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Dependabot

This repo contains manifest files for various package managers and is used to perform end-to-end tests for Dependabot.

How does this work?

Dependabot CLI has the capability to generate and consume test files.

To generate a test, run dependabot update go_modules dependabot/smoke-tests -o my-test.yml. This will create my-test.yml containing the inputs you provided, plus some ignore conditions to make the test more reproducible, and also contain the outputs the CLI recorded.

To run the test, run dependabot test -f my-test.yml. This will run Dependabot with the inputs provided in the test, and assert the outputs match what was previously recorded.

Caching

To further aid in reproducibility, the CLI can instruct the Proxy to enable caching with the --cache tmp/cache option. Simply pass that along with a path to use for the cache during testing, and the Proxy will dump messages it received there.

If there are already cache files present, the Proxy will use them during the run instead of making a network call. Neat!

Checking failures

Sometimes a test will fail. To more easily check the difference, use the -o option to write the new outputs for an easy diff:

dependabot test -f input.yml -o output.yml
diff input.yml output.yml

Or if the file is checked into Git, just overwrite the existing file:

dependabot test -f test.yml -o test.yml

Workflows

This repo has several workflows used to manage the caches that are stored as build artifacts:

  • Cache one
    • This allows us to run a single smoke test and cache the results.
  • Cache all
    • This runs all of the smoke tests and cache the results, which is useful when a large change happens.
  • Smoke
    • This test downloads the cache from the build artifacts before running each test in parallel. This was designed to run after each Pull Request.

To see the percentage of caching on each test, go to the Smoke tests summary view. If the test has low cache coverage then it is more likely to fail in the future. Rerun the Cache one workflow to recache it, or debug why it is uncachable.

Regenerating tests

Sometimes after a test has been uncached for a while, it will break because the dependencies have changed, and recaching won't fix it. Also some package-managers seem to get around the caching after a while.

In this case we will need to regenerate the failing test locally with dependabot test -f tests/smoke-bundler.yaml -o tests/smoke-bundler.yaml then push it up, and recache that test with the "Cache" workflows.

Where possible try to add additional ignore_conditions and allowed_updates so even when uncached the tests will not fail.

For convenience there's a script/run-all.sh which will regenerate all of the tests.

How to add new tests

To create a new test:

  1. Add new manifest files, and push the commit to this repo in a branch
  2. Run dependabot update $ecosystem dependabot/smoke-tests --directory $dir --commit $previous_commit_sha -o tests/smoke-$ecosystem-$testname.yaml substituting the appropriate values:
    • $ecosystem is the directory name in dependabot-core for the ecosystem
    • $dir is the relative path to the manifest files
    • $previous_commit_sha is the commit SHA that contains the manifest files under test
    • $testname is a descriptive name for the test
  3. Commit the resulting test
  4. Run the Cache-One Workflow to cache the test, so it won't break due to dependency changes before the PR merges
  5. When merging, be sure to make a merge commit, don't squash or rebase! This will change the $previous_commit_sha.

The reason we do it this way is the commit under test is in the API calls in the output section. So we must pin the test to a commit or a change to this repo will break all the tests.

Also, the manifests must be pushed up before the test can be run, because Dependabot will attempt to fetch them.

If you are contributing from a fork, perform the steps above replacing dependabot/smoke-tests with your fork, and we can do the rest.

Secrets

To keep secrets out of test files, the CLI can use environment variables instead:

credentials:
  - type: npm_registry
    registry: https://npm.pkg.github.com
    token: $MY_TOKEN

ARM64 machines

Since we currently don't produce ARM images, it is recommended you use Codespaces to run and regenerate tests. It runs much faster than emulation!