import assert from 'assert'
import poortf from '../poortf.js'

describe('poortf', () => {
   const slate = poortf('slate')
   it('creates an empty tf', () => {
      assert.throws(() => slate('empty'), TypeError)
      assert.throws(() => slate('empty'), /slate.*empty/)
   })

   const add = poortf('add', [
      [args => Array.from(args).every(a => typeof a === 'number'),
       (a, b) => a+b],
      [args => Array.from(args).every(a => typeof a === 'boolean'),
       (p, q) => p || q]
   ])
   
   it('creates a tf with initial behaviors', () => {
      assert.strictEqual(add(2,2), 4)
      assert.strictEqual(add(true, false), true)
      assert.throws(() => add('kilroy'), TypeError)
   })

   const defNumber = what => {
      slate.addImps([args => typeof args[0] === 'number',
                     n => 'I am not number ' + (what+n)],
                    defNumber, what+1)
   }
   
   it('extends an empty tf', () => {
      defNumber(2)
      assert.strictEqual(slate(0, 'was here'), 'I am not number 2')
      assert.throws(() => slate('Kilroy', 'was here'), TypeError)
      slate.addImps([
         [args => typeof args[0] === 'string', s => s + ' wuz here'],
         [args => typeof args[0] === 'boolean', () => 'Maybe I am a number']
      ])
      assert.strictEqual(slate('Kilroy', 'was here'), 'Kilroy wuz here')
      assert.strictEqual(slate(true), 'Maybe I am a number')
      assert.throws(() => slate(['Ha!']), TypeError)
   })

   it('extends a tf with other behaviors', () => {
      add.addImps([args => typeof args[0] === 'string', (s,x) => s + x]),
      assert.strictEqual(add('Kilroy', 23), 'Kilroy23')
      assert.throws(() => add(['Ha!'], 'gotcha'), TypeError)
   })
   
   it('can invalidate and lazily reload implementations', () => {
      slate.invalidate(defNumber)
      assert.strictEqual(slate.imps.length, 3) // reloader plus two non-number
      assert.strictEqual(slate(1), 'I am not number 4') // 'what' is now 3!!
      assert.strictEqual(slate('Yorlik', 7), 'Yorlik wuz here')
      assert.strictEqual(slate(false), 'Maybe I am a number')
      assert.strictEqual(slate.imps.length, 3) // reloader gone
   })
})