@n1k1t/unit-generator

Unit generator

Coverage based unit tests AI generator

Install

npm i -D @n1k1t/unit-generator

How it works?

The unit-generator wraps the Keploy CLI util to make generation easier and more convenient in NodeJS projects In general, it uses an AI model to generate a unit test that should reach a higher coverage rate than it actually has. While generation AI prompts will be generated by Keploy based on an actual coverage. Using the unit-generator you can choose several modules to work with by provided tools like pattern files searching or ignore files

First steps

1. Install Keploy
2. Get access to API key on the OpenAI platform
3. Allow access to model gpt-o4-mini
4. Make .env file in the root of project that contents:

UNIT_GENERATOR_TEST_COMMAND="npx jest"
UNIT_GENERATOR_API_KEY="...API_KEY"
UNIT_GENERATOR_MODEL="gpt-4o-mini"

5. Setup project with Jest

{
  // Cobertura reporter is required
  "coverageReporters": ["cobertura"],
  // Recommend
  "collectCoverageFrom": ["<rootDir>/src/**/*.ts"],
  // Recommend
  "passWithNoTests": true,
}

6. Install the @n1k1t/unit-generator
7. Run npx unit calculate command

$ npx unit calculate

┌─────────┬───────┬────────────────────────┐
│ (index) │ rate  │ updated                │
├─────────┼───────┼────────────────────────┤
│ 0       │ 0.689 │ '20.03.2025, 19:48:31' │
└─────────┴───────┴────────────────────────┘

8. Done!

API

General

$ npx unit -h

Usage: cli [options] [command]

It generates unit-tests by Jest coverage

Options:
  -h, --help                    display help for command

Commands:
  summary [options]             Returns an overall coverage in the project
  calculate                     Calculates a coverage of the whole project and returns summary
  analyze [options] [pattern]   Returns a table of low covered project files
  generate [options] [pattern]  Generates unit tests
  help [command]                display help for command

Command summary

$ npx unit summary -h

Usage: cli summary [options]

Returns an overall coverage in the project

Options:
  -f --format [table|number]  Output format (default: "table")
  -h, --help                  display help for command

Examples

$ npx unit summary

┌─────────┬───────┬────────────────────────┐
│ (index) │ rate  │ updated                │
├─────────┼───────┼────────────────────────┤
│ 0       │ 0.689 │ '20.03.2025, 19:48:31' │
└─────────┴───────┴────────────────────────┘

$ npx unit summary -f number

0.689

Command calculate

$ npx unit calculate -h

Usage: cli calculate [options]

Calculates a coverage of the whole project and returns summary

Options:
  -h, --help  display help for command

Examples

$ npx unit calculate

┌─────────┬───────┬────────────────────────┐
│ (index) │ rate  │ updated                │
├─────────┼───────┼────────────────────────┤
│ 0       │ 0.689 │ '20.03.2025, 20:11:16' │
└─────────┴───────┴────────────────────────┘

Command analyze

$ npx unit analyze -h

Usage: cli analyze [options] [pattern]

Returns a table of low covered project files

Options:
  -t, --target [value]  Desired coverage target of an each file (default: "0.8")
  -l --limit [value]    Files limit (default: "5")
  -a --all              Takes all paths provided by pattern (default: false)
  -h, --help            display help for command

Examples

$ npx unit analyze -l 3 src/utils

┌─────────┬────────────────────────────────────────────────────────┬───────┐
│ (index) │ file                                                   │ rate  │
├─────────┼────────────────────────────────────────────────────────┼───────┤
│ 0       │ 'src/utils/streams/text-transform.ts'                  │ 0.107 │
│ 1       │ 'src/utils/streams/sse.ts'                             │ 0.316 │
│ 2       │ 'src/utils/dto/validators/has-dates-diff.validator.ts' │ 0.421 │
└─────────┴────────────────────────────────────────────────────────┴───────┘

Command generate

$ npx unit generate -h

Usage: cli generate [options] [pattern]

Generates unit tests

Options:
  -t, --target [value]      Desired coverage target of an each file (default: "0.8")
  -m, --model [value]       AI model to use for unit tests generation (default: "gpt-4o-mini")
  -i, --iterations [value]  Iterations maximum of unit tests generation (default: "5")
  -l --limit [value]        Files limit (default: "5")
  -v --verbose              Replaces pretty table with a raw Keploy as output (default: false)
  -a --all                  Takes all paths provided by pattern (default: false)
  -h, --help                display help for command

Examples

$ npx unit generate src/utils/dto/validators

┌─────────┬────────────────────────────────────────────────────────────────┬───────┬────────┬────────┬─────────┐
│ (index) │ file                                                           │ rate  │ target │ status │ spent   │
├─────────┼────────────────────────────────────────────────────────────────┼───────┼────────┼────────┼─────────┤
│ 0       │ 'src/utils/dto/validators/has-dates-diff.validator.ts'         │ 1     │ 0.8    │ 'DONE' │ 166.256 │
│ 1       │ 'src/utils/dto/validators/has-pattern-properties.validator.ts' │ 1     │ 0.8    │ 'DONE' │ 154.54  │
│ 2       │ 'src/utils/dto/validators/has-valid-timestamp.ts'              │ 0.636 │ 0.8    │ 'DONE' │ 137.068 │
└─────────┴────────────────────────────────────────────────────────────────┴───────┴────────┴────────┴─────────┘

Additional

ENV

# Desired coverage target of an each file
export UNIT_GENERATOR_COVERAGE_TARGET = "0.8"
# Path to the cobertura-coverage.xml file generated
export UNIT_GENERATOR_COBERTURA_PATH="coverage/cobertura-coverage.xml"
# Iterations maximum of unit tests generation
export UNIT_GENERATOR_MAX_ITERATIONS="5"
# Command that will be used to generate unit tests
export UNIT_GENERATOR_TEST_COMMAND="npm test"
# AI platform key
export UNIT_GENERATOR_API_KEY="..."
# AI model to use for unit tests generation
export UNIT_GENERATOR_MODEL="gpt-4o-mini"

Ignore file

The unit-generator package supports .unitignore file that can contain path matches using minimatch expressions

Examples

src/**/*.module.ts
src/**/index.ts
lib/**