A CLI tool to check type coverage for typescript code

This tool will check type of all identifiers, the type coverage rate = the count of identifiers whose type is not any / the total count of identifiers, the higher, the better.

yarn global add type-coverage

run type-coverage

If the identifiers' type arguments exist and contain at least one any, like any[], ReadonlyArray<any>, Promise<any>, Foo<number, any>, it will be considered as any too

Also, future minor release may introduce stricter type check in this mode, which may lower the type coverage rate

save and reuse type check result of files that is unchanged and independent of changed files in .type-coverage directory, to improve speed

If you want to get 100% type coverage then try {} catch {} is the largest blocked towards that.

This can be fixed in typescript with Allow type annotation on catch clause variable but until then you can turn on --ignore-catch --at-least 100.

Your catch blocks should look like

try {
  await ...
} catch (anyErr) {
  const err = <Error> anyErr
}

To have the highest type coverage.

This tool will ignore the files, eg: --ignore-files "demo1/*.ts" --ignore-files "demo2/foo.ts"

  "typeCoverage": {
    "atLeast": 99 // same as --at-least
  },

Use type-coverage:ignore-next-line or type-coverage:ignore-line in comment(// or /* */) to ignore any in a line.

try {
  // type-coverage:ignore-next-line
} catch (error) { // type-coverage:ignore-line
}

Use your own project url:

[![type-coverage](https://img.shields.io/badge/dynamic/json.svg?label=type-coverage&prefix=%E2%89%A5&suffix=%&query=$.typeCoverage.atLeast&uri=https%3A%2F%2Fraw.githubusercontent.com%2Fplantain-00%2Ftype-coverage%2Fmaster%2Fpackage.json)](https://github.com/plantain-00/type-coverage)

Using codechecks you can integrate type-coverage with GitHub's Pull Requests. See type-coverage-watcher.

import { lint } from 'type-coverage-core'

const result = await lint('.', { strict: true })

export function lint(project: string, options?: Partial<LintOptions>): Promise<FileTypeCheckResult & { program: ts.Program }>

export interface LintOptions {
  debug: boolean,
  files?: string[],
  oldProgram?: ts.Program,
  strict: boolean,
  enableCache: boolean,
  ignoreCatch: boolean,
  ignoreFiles?: string | string[],
  fileCounts: boolean,
}

export interface FileTypeCheckResult {
  correctCount: number
  totalCount: number
  anys: FileAnyInfo[]
  fileCounts: {
    correctCount: number,
    totalCount: number,
  }[]
}

Q: Does this count JavaScript files?

Yes, This package calls Typescript API, Typescript can parse Javascript file(with allowJs), then this package can too.

1. Move typescript from dependencies to peerDependencies
2. Move API from package type-coverage to package type-coverage-core

// v1
import { lint } from 'type-coverage'
lint('.', false, false, undefined, undefined, true)

// v2
import { lint } from 'type-coverage-core'
lint('.', { strict: true })