---
title: Configuration
description: Set the CI time budgets for flaky test detection and turn on auto-quarantine.
---

Every Test Engine setting lives on one page of the dashboard:
**Test Engine > Flaky Tests >
[Configuration](https://dashboard.mergify.com/test-engine/configuration)**.
Pick a repository in the selector at the top right. The settings apply to that
repository only, except the ones under **Global**.

Changing a setting requires write access to the repository. Without it, the page
shows the current values but you cannot change them.

## Global

The settings in this section apply to every repository of the organization.

**Data Retention** shows how long Mergify keeps your test runs, which depends on
your plan. Mergify judges test health from the runs it keeps, so a longer
history makes the [health status](/test-engine/health) more accurate and
catches flaky tests that fail only once in a while.

## Native Flaky Detection

Mergify's test framework plugins rerun your tests to find flaky ones, within
the CI time budgets you set in this section. Without a plugin, these settings
have no effect: see the
[test framework configuration](/test-engine#test-framework-configuration) to
install one.

<Image
  src={NativeFlakyDetectionScreenshot}
  alt="Native Flaky Detection section with the Prevention Budget and Detection Budget sliders"
/>

- **Prevention Budget**: CI time Mergify can spend rerunning the tests a pull
  request adds, to catch flaky tests before they merge.
  [Prevention](/test-engine/prevention) reruns tests within this budget.

- **Detection Budget**: CI time Mergify can spend rerunning tests that failed
  recently or do not have enough runs yet, to tell whether they are flaky.
  Detection [reruns unhealthy tests](/test-engine/detection#rerunning-unhealthy-tests)
  within this budget.

Each budget is a percentage of a typical test run. At 10%, Mergify may add up to
a tenth of that run's duration to each run. The line under the slider shows how
much time that is for your repository.

A repository starts with no budget saved, so Mergify spends no extra CI time
until you set one. Move the sliders, then click **Save Changes**. Both budgets
are saved together, and **Discard** drops the changes you have not saved yet.

The badge next to each budget reads **Active** once a plugin has recently used
that budget, and **Not Used Yet** otherwise.

## Auto-quarantine

Auto-quarantine lets Mergify quarantine tests without anyone doing it by hand.
See [Mitigation](/test-engine/mitigation#auto-quarantine) for what quarantine
does to a test, and
[when Mergify quarantines a test itself](/test-engine/quarantine#when-mergify-quarantines-a-test-itself)
for the evidence it waits for.

<Image src={AutoQuarantineScreenshot} alt="Auto-quarantine section with its main switch and its two options" />

- **Quarantine Flaky Tests Automatically**: the main switch. Once it is on,
  Mergify quarantines a flaky test as soon as it has enough evidence.

- **Also Quarantine Broken Tests**: quarantines tests that fail every time as
  well. They stop blocking pull requests, but they also stop catching real bugs
  until someone fixes them.

- **Unquarantine Recovered Tests Automatically**: once a test that Mergify
  quarantined is
  [healthy again](/test-engine/mitigation#leaving-quarantine-automatically),
  Mergify takes it out of quarantine. When it is off, the test stays
  quarantined until someone unquarantines it.

The two options can only be changed while the main switch is on. The main
switch asks you to confirm before it turns auto-quarantine on or off; the two
options take effect as soon as you flip them, with no save step.
**View change history** opens the activity log for auto-quarantine changes.

Auto-quarantine is available on plans that include quarantine. On other plans,
the section shows its switches turned off and grayed out.