Pimm / bancheck

Anti-TDD test runner that trusts you

bancheck

Conventional testing frameworks depend on you for the actual and the expected. Put differently: you have to write test code and predict the outcome. bancheck expects your code to work, and because it does it only depends on you for the actual.

That's your responsibilities cut in half right there. Writing tests becomes easier, as does maintaining tests.

An example

Say you have a function splitName which takes a human-inputted name and splits it into its different parts.

These are two tests:

const {test, expect} = require('bancheck');

test({
	pimm: splitName('Pimm Hogeling'),
	vincent: splitName('Vincent van Gogh')
})

This is the output:

{
	"passes": {
		"pimm": "Object {\
			\"familyName\": \"Hogeling\",\
			\"givenName\": \"Pimm\",\
		}",
		"vincent": "Object {\
			\"familyName\": \"van Gogh\",\
			\"givenName\": \"Vincent\",\
		}"
	},
	"fails": {}
}

Just double-check those passes and you are set.

Updating the tests

Now say later you come to your senses and realise the "van" in "Vincent van Gogh" is actually not part of his family name, but rather a tussenvoegsel.

Simply change splitName and re-run the test. This is the output:

{
	"passes": {
		"pimm": "Object {\
			\"familyName\": \"Hogeling\",\
			\"givenName\": \"Pimm\",\
		}"
	},
	"fails": {
		"vincent": {
			"expected": "Object {\
				\"familyName\": \"van Gogh\",\
				\"givenName\": \"Vincent\",\
			}",
			"actual": "Object {\
				\"familyName\": \"Gogh\",\
				\"givenName\": \"Vincent\",\
				\"tussenvoegsels\": \"van\",\
			}",
			"diff": …
		}
	}
}

One test fails, but not because your function is broken. The test is outdated. Update it by calling expect instead of test:

const {test, expect} = require('bancheck');

expect({
	pimm: splitName('Pimm Hogeling'),
	vincent: splitName('Vincent van Gogh')
})

This is the output:

{
	"passes": {
		"pimm": "Object {\
			\"familyName\": \"Hogeling\",\
			\"givenName\": \"Pimm\",\
		}",
		"vincent": "Object {\
			\"familyName\": \"Gogh\",\
			\"givenName\": \"Vincent\",\
			\"tussenvoegsel\": \"van\",\
		}"
	},
	"fails": {}
}

The tests have been updated, and you can call test again from this point on.

Usage

bancheck exports a test and an expect function. You can include test runs in your build script. If you are looking for a ready-to-go command-line interface, check out jest-cli.

bancheck saves the expected data in a snapshot file located at bancheck/snapshots.snap. You probably want to distribute that file along with your source code.