selo-solid

A selo rule pack with SOLID-alike rules. Use with @guilhermesilveira/selo.

Rules

| Rule id | Type | Default unit | What it caps | |---|---|---|---| | srp/max-file-lines | threshold | lines | source lines per file | | srp/max-function-lines | threshold | lines/fn | source lines per function | | srp/max-params | threshold | params/fn | parameters per function | | srp/max-depth | threshold | depth/fn | max nesting depth per function | | srp/max-statements-per-function | threshold | stmts/fn | top-level statements per function | | srp/max-cyclomatic-complexity | threshold | CC/fn | McCabe cyclomatic complexity per function | | srp/max-class-methods | threshold | methods | MethodDefinition count per class | | isp/max-interface-members | threshold | members | TSPropertySignature + TSMethodSignature count per interface (and per TSTypeLiteral) | | ocp/no-type-discriminating-switch | count | dispatches | switch / if-else-if chains over a single discriminator (kind/type/__typename/tag) |

Each rule's seal message names the unit value and the next refactor — never the bare "too many X."

Install

npm install --save-dev @guilhermesilveira/selo selo-solid

Use

In selo.config.mjs:

import solid from 'selo-solid';

export default {
  packs: [solid],
  rules: {
    'srp/max-file-lines':              { goal: 800 },
    'srp/max-function-lines':          { goal: 80 },
    'srp/max-params':                  { goal: 4 },
    'srp/max-depth':                   { goal: 4 },
    'srp/max-statements-per-function': { goal: 30 },
    'srp/max-cyclomatic-complexity':   { goal: 15 },
    'srp/max-class-methods':           { goal: 10 },
    'isp/max-interface-members':       { goal: 10 },
    'ocp/no-type-discriminating-switch': {},
  },
};

Then npx selo check (see the selo README for the full workflow).

OCP exemptions

The OCP rule sometimes fires on legacy code you can't refactor immediately. Exempt those files at the project level:

'ocp/no-type-discriminating-switch': {
  exempt: ['lib/legacy-dispatcher.ts', 'ui/old/Page.tsx'],
},

Paths are project-relative. The list is meant to be temporary — refactor and remove.

Layout

src/
  index.ts                     pack export (default + named rule exports)
  lib/walk.ts                  AST walker, function-name lookup, FN_TYPES
  rules/srpMaxFileLines.ts
  rules/srpMaxFunctionLines.ts
  rules/srpMaxParams.ts
  rules/srpMaxDepth.ts
  rules/srpMaxStatementsPerFunction.ts
  rules/srpMaxCyclomaticComplexity.ts
  rules/srpMaxClassMethods.ts
  rules/ispMaxInterfaceMembers.ts
  rules/ocpNoTypeDiscriminatingSwitch.ts
tests/
  helpers.ts                   fixtureFile() — parse + set parents
  *.test.ts                    one focused test per rule

Adding a rule

1. New file under src/rules/ exporting a SeloRule object. Use walkAst/walkAstSkip from lib/walk.js. Skip descent at nested function nodes if the measurement is per-function.
2. Add to src/index.ts's rules map under its meta.id.
3. Test under tests/<name>.test.ts using fixtureFile() to build a SeloFile.

Releasing

Manual SemVer release flow. See @guilhermesilveira/selo's release notes for the engine-releases-first ordering — when @guilhermesilveira/selo's contract changes, the engine ships first, then this pack bumps its peer range and follows.

# 1. Move [Unreleased] in CHANGELOG.md under a new
#    `## [<version>] — YYYY-MM-DD` heading.
# 2. If the engine bumped, update peerDependencies."@guilhermesilveira/selo"
#    in package.json.
# 3. npm version patch        # 0.0.1 → 0.0.2 (or `minor` / `major`)
# 4. git push --follow-tags
# 5. npm publish               # one-time `npm login` first

The prepublishOnly script gates publishing on a clean build + tests + lint, so a broken state can't ship.

What is not in this pack

• srp/no-identical-functions and srp/max-cognitive-complexity rely on SonarJS's algorithms. They live in selo-eslint-raiz (the shim pack) where the wrapping mechanism handles them.