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Function: testMonadLaws()

testMonadLaws<M, A>(config): void

Defined in: testing/laws/monad.ts:66

Test that a monad implementation satisfies monad laws.

This function generates test suites that verify:

  • Left Identity: flatMap(of(a), f) === f(a)
  • Right Identity: flatMap(ma, of) === ma
  • Associativity: flatMap(flatMap(ma, f), g) === flatMap(ma, x => flatMap(f(x), g))

Type Parameters​

M​

M

A​

A

Parameters​

config​

MonadLawConfig<M, A>

Configuration specifying the monad and test cases

Returns​

void

Example​

import { testMonadLaws } from 'receta-test/laws'
import { ok, err } from 'receta/result'
import * as Result from 'receta/result'

describe('Result', () => {
  testMonadLaws({
    type: 'Result',
    of: ok,
    flatMap: Result.flatMap,
    testCases: [
      {
        value: 5,
        functions: [
          (x: number) => ok(x * 2),
          (x: number) => x > 0 ? ok(x) : err('negative')
        ]
      }
    ]
  })
})