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  • License Apache-2.0

Strict, opinionated ESLint rules for TypeScript — enforcing type safety, code quality, testing standards, and maintainable patterns with zero exceptions.

Package Exports

  • @coderrob/eslint-plugin-zero-tolerance

Readme

@coderrob/eslint-plugin-zero-tolerance

Strict, opinionated ESLint plugin for TypeScript that enforces type safety, code quality, testing standards, and maintainable patterns with zero exceptions.

npm version License

Features

  • 52 custom ESLint rules covering type safety, code quality, testing, imports, and bug prevention
  • recommended preset (enabled default rules at warn) and strict preset (enabled default rules at error)
  • ESLint 9 flat config and ESLint 8.x legacy config support
  • Built with @typescript-eslint/utils for TypeScript AST support

Requirements

  • Node.js

    • 17 when using ESLint 8.57.0+ or 9.x

    • 19 when using ESLint 10.x

  • ESLint 8.57.0+, 9.x, or 10.x
  • @typescript-eslint/parser 8.x
  • TypeScript 5.x

Installation

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

Quick Start

ESLint 9+ (Flat Config)

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

export default [zeroTolerance.configs.recommended];

ESLint 8.x (Legacy Config)

// .eslintrc.js
module.exports = {
  plugins: ['zero-tolerance'],
  extends: ['plugin:zero-tolerance/legacy-recommended'],
};

Custom Rule Selection

// 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 }],
    },
  },
];

Presets

Preset Severity Config Key
Recommended warn configs.recommended
Strict error configs.strict
Legacy Recommended warn legacy-recommended
Legacy Strict error legacy-strict

Rules

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

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-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 ordered by group and alphabetically within each group
sort-functions Require top-level functions and const function expressions 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

no-parent-internal-access remains opt-in and only matches the first concrete directory reached after .. traversal, such as ../src/foo.

Rule Description
require-clean-barrel Require barrel files (index.*) to contain only module re-exports
no-barrel-parent-imports Disallow parent-directory traversal in barrel-file import paths
no-parent-internal-access Disallow 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-exports from parent/grandparent modules

Bug Prevention

Rule Description
no-identical-expressions Disallow identical expressions on both sides of a binary or logical operator
no-identical-branches Disallow identical conditional branches
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

Documentation

Full rule documentation with examples is available at:

https://coderrob.github.io/eslint-config-zero-tolerance/

License

Apache 2.0 Copyright Robert Lindley