How to convert a promise in protractor to a float

Question

I'm writing e2e tests using protractor and I'd like to check if some values on the page are correctly calculated. Something very simple like this:

var var1 = element(by.binding('var1'));
var var2 = element(by.binding('var2'));
var var3 = element(by.binding('var3'));

expect(parseFloat(var1.getText())).toEqual(parseFloat(var2.getText()) + 
       parseFloat(var2.getText()));

However, because var1, var2 and var3 are all promises, this does not work.

Is there a way of converting the promise object to strings so that I can make the above work?

Answer 1

Since promises are asynchronous, you can't convert them to a float with a synchronous function. So, you'll need to resolve them. You could do this like:

element(by.binding('var1').getText().then(function(text1) {
  element(by.binding('var2').getText().then(function (text2) {
    element(by.binding('var3').getText().then(function (text3) {
      expect(parseFloat(text1)).toEqual(parseFloat(text2) + parseFloat(text3));
    });
  });
});

Answer 2

I write my tests with the following pattern:

var data = {};
element(by.binding('var1')).getText().then(function(value) { data.var1text = value; });
element(by.binding('var2')).getText().then(function(value) { data.var2text = value; });
element(by.binding('var3')).getText().then(function(value) { data.var3text = value; });
expect(parseFloat(data.var1text)).toEqual(parseFloat(data.var2text) + parseFloat(data.var3text));

The pattern is rather short and clear, and all the values from the promises are available for further analysis.