Enhance elementArrayFinder API

[donaldpipowitch]

elementArrayFinder already supports .map() which is quite nice, but I would also like to use other functions like .reduce() or .filter() which are typically supported by Array-like objects.

Example

Lets take the example from #392, but this time I don't want to know all menu labels, but look if one specific label appears once.

Menu
  one
  two
  three

Instead of writing this:

element.all(by.css('.menu .item')).map(function(item) {
  return item.getText();
}).then(function(labels) {
  return labels.filter(function(label) {
    return label === 'two ';
  });
}).then(function(labels) {
  expect(labels.length).toBe(1);
});

I could write this:

var items = element.all(by.css('.menu .item')).filter(function(item) {
  return item.getText().then(function(label) {
    return label === 'two ';
  });
});
expect(items.count()).toBe(1);

Or take this StackOverflow question.

Instead of writing this:

var total = 100;
var sum = element.all(By.repeater('item in publishers_data')).map(function(row) {
  return row.getText();
}).then(function(arr) {
  return arr.reduce(function(a, b) {
    return Number(a) + Number(b);
  })
});
expect(sum).toEqual(total);

We could write this:

var total = 100;
var sum = element.all(By.repeater('item in publishers_data')).reduce(function(rowA, rowB) {
  // lets imagine a `plus` function, which accepts promises for readability
  // and also returns a promise
  return plus(rowA.getText(), rowB.getText());
});
expect(sum).toEqual(total);

[hankduan]

merged with c892c2a

[donaldpipowitch]

Nice!