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Tool for testing using baseline strategy.

WARNING: it's early beta, so documentation may have mistakes, if you face any problems feel free to create issues.

Table of Contents

What is it?

This tool much like Jest or Mocha gives you an opportunity to test your application by creating unit-tests, it also supports end-to-end testing (actually WILL support).

But unlike other most known frameworks it uses another approach which could be named Baseline Strategy. Initially inspired by TypeScript tests (see them here) it looks like thing that's able to change way we're testing.


Current situation with TDD and tooling around it is complicated. There are a lot of problems and corner cases. And while everybody agrees that unit-testing is generally correct approach, amount of efforts required by it frequently makes TDD unsuitable for particular project.

We are trying to change it.

Our goal is moving TDD from processes (like agile, scrum, waterfall, etc.) to developer's tooling (like linters, compilers, etc.). In order to achieve it we have to focus on real strengths of TDD and unit-testing:

  1. Preventing unintentional breaking changes, in other words freezing existing behavior as some sort of 'baseline';
  2. Using documentation samples as tests and using tests as documentation.

To understand core idea and approach better, you can read Is TDD wrong? (RU)

How it works?

Let's assume you have module yourModule.js that exports one function. Baseline test (e.g. yourModule.spec.js) will look like this:

const yourModule = require('yourModule');

const oneUsage = yourModule('arguments', 'of', 'your', 'function');
const severalUsages = ['array', 'of', 'arguments'].map(yourModule);
let resultOfComplexUsageScenario;
// some code/function/promise that fulfils
// `resultOfComplexUsageScenario` with (a)sync value(s)

// actually any code that uses `yourModule` could be here

module.exports = {
    // any number of additional values


baset test

And this test will produce file yourModule.spec.tmp.base. It's temporary unverified baseline and contains all exported values (e.g. oneUsage, severalUsages, etc.). Just take a look at them and if you think they are correct run:

baset accept

And yourModule.spec.base will be generated. From this point you have test and baseline for yourModule that describe its behavior. All further test runs will compare generated yourModule.spec.tmp.base with yourModule.spec.base and fail if they are different, or pass otherwise.

Why I have to use it?

You haven't, but if you:

  • love TDD
  • hate TDD
  • don't care about it, but want to cover your application with tests
  • want to test everything
  • want to test only improtant cases
  • tired from describe, it, equalsTo that blows your tests and forces you to write a lot of code to test helloWorld.js
  • heard that tests are nearly the best type of documentation
  • never heard previous statement
  • disagree with it, because specs are unreadable in majority of cases
  • want it to be true for your project
  • feel lack of real usage examples in your project even though it has 100% coverage
  • feel lack of automated testing even though your documentation is full of examples

It worth trying baset.


For global, just run:

npm install -g baset

But we're recomending:

npm install --save-dev baset

and adding next lines to scripts section in your package.json:

"test": "baset",
"accept": "baset accept"


From command line:

baset <command> [options]


Name Description Aliases
test Default. Creating temp baseline and comparing it to existing one t
accept Accepting new baseline a
scaffold Scaffolding specs for existing code s


Option Description Type Default value
‑‑version Show version number boolean
‑‑specs, ‑s Glob pattern for spec files string "**/*.spec.js"
‑‑bases, ‑b Glob pattern for baseline files string "**/*.base"
‑‑help, ‑h Show help boolean
‑‑reporter, ‑r TAP reporter for test results. false to get plain TAP output string "tap-diff"
‑‑plugins, ‑p Plugins used for your tests string | configuration ".spec.js$:baset-baseliner-json"
‑‑options, ‑o Options for plugins TBD {}
‑‑files, ‑f Glob pattern for project files. Used by scaffolder. string undefined
‑‑isolateContext Run each test in isolated context. May be usefull, if your tests/code may affect other tests by mutating globals. ATTENTION: this will slow down your tests. boolean false

isolateContext In your package.json:

    "scripts": {
        "test": "baset",
        "accept": "baset accept"
    "baset": {
        "specs": "**/*.spec.js",
        "bases": "**/*.base",
        "plugins": {
            ".spec.js$": ["baset-plugin-module-name", "baset-baseliner-json"]
        "options": {
            "baset-plugin-module-name": {
                // List of options for baset plugin.
                // All available should be listed at
                // plugins file.

In .basetrc or .basetrc.json:

    "specs": "**/*.spec.js",
    "bases": "**/*.base",
    "plugins": {
        ".spec.js$": ["baset-plugin-module-name", "baset-baseliner-json"]
    "options": {
        "baset-plugin-module-name": {
            // List of options for baset plugin.
            // All available should be listed at
            // plugins file.

Plugins configuration

The most important configuration option is plugins. You may configure it via command line or via configuration file or even using baset section in package.json.

Using configuration file (same for package.json)

    "plugins": {
        "${pattern}": "${options}"

${pattern} - is regular expression for filename of your test files, so you may define different plugin options for different file types (e.g. using baset-reader-ts for .ts files and baset-reader-babel for .js files). ${options} - is string or string[] or object with following fields:

Field Description Type Default value
baseliner name or path to module, that is responsible for generating baseline string Required baset-baseliner-json
environment name or path to module, that mimics desired environment (e.g. browser) string undefined
readers name or path to module(s), that reads and transpiles specs and source code (e.g. babel, typescript) string[] | string undefined
resolvers name or path to module(s), that is able to resolve specific values (e.g. react components or pixi sprites) string[] | string undefined
imports name or path to module(s), that should be imported in test context (e.g. polyfills or reflect-metadata) string[] | string undefined
isolateContext Run each test in isolated context. May be usefull, if your tests/code may affect other tests by mutating globals. ATTENTION: this will slow down your tests. boolean false

If ${options} is string, then it used as baseliner name or path. If ${options} is string[], then it has to follow next agreement for its content:

["-env-pluginOrPath", ..."importPaths", ..."-reader-pluginsOrPaths",  ..."-resolver-pluginsOrPaths", "-baseliner-pluginOrPath"]

Where everything except baseliner is optional and ... means that several entities are allowed.

NOTE: grouping of entities is based on their names, so all plugins MUST contain substring -(env|reader|resolver|baseliner)-, except imports (last ones don't have any naming requirements).

Using CLI

Just type following command in your favorite terminal:

baset -p ${pattern}:${options}

${pattern} - is regular expression for filename of your test files (same as in previous paragraph). ${options} - is string[], where values are separated by : sign. This array has exactly same semantic as using string[] in configuration file.


Our tests folder contains projects used for end-to-end tests of baset package (using baset itself, of course), so you can use them as references for integrating baset into your workflow.


There are only few plugins right now:

  1. baset-baseliner-json - default plugin that used for creating baseline from exported values of spec
  2. baset-baseliner-md - plugin that used for creating baselines in Markdown format
  3. baset-env-browser - simple plugin that enables browser API in specs and sources using jsdom package.
  4. baset-reader-ts - simple plugin that allows to write specs using TypeScript
  5. baset-reader-babel - simple plugin that allows to write specs using Babel
  6. baset-reader-md - simple plugin that allows to write specs using MarkDown where only code blocks are executed, and # headings used for tests structuring.
  7. baset-resolver-react - simple plugin that resolves react components as html
  8. baset-resolver-pixi - simple plugin that resolver pixi DisplayObject as base64 encoded image


You may track progress for first stable release at this milestone


Recent changes can be viewed on the CHANGELOG

How to Contribute

Read to contribute CONTRIBUTING or

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How to Make Pull Request

Read to contribute PULL REQUEST TEMPLATE


Copyright (c) Ihor Chulinda. This source code is licensed under the MIT license.