Continuous integration

edit

A snapshot that changes on a build server is a failure to report, not a file to update. Snapshots are therefore never updated, and no merge tool is started, in these environments, whatever the update strategy, including Overwrite and a strategy set with SNAPSHOTTESTING_STRATEGY:

A build server or another non-interactive environment, detected by the variables the major build servers set: CI, TF_BUILD, GITHUB_ACTION, GITLAB_CI, JENKINS_URL, TEAMCITY_VERSION, APPVEYOR, TRAVIS_BUILD_ID, GO_SERVER_URL, and MyGet's BuildRunner. Containers (DOTNET_RUNNING_IN_CONTAINER) and WSL (WSL_DISTRO_NAME) are treated the same way, as no diff tool is expected to show up there.
A continuous testing runner: NCrunch, ReSharper or Visual Studio Live Unit Testing.
An LLM agent, such as Claude Code, Codex, GitHub Copilot or Cursor, detected by Meziantou.Framework.LLMContext. An agent that runs the tests sees the failure and the actual files, and a person decides whether to approve them.

The test fails as with Disallow, the actual files are written, and the failure message says which environment was detected.

Review the actual files of a CI run

The actual files are written on the build server too. Publish the **/__snapshots__/*.actual.* files as build artifacts when a run fails: you can download them, review them, and copy them over the verified files of your branch.

Allow updates in such an environment

To allow updates anyway, for instance in a dev container where you run the tests yourself, set the SNAPSHOTTESTING_AUTODETECT_CONTINUOUS_ENVIRONMENT environment variable to false (or 0, no, off), or set AutoDetectContinuousEnvironment to false:

var settings = SnapshotSettings.Default with
{
    AutoDetectContinuousEnvironment = false,
};

The update strategy then applies as on a developer machine.