uci-mcp/test/mcp.test.js

 'use strict'

 const expect = require('chai').expect,
   i2c = require('uci-i2c'),
   _u = require('uci-utils'),
   MCP = require('../lib/mcp23008-17')

 let bus1 = new i2c.Bus(1)

 const config_sets = {
   output: {
     dir: 0, // 0 output,1 input
     ivrt: 0,
     pullup: 0,
     intr: 0, // if intr = 0 usedef,deval not used
     usedef: 0, // if usedef = 0 defval not used
     defval: 0
   },
   toggle_switch: {
     dir: 1, // 0 output,1 input
     ivrt: 1, // for reading let 1 be zero and vice versa
     pullup: 1,
     intr: 1, // if intr = 0 usedef,deval not used
     usedef: 0, // if usedef = 0 defval not used
     defval: 0
   },
   momentary_switch: {
     dir: 1, // 0 output,1 input
     ivrt: 1, // for reading let 1 be zero and vice versa
     pullup: 1,
     intr: 1, // if intr = 0 usedef,deval not used
     usedef: 1, // if usedef = 0 defval not used
     defval: 1
   }
 }

 // console.log(bus1)
 // bus1.scan((devs)=>{console.log('devices: ', devs)})
 //bus1.scan().then(results=>console.log(results))

 describe('I2C Device Classes - ', function () {

   let mcp17 = new MCP.MCP23017(bus1, 0x20, {
     pin_cfg_default: 'momentary_switch',
     name: 'switches 1-16'
   })

   describe('MCP23017 Class - ', function () {

     it('can set and get a single pin config on both ports', function () {
       expect(mcp17.pin(1).cfg, "pin configs getter failed").to.deep.equal(config_sets.momentary_switch)
         //  expect(mcp17.pin(8).cfg.dir, "pin config getter failed").to.equal(0)
         //  mcp17.pin(8).cfg.dir = 1
         //  expect(mcp17.pin(8).config.dir, "pin address setter failed").to.equal(1)
         //  expect(mcp17.pin(8, 'B').cfg.dir, "pin address getter port B failed").to.equal(0)
         //  mcp17.pin(8, 'B').cfg.dir = 1
         //  expect(mcp17.pin(8, 'B').config.dir, "pin address setter failed").to.equal(1)
     });

   });

   let mcp8 = new MCP.MCP23008(bus1, 0x21, {
     pin_cfg_default: 'toggle_switch',
     name: 'relay 1-8'
   })

   describe('MCP23008 Class - ', function () {

     it('can set and get a single pin config', function () {
       expect(mcp8.pin(1).cfg, "pin configs getter failed").to.deep.equal(config_sets.toggle_switch)
         //  expect(mcp8.pin(8).cfg.dir, "pin address getter failed").to.equal(1)
         //  expect(mcp8.pin(8).cfg.ivrt, "pin address getter failed").to.equal(1)
         //  expect(mcp8.pin(8).cfg.usedef, "pin address getter failed").to.equal(0)
         //  mcp8.pin(8).cfg.dir = 0
         //  expect(mcp8.pin(8).cfg.dir, "pin address setter failed").to.equal(0)
         //  expect(mcp8.pin(8).ivrt, "pin address getter failed").to.equal(1)
     });

     const ADDR = 0x21,
       DIR = 0x00,
       RW = 0x09,
       ALLPINS = 0x40,
       NOPINS = 0x00

     mcp8.write(DIR, 0x00).then(() =>
       mcp8.write(RW, ALLPINS).then(() =>
         mcp8.read(RW, ALLPINS).then((resp) => {
           console.log('relays on', resp)
         })
       )
     )

   });

 });