🍲 Kettle::Jem::Appraisals

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kettle-jem-appraisals automates CI testing matrix generation for Ruby gems. It reads your gemspec, queries the RubyGems API to discover published versions of your runtime dependencies, detects Ruby-version seam points (where required_ruby_version changes), and produces:

• Modular gemfiles under gemfiles/modular/{gem}/{ruby_series}/v{version}.gemfile
• An Appraisals file for use with appraisal2
• Workflow strategy matrix snippets for GitHub Actions CI

If you want a lighter-weight DSL for the original appraisal gem, consider appraisal-matrix instead. kettle-jem-appraisals targets appraisal2 (which supports eval_gemfile, and all ruby versions), while appraisal-matrix targets appraisal (which does not support eval_gemfile, and only supports modern ruby).

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Works with JRuby
Works with MRI Ruby 4
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Compatible with MRI Ruby, and JRuby. CI workflows and Appraisals are generated for MRI Ruby 4.0.0+. This test floor is configured by ruby.test_minimum in .kettle-jem.yml and may be higher than the gem's runtime compatibility floor when legacy Rubies are not practical for the current toolchain.

The amazing test matrix is powered by the kettle-dev stack.

How kettle-dev manages complexity in tests

Gem	Source	Role	Total downloads
appraisal2	GitHub	multi-dependency Appraisal matrix generation
appraisal2-rubocop	GitHub	RuboCop Appraisal generator integration
kettle-dev	GitHub	development, release, and CI workflow tooling
kettle-jem	GitHub	Appraisals & CI workflow templates
kettle-soup-cover	GitHub	SimpleCov coverage policy and reporting
kettle-test	GitHub	standard test runner and coverage harness
rubocop-lts	GitHub	Ruby-version-aware linting
turbo_tests2	GitHub	parallel test execution

Available as part of the Tidelift Subscription.

Install the gem and add to the application's Gemfile by executing:

bundle add kettle-jem-appraisals

If bundler is not being used to manage dependencies, install the gem by executing:

gem install kettle-jem-appraisals

Configuration lives in .kettle-jem.yml under the appraisal_matrix key. Running --scaffold creates a starter config from your gemspec.

appraisal_matrix:
  # Global version selection mode (default: semver)
  # Per-gem overrides via the "mode" key on individual gem entries.
  mode: semver

  # Seconds before a resolved matrix is considered stale (default: 604800 = 7 days).
  # Use --force to bypass.
  freshness_ttl: 604800

  # Command to run in CI for each appraisal entry (default: "rake spec")
  exec_cmd: "rake spec"

  gems:
    # Tier 1: primary dependencies whose versions drive the matrix.
    # Each tier1 version is assigned to its optimal Ruby bucket.
    tier1:
      - name: activerecord
        # Optional requirements filter
        requirements:
          - ">= 6.1"
          - "< 8.0"
        # Optional exact-version allowlist, added on top of mode + requirements
        include_versions:
          - "8.0.1"
        # Optional exact-version denylist, removed from the final matrix
        exclude_versions:
          - "7.2"
      - name: mail
        mode: major  # per-gem mode override

    # Optional tier1_mode: default mode for all tier1 gems (overrides global mode)
    # tier1_mode: minor-minmax

    # Tier 2: secondary dependencies cross-producted with tier1.
    # Omit if your gem has only one primary dependency.
    tier2:
      - name: omniauth

    # Optional tier2_mode: default mode for all tier2 gems
    # tier2_mode: major

Each gem entry may further restrict the resolved version set with requirements. Values can be a string or an array of RubyGems requirement strings.

appraisal_matrix:
  gems:
    tier1:
      - name: activerecord
        mode: patch
        requirements:
          - ">= 7.1"
          - "< 7.2"
      - name: sequel
        requirements:
          - ">= 5.0"
          - "< 6.0"

Those filters apply both to version selection and to Ruby seam detection, so the generated buckets stay aligned with the versions you actually intend to test.

Each gem entry may also specify include_versions, an explicit allowlist of additional versions to union into the matrix.

appraisal_matrix:
  gems:
    tier1:
      - name: activerecord
        mode: semver
        requirements:
          - ">= 7.1"
          - "< 7.2"
        include_versions:
          - "6.0.9"
          - "8.0.1"

include_versions is additive:

• versions listed there are added even if they fall outside requirements
• versions listed there are added even if the selected mode would not normally include them
• the final generated matrix is the union of mode results, requirements filtering, and include_versions

Each gem entry may also specify exclude_versions, an explicit denylist of exact versions to remove from the resolved matrix.

appraisal_matrix:
  gems:
    tier1:
      - name: activerecord
        mode: semver
        requirements:
          - ">= 7.1"
          - "< 7.2"
        include_versions:
          - "6.0.9"
          - "8.0.1"
        exclude_versions:
          - "7.1.0"
          - "8.0.1"

exclude_versions is applied after mode selection, requirements, and include_versions, so the final set is:

• start with the versions selected by mode
• filter that set with requirements
• union in include_versions
• subtract exclude_versions

When a single major version has more than 9 minor releases (e.g. aws-sdk-dynamodb with 166 minors in major 1), semver mode automatically prunes to:

• The latest minor of that major
• Any minor that is the last before a Ruby version is dropped (Ruby-cutoff versions)

This prevents matrix explosion while preserving meaningful coverage.

All generated names are prefixed with kja- (kettle-jem-appraisals) so that regeneration can reliably identify and remove stale entries.

Format: kja-{tier1}-{t1ver}-{tier2}-{t2ver}-{ruby}

Common gem abbreviations are applied automatically:

Examples: kja-ar-7-1-oa-2-1-r3, kja-mail-2-8-r3 (tier1-only)

Rather than cross-producting every gem version with every Ruby series, each tier1 version is assigned to its optimal bucket — the newest Ruby where that version is the best (latest) choice. Gaps are backfilled automatically.

Example with activerecord:

Step 1 — Scaffold reads your gemspec and populates .kettle-jem.yml:

kettle-jem-appraisals --scaffold

Review the generated config: move gems between tier1 and tier2, set per-gem mode overrides, and remove any gems you don't want in the matrix.

Step 2 — Resolve queries RubyGems, computes the matrix, and writes files:

kettle-jem-appraisals --resolve

This generates:

• gemfiles/modular/{gem}/{ruby_series}/v{version}.gemfile — one per version×bucket
• Appraisals — references the modular gemfiles
• Runs bin/appraisal generate to create flat gemfiles (if binstub exists)

Without flags, the CLI auto-detects: scaffold if no versions are configured, resolve otherwise.

The resolved matrix is timestamped. Subsequent runs within freshness_ttl seconds are skipped unless --force is passed. Stale kja-* flat gemfiles from previous runs are automatically cleaned up.

appraisal_matrix:
  mode: semver
  gems:
    tier1:
      - name: mail

Produces ~5 entries like kja-mail-2-7-r2.4, kja-mail-2-8-r3.

appraisal_matrix:
  mode: semver
  gems:
    tier1:
      - name: activerecord
      - name: sequel
        mode: major
    tier2:
      - name: omniauth

Produces entries like kja-ar-7-1-oa-2-1-r3, kja-sq-5-0-oa-2-1-r3.

The resolve step also generates CI lifecycle groupings:

These map to separate GitHub Actions workflow files for tiered CI execution.

See SECURITY.md.

If you need some ideas of where to help, you could work on adding more code coverage, or if it is already 💯 (see below) check issues or PRs, or use the gem and think about how it could be better.

We so if you make changes, remember to update it.

See CONTRIBUTING.md for more detailed instructions.

See CONTRIBUTING.md.

Everyone interacting with this project's codebases, issue trackers, chat rooms and mailing lists agrees to follow the .

Made with contributors-img.

Also see GitLab Contributors: https://gitlab.com/appraisal-rb/kettle-jem-appraisals/-/graphs/main

⭐️ Star History

This library follows for its public API where practical. For most applications, prefer the Pessimistic Version Constraint with two digits of precision.

For example:

spec.add_dependency("kettle-jem-appraisals", "~> 0.0")

See CHANGELOG.md for a list of releases.

The gem is available under the following license: AGPL-3.0-only. See LICENSE.md for details.

If none of the available licenses suit your use case, please contact us to discuss a custom commercial license.

See LICENSE.md for the official copyright notice.

Maintainers have teeth and need to pay their dentists. After getting laid off in an RIF in March, and encountering difficulty finding a new one, I began spending most of my time building open source tools. I'm hoping to be able to pay for my kids' health insurance this month, so if you value the work I am doing, I need your support. Please consider sponsoring me or the project.

To join the community or get help, use the RubyForum or Discord.

To say "thanks!" ☝️ Join the community or 👇️ send money.

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Many parts of this project are actively managed by a kettle-jem smart template utilizing StructuredMerge.org merge contracts.

Thanks for RTFM. ☺️