework **pre-seeds** the required data in a known, stable state. As a result, tests _should_ always run the same and _in theory_ only fail when there’s a real bug.

This, to me, is the purpose of Hermetic Testing: to build a regression pack that executes _exactly_ the same way, _every single time_, so that when a test fails, we can trust that something _really_ broke.

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