@coderrob/eslint-plugin-zero-tolerance

60 opinionated ESLint rules for TypeScript teams that refuse to compromise on code quality.

---

Zero tolerance means every rule earns its place. No warnings you learn to ignore. No exceptions you forget about. Every violation is a conversation about quality — and quality always wins.

Why Zero Tolerance?

Most linting setups start strict and erode over time. A scattered eslint-disable here, an any cast there, and before long the rules exist in name only.

This plugin takes the opposite approach:

• No eslint-disable comments — fix the root cause, don't silence the symptom.
• No any smuggling — type assertions and non-null assertions are flagged.
• No magic values — every number and string earns a name.
• No leaky tests — persistent mocks, imprecise matchers, and timer abuse are caught.
• No complexity hiding — functions stay short, parameters stay few, imports stay clean.

The result is a codebase where the rules are the culture and the culture is visible in every file.

---

Documentation

Hosted docs	https://coderrob.github.io/eslint-config-zero-tolerance/
Rules reference	docs/rules/index.md
Configuration guide	docs/configuration.md

Packages

This monorepo publishes two packages:

Package	Description
@coderrob/eslint-plugin-zero-tolerance	The ESLint plugin — 60 custom rules
@coderrob/eslint-config-zero-tolerance	Pre-built recommended and strict config presets

Requirements

• ESLint 8.57.0+, 9.x, or 10.x
• TypeScript-ESLint 8.x
• TypeScript 5.x

Installation

npm install --save-dev @coderrob/eslint-plugin-zero-tolerance @typescript-eslint/parser

Usage

ESLint 9+ (Flat Config)

Using the recommended preset:

// eslint.config.js
import zeroTolerance from '@coderrob/eslint-plugin-zero-tolerance';

export default [
  zeroTolerance.configs.recommended,
  // your other configs...
];

Using the strict preset:

// eslint.config.js
import zeroTolerance from '@coderrob/eslint-plugin-zero-tolerance';

export default [
  zeroTolerance.configs.strict,
  // your other configs...
];

Alternative: Import presets directly from the config package:

// eslint.config.js
import recommended from '@coderrob/eslint-config-zero-tolerance/recommended';
// or
import strict from '@coderrob/eslint-config-zero-tolerance/strict';

export default [
  recommended, // or strict
  // your other configs...
];

Custom configuration:

// eslint.config.js
import zeroTolerance from '@coderrob/eslint-plugin-zero-tolerance';

export default [
  {
    plugins: {
      'zero-tolerance': zeroTolerance,
    },
    rules: {
      'zero-tolerance/require-interface-prefix': 'error',
      'zero-tolerance/no-throw-literal': 'error',
      'zero-tolerance/max-function-lines': ['warn', { max: 40 }],
      // ... other rules
    },
  },
];

ESLint 8.x (Legacy Config)

Using .eslintrc.js:

module.exports = {
  plugins: ['zero-tolerance'],
  extends: ['plugin:zero-tolerance/legacy-recommended'],
  // or for strict mode:
  // extends: ['plugin:zero-tolerance/legacy-strict'],
};

Rules

All 60 rules are organized into eight categories. Nearly all are included in both the recommended (warn) and strict (error) presets. A handful are opt-in only — see the Configuration guide for the full preset table.

Naming Conventions

Rule	Description
require-interface-prefix	Enforce that TypeScript interface names start with I followed by an uppercase letter

Documentation

Rule	Description
require-bdd-spec	Enforce that every TypeScript source file has a valid sibling .ts.bdd.json BDD spec
require-jsdoc-anonymous-functions	Require JSDoc comments on anonymous function-like constructs except test files and known test callbacks
require-jsdoc-functions	Require JSDoc comments on named functions (except test files)
require-optional-chaining	Require optional chaining instead of repeated guard access
require-readonly-props	Require JSX component props to be typed as readonly

Testing

Rule	Description
require-test-description-style	Enforce that test descriptions start with should
no-jest-have-been-called	Prohibit imprecise call-assertion matchers; use toHaveBeenCalledTimes and toHaveBeenNthCalledWith instead
no-mock-implementation	Prohibit persistent mock methods; use Once variants to prevent test bleeds
no-set-timeout-in-tests	Disallow setTimeout usage in test files
no-set-interval-in-tests	Disallow setInterval usage in test files
no-fetch-in-tests	Disallow fetch usage in test files
no-restricted-imports-in-tests	Disallow configured dependency imports in test files
no-test-interface-declaration	Disallow interface declarations in test files; import production types instead

Type Safety

Rule	Description
no-type-assertion	Prevent use of TypeScript as and angle-bracket assertions
no-non-null-assertion	Disallow non-null assertions using the ! postfix operator
no-literal-unions	Ban literal union types in favour of enums
no-literal-property-unions	Require property literal unions to use named domain types
require-union-type-alias	Require inline union types with multiple type references to use named type aliases
no-banned-types	Ban ReturnType and indexed access types
no-inline-type-import	Disallow inline import("...").Type annotations
no-destructured-parameter-type-literal	Disallow inline object type literals on destructured parameters
require-exported-object-type	Require exported object constants to declare an explicit type annotation

Code Quality

Rule	Description
max-function-lines	Enforce a maximum number of lines per function body
max-params	Enforce a maximum number of function parameters
no-array-mutation	Disallow mutating array methods
no-date-now	Disallow Date.now() and no-arg new Date() usage
no-magic-numbers	Disallow magic numbers; use named constants instead
no-magic-strings	Disallow magic strings in comparisons and switch cases
no-object-mutation	Disallow direct object-property mutation
sort-imports	Require import declarations to be grouped and alphabetized
sort-functions	Require top-level functions to be sorted alphabetically
prefer-nullish-coalescing	Prefer nullish coalescing instead of repeated nullish guard ternaries
prefer-readonly-parameters	Prefer readonly typing for object and array-like parameters
prefer-string-raw	Prefer String.raw for strings containing escaped backslashes

Error Handling

Rule	Description
no-empty-catch	Disallow empty catch blocks that silently swallow errors
no-throw-literal	Disallow throwing literals, objects, or templates; always throw a new Error instance
prefer-result-return	Prefer returning Result-style values instead of throwing

Imports

Rule	Description
require-clean-barrel	Require barrel files (index.*) to contain only module re-exports
no-barrel-parent-imports	Ban .. and ../* parent-directory import traversal in barrel files
no-parent-internal-access	Ban parent-relative access into protected internal directories such as src
no-dynamic-import	Ban dynamic import() and require() outside test files
no-export-alias	Prevent use of aliases in export statements
no-re-export	Disallow direct or pass-through re-export statements from parent/grandparent modules
require-node-protocol	Require Node.js built-in module imports to use the node: protocol prefix

Bug Prevention

Rule	Description
no-identical-expressions	Disallow identical expressions on both sides of a binary or logical operator
no-identical-branches	Disallow identical branches in if/else and ternary conditionals
no-boolean-return-trap	Disallow ambiguous boolean-return APIs outside predicate naming
no-redundant-boolean	Disallow redundant comparisons to boolean literals
no-for-in	Disallow for..in loops
no-labels	Disallow labeled statements
no-with	Disallow with statements
no-await-in-loop	Disallow await inside loops; use Promise.all() instead
no-floating-promises	Disallow unhandled promise expressions; require explicit handling
no-eslint-disable	Prevent use of eslint-disable comments
no-parameter-reassign	Disallow reassigning function parameters
no-flag-argument	Disallow boolean flag parameters in function signatures
prefer-guard-clauses	Prefer guard clauses by removing else blocks after terminating if branches
prefer-shortcut-return	Prefer shortcut boolean returns over if branches that return true/false
no-query-side-effects	Disallow side effects in query-style functions

Development

This repository itself is a pnpm workspace and dogfoods its own rules through eslint.config.mjs. Every source file in the plugin must pass the same rules it enforces on consumers.

Setup

pnpm install

Building

pnpm build

Testing

pnpm test

Coverage gates are enforced per-file at 95% minimum across statements, branches, functions, and lines. The test command also refreshes the coverage badge automatically.

Type Checking

pnpm --filter @coderrob/eslint-plugin-zero-tolerance exec tsc -p tsconfig.json --noEmit
pnpm --filter @coderrob/eslint-config-zero-tolerance exec tsc -p tsconfig.json --noEmit

Dependency Graph

pnpm deps:graph
pnpm deps:circular

Publishing

This monorepo provides automated scripts to handle versioned releases.

Quick release (single command):

pnpm release:prepare --release patch --commit --tag --publish

This will:

• bump the root, plugin, and config package versions
• replace workspace:* with a versioned peer dependency in packages/config
• run pnpm build and pnpm test
• create a release commit and annotated git tag
• publish both packages to npm

If you want to restore workspace:* after publishing for local development, run:

pnpm release:restore-workspace

Or include --restore-workspace and commit that restoration separately.

Manual/stepwise release flow:

# 1. Build all packages
pnpm build

# 2. Run tests to ensure everything works
pnpm test

# 3. Prepare packages for publishing (converts workspace:* to versioned dependency)
pnpm release:prepare

# 4. Publish the plugin package
cd packages/plugin
npm publish

# 5. Publish the config package
cd ../config
npm publish

# 6. Restore workspace:* for local development
cd ../..
pnpm release:restore-workspace

Additional release:prepare options:

# Bump versions and prepare manifests without publishing
pnpm release:prepare --release minor

# Skip build/test if already run in CI or a previous step
pnpm release:prepare --release 1.2.0 --skip-build --skip-test --commit --tag --publish

# Dry run the full flow
pnpm release:prepare --release patch --commit --tag --publish --dry-run

License

Apache 2.0 Copyright Robert Lindley