How to use the expect.js.eql function in expect

test(`does not throw error and generates same tree[${f}]`, () => {
        let passSrc = fs.readFileSync(passTestFile, 'utf8');
        let passTree, passLocations, passComments;
        expect(() => {
          ({ tree: passTree, locations: passLocations, comments: passComments } = parse(passSrc, isModule(f), true));
        }).to.not.throwError();
        locationSanityCheck(passTree, passLocations);

        let passExplicitSrc = fs.readFileSync(passExplicitTestFile, 'utf8');
        let passExplicitTree;
        expect(() => {
          passExplicitTree = parse(passExplicitSrc, isModule(f), true).tree;
        }).to.not.throwError();

        expect.eql(passTree, passExplicitTree);

        let treeExpectation = JSON.parse(fs.readFileSync(expectationsDir + '/' + f + '-tree.json', 'utf8'));
        expect(decorateWithLocations(passTree, passLocations)).to.eql(treeExpectation);

        let commentExpectation = JSON.parse(fs.readFileSync(expectationsDir + '/' + f + '-comments.json', 'utf8'));
        expect(passComments).to.eql(commentExpectation);
      });
    }

ao.typeEqual = function(list){
  if(typeof list == 'string') list = list.split(',')
  var types = this.obj.map(function(item){
    return item.type
  });
  this.assert(
      expect.eql(types, list) 
    , function(){ return 'expected ' + list + ' to equal ' + types }
    , function(){ return 'expected ' + list + ' to not equal ' + types });
  return this;
}

function parseModule(name) {
    let source = require('fs').readFileSync(require.resolve(name), 'utf-8');
    let tree = ShiftParser.parseModule(source, { earlyErrors: true });
    let tree2 = ShiftParser.parseModule(source, { earlyErrors: false });
    expect.eql(tree, tree2);
  }

function parseScript(name) {
    let source = require('fs').readFileSync(require.resolve(name), 'utf-8');
    let tree = ShiftParser.parseScript(source, { earlyErrors: true });
    let tree2 = ShiftParser.parseScript(source, { earlyErrors: false });
    expect.eql(tree, tree2);
  }