Frequently Asked Questions

What is Fuchsia CTF?

Please see the CTF overview for an explanation of what CTF is.

What is the CTF release schedule?

CTF has multiple releases with separate cadences:

Release Schedule
Canary ~4 hrs
Milestone ~6 weeks

The canary release is created when new canary releases of the Fuchsia platform are created. Likewise, milestone releases are created when new milestone releases of the Fuchsia platform are created.

Milestone branches (e.g. releases/f7) often receive cherry picks. When this happens, a new CTF for that milestone is generated and automatically rolled into CI/CQ.

When will my CTF test start running on CQ?

The tip-of-tree version of your test will immediately begin running on CI/CQ. This version of the test does not guarantee backward compatibility.

When the next CTF release is cut, it will contain a snapshot of your test from tip-of-tree which will begin running as soon as that CTF release rolls into CI/CQ. This version of your test guarantees backward compatibility.

See this section above for the release schedule.

What test environment does CTF use in CQ?

See go/fuchsia-builder-viz. Look for builders whose names end in "-cts".

At minimum, all CTF tests run on the core.x64 image in the Fuchsia emulator.

How can I tell which version of a CTF test is failing?

CQ may run several versions of the same CTF test at a time: The version from tip-of-tree, from the latest canary release, and from a previous milestone release.

CTF test packages are named after the Fuchsia API level they test:

| Version | Example package name | |-|-| | tip of tree | my_test | | canary | my_test_apicanary | | API level $N | my_test_api$N |

The full package URL will look something like:


How do I reproduce a CTF test failure locally?

To build and run a specific version of a test, you can use the following examples:

# Build the test.
fx set //sdk/ctf/tests/fidl/fuchsia.example:tests
fx build

# Run all versions.
fx test

# Run the version for API level 20.
fx test fuchsia.example_test_api20

Please also see this guide about running Fuchsia tests.

What do I do if a CTF test is blocking my CL?

This is a sign that your CL is breaking a part of the platform surface area. Please verify that there are no projects in downstream repositories that rely on the APIs and ABIs modified by your CL. If so, you will need to make a soft transition. The general workflow is as follows:

  1. Submit a CL that introduces the new behavior in your change and verify that the tip-of-tree version of the CTF test passes.
  2. Notify any downstream SDK Users of the upcoming breaking change, ask them to migrate and depend on the new behavior.
  3. Wait for the next CTF release to roll into CI/CQ.
  4. Submit a CL to remove the old behavior.

Are there any examples of CTF tests?

See //sdk/ctf/examples and //sdk/ctf/tests.

When and why should I write a CTF test?

You should write a CTF test if the software being tested is in the public or partner SDK category.

How do I remove a CTF test?

See the section in the contributing guide on removing tests.

Additional questions

For additional questions please reach out to or file a bug in the CTF bug component.