🍲 Kettle::Jem::Appraisals

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👣 How will this project approach the September 2025 hostile takeover of RubyGems? 🚑️

I've summarized my thoughts in this blog post.

🌻 Synopsis

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).

Key concepts

Concept	Description
Tier 1	Primary runtime dependencies whose version matrix you test against (e.g. `activerecord`, `mail`)
Tier 2	Secondary runtime dependencies cross-producted with tier 1 (e.g. `omniauth`)
Ruby series	Buckets like `r2.4`, `r2.6`, `r2`, `r3.1`, `r3` derived from min-ruby seam analysis
Seam	A version boundary where a gem's `required_ruby_version` floor increases
Mode	Version selection strategy: `major`, `minor`, `patch`, `minor-minmax`, or `semver`
`kja-` prefix	All generated appraisal names start with `kja-` for reliable cleanup on regeneration

💡 Info you can shake a stick at

Tokens to Remember
Works with JRuby
Works with MRI Ruby 4
Support & Community
Source
Documentation
Compliance
Style
Maintainer 🎖️
`...` 💖	🧊 🐙 🛖 🧪

Compatibility

Compatible with MRI Ruby 4.0.0+, and JRuby. CI workflows and Appraisals are generated for MRI Ruby 4.0.0+. This test floor is configured by ruby.test_minimum in .structuredmerge/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
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

Federated DVCS

Find this repo on federated forges (Coming soon!)

Federated DVCS Repository	Status	Issues	PRs	Wiki	CI
🧪 appraisal-rb/kettle-jem-appraisals on GitLab	The Truth	💚	💚	💚	🐭 Tiny Matrix
🧊 appraisal-rb/kettle-jem-appraisals on CodeBerg	An Ethical Mirror (Donate)	💚	💚	➖	⭕️ No Matrix
🐙 appraisal-rb/kettle-jem-appraisals on GitHub	Another Mirror	💚	💚	💚	💯 Full Matrix

Enterprise Support

Available as part of the Tidelift Subscription.

Need enterprise-level guarantees?

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💡Subscribe for support guarantees covering all your FLOSS dependencies
💡Tidelift is part of Sonar
💡Tidelift pays maintainers to maintain the software you depend on!
📊@Pointy Haired Boss: An enterprise support subscription is "never gonna let you down", and supports open source maintainers

Alternatively:

✨ Installation

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

Configuration lives under the appraisal_matrix key of the project's kettle-jem configuration file, .structuredmerge/kettle-jem.yml — the same file kettle-jem reads when templating. Projects that still have a legacy root .kettle-jem.yml (and no .structuredmerge/kettle-jem.yml) are read from there instead. Running --scaffold creates a starter appraisal_matrix from your gemspec.

Writes are surgical: --scaffold and --resolve only rewrite the top-level sections they change (normally just appraisal_matrix), so comments and every other kettle-jem setting in the file are preserved.

Config schema

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"

  # How generated entries collapse onto kettle-jem's standard ruby-X-Y
  # appraisals (default: unique). See "Collapsing onto standard appraisals".
  standard_appraisal_role: runtime_dependency

  # Shared support gemfiles evaluated by every generated entry (and injected
  # by kettle-jem into standard test appraisals). See "Shared support gemfiles".
  appraisal_gemfiles:
    - modular/combustion.gemfile

  # Generate and wire ActiveRecord database support gemfiles when activerecord
  # is a tier1 gem (default: true). See "ActiveRecord database support".
  activerecord_support: true

  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

Version selection modes

Mode	Selects	Best for
`major`	Latest minor of each major version	Large gems with many majors (e.g. Rails)
`minor`	Every minor version across all majors	Small gems with few versions
`patch`	Every matching patch version	Tight compatibility windows or regression-focused matrices
`minor-minmax`	First + last minor per older major; all minors of current major	Balanced coverage
`semver`	Latest minor per older major + Ruby-cutoff minors + all minors of current major unless that major is large, then latest + cutoffs	Default — best signal-to-noise ratio

Per-gem requirements

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.

Per-gem include_versions

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

Per-gem exclude_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

Semver pruning

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.

Appraisal naming

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:

Gem	Abbreviation
`activerecord`	`ar`
`activesupport`	`as`
`omniauth`	`oa`
`mongoid`	`mo`
`sequel`	`sq`

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

Collapsing onto standard appraisals

kettle-jem already generates one standard appraisal per supported Ruby series (ruby-2-7, ruby-3-1, …), and each of those already has a CI job. A generated kja-* entry whose Ruby bucket maps to one of those series would otherwise be a duplicate appraisal (and duplicate CI job) for the same Ruby. To avoid that, kettle-jem-appraisals intentionally collapses one generated entry per standard series onto the standard name: the entry keeps its kja-* name internally, but is emitted as appraise "ruby-X-Y". kettle-jem then merges that block with its own templated ruby-X-Y block, so the standard job runs against the generated dependency versions. Every entry that is not collapsed keeps its kja-* name, and stale-file cleanup still keys off the kja- prefix.

Which entry collapses is controlled by the collapse policy, read from appraisal_matrix.collapse.standard_appraisals, standard_appraisal_role, or standard_appraisal_collapse (first one set wins):

Policy	Accepted values	Behavior
unique (default)	anything not listed below	Collapse only when a single generated entry maps to the series; ambiguous series keep all entries as `kja-*`.
required	`required`, `runtime`, `runtime_dependency`, `dependency`, `substrate`	Always collapse one entry per series — the one with the highest tier1 (then tier2) version. Use when the tier1 gem is a runtime dependency every standard job needs.
none	`none`, `false`, `off`, `no`, `never`	Never collapse; every entry stays `kja-*`.

For example, with standard_appraisal_role: runtime_dependency and an activerecord tier1, the r3.1 bucket's ActiveRecord 7.2 entry is emitted as ruby-3-1, while an extra ActiveRecord 7.0 entry for the same bucket stays kja-ar-7-0-r2.

Shared support gemfiles

appraisal_matrix.appraisal_gemfiles (alias: appraisal_eval_gemfiles) lists modular gemfiles that every generated entry should eval_gemfile, such as test-only fixtures (modular/combustion.gemfile). Paths may be given with or without the leading gemfiles/. kettle-jem reads the same key (or workflows.standard_appraisal_gemfiles) to inject those gemfiles into its standard test appraisals, so collapsed and non-collapsed jobs share them.

kettle-jem's test_bundle.gemfiles is separate: it controls the root Gemfile used for local development and the locked-deps workflow, and is not changed by appraisal_matrix.

ActiveRecord database support

This gem's primary use case is gems that are tested against a spread of ActiveRecord versions on MRI, JRuby, and TruffleRuby. Those test suites need a database driver whose gem differs per engine and per ActiveRecord version: sqlite3 on MRI/TruffleRuby, activerecord-jdbcsqlite3-adapter (plus bigdecimal) on JRuby. When activerecord is a tier1 gem, --resolve:

writes gemfiles/modular/activerecord_support.gemfile (sqlite3 1.4.x, for ActiveRecord < 7.2) and gemfiles/modular/activerecord_support_modern.gemfile (sqlite3 >= 2.1, for ActiveRecord >= 7.2), each with a JRuby platform block for the JDBC adapter, whose release series tracks ActiveRecord so Bundler picks the matching adapter;
adds the matching support gemfile to each generated entry, based on that entry's ActiveRecord version (unless appraisal_gemfiles already lists one of them).

Existing support gemfiles that do not carry the # Generated by kettle-jem-appraisals header are treated as hand-maintained and left untouched. Set activerecord_support: false to opt out entirely (for example, when the suite uses PostgreSQL). Point the root Gemfile at the modern support gemfile via kettle-jem's test_bundle.gemfiles, and select the JDBC adapter in your spec helper on JRuby:

require "active_record"
if RUBY_PLATFORM == "java"
  require "activerecord-jdbcsqlite3-adapter"
else
  require "sqlite3"
end
adapter = (RUBY_PLATFORM == "java" && ActiveRecord.version < Gem::Version.new("7.2")) ? "jdbcsqlite3" : "sqlite3"
ActiveRecord::Base.establish_connection(adapter: adapter, database: ":memory:")

Optimal bucket assignment

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:

Version	Optimal bucket	Reason
AR 5.2	`r2.4`	Next seam (AR 6.0) needs Ruby ≥2.5; newest Ruby below is 2.4
AR 6.1	`r2.6`	Next seam (AR 7.0) needs Ruby ≥2.7; newest Ruby below is 2.6
AR 7.1	`r2`	Next seam (AR 7.2) needs Ruby ≥3.1; newest Ruby below is 2.7
AR 7.2	`r3.1`	Next seam (AR 8.0) needs Ruby ≥3.2; newest Ruby below is 3.1
AR 8.1	`r3`	Catch-all latest bucket

🔧 Basic Usage

Two-step workflow

Step 1 — Scaffold reads your gemspec and populates appraisal_matrix in .structuredmerge/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)

CLI flags

Flag	Description
`--scaffold`	Force scaffold mode (even if config exists)
`--resolve`	Force resolve mode
`--force`	Bypass freshness TTL and re-resolve

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

Re-resolving

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.

Example: sanitize_email (tier1-only)

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

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

Example: omniauth-identity (tier1 + tier2)

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.

Workflow strategy output

The resolve step also generates CI lifecycle groupings:

Lifecycle	Description
`supported`	Current Ruby series (actively maintained)
`legacy`	Older Ruby series (maintenance mode)
`unsupported`	Ruby versions past EOL
`ancient`	Very old Ruby (best-effort)

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

🔐 Security

See SECURITY.md.

🤝 Contributing

If you need some ideas of where to help, you could work on adding more code coverage, 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.

🚀 Release Instructions

See CONTRIBUTING.md.

Code Coverage

Coverage service badges

🪇 Code of Conduct

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

🌈 Contributors

Made with contributors-img.

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

📌 Versioning

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")

📌 Is "Platform Support" part of the public API? More details inside.

Dropping support for a platform can be a breaking change for affected users. If a release changes supported platforms, it should be called out clearly in the changelog and versioned with that impact in mind.

To get a better understanding of how SemVer is intended to work over a project's lifetime, read this article from the creator of SemVer:

"Major Version Numbers are Not Sacred"

See CHANGELOG.md for a list of releases.

📄 License

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.

© Copyright

See LICENSE.md for the official copyright notice.

🤑 A request for help

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.

💌 💌 💌

Please give the project a star ⭐ ♥.

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

Thanks for RTFM. ☺️

Field	Value
Package	kettle-jem-appraisals
Description	🍲 Kettle::Jem::Appraisals auto-generates CI test matrices from RubyGems API data. Scaffolds tier1/tier2 gem lists from gemspec, resolves version spreads per mode (major/minor/minor-minmax/semver), generates modular gemfiles and Appraisals files. Part of the kettle-dev ecosystem.
Homepage	https://github.com/appraisal-rb/kettle-jem-appraisals
Source	https://github.com/appraisal-rb/kettle-jem-appraisals
License	`AGPL-3.0-only`
Funding	https://github.com/sponsors/pboling, https://ko-fi.com/pboling, https://liberapay.com/pboling/donate, https://opencollective.com/kettle-dev, https://thanks.dev/u/gh/pboling, https://tidelift.com/funding/github/rubygems/kettle-jem-appraisals, https://www.buymeacoffee.com/pboling