Load multiple mocks for a single call

[jtasse]

Background

I'll start by saying that this may be (hopefully) just my misunderstanding of how the mocks work.

In any case, I wrote a GAS method named getSummaryHTML() that calls getActiveSpreadsheet() (from SpreadsheetApp) and getSheetByName() (from the current spreadsheet), among other things.

Desired behavior:

I would like to be able to mock each of these calls and provide a return value for a single (test) call to the parent function.

Problem

TLDR; There does not appear to be a way to mock more than one dependency for a single function call/test.

As I understand it, the gas-local require method takes a single globalObject, which can be defined in a test like this:

var actualMock = {
            SpreadsheetApp: { getActiveSpreadsheet: function () { return 'TestSpreadSheetName'; } },
            __proto__: defMock
        },

This will successfully mock the behavior of getActiveSpreadSheet and return 'TestSpreadSheetName'.

However, if I wanted to mock the behavior for both getSummaryHTML() and getActiveSpreadsheet() within a single test for a single method, there doesn't appear to be a way to facilitate this. For example, this doesn't work, as the require function is not set up to handle an array:

var actualMocks = [
        {
            SpreadsheetApp: { getActiveSpreadsheet: function () { return 'TestSpreadSheetName'; } },
            __proto__: defMock
        },
        {
            SpreadsheetApp: { getSheetByName: function () { return 'TestSheetName'; } },
            __proto__: defMock
        }
    ];

Possible Solution

I did look into possible adding a multiplerequire function to bundle the mocks together in a single object, but I don't know enough about how Context objects work at the moment (e.g. - I could call require multiple times, but I believe that would just run the test once for each mock object, which is not what I want).

[andodet]

I am facing the exact same problem: in my case a method relies on couple functions from UrlFetchApp but I have successfully managed to mock just one of the two.

/**
 * API call to fetch the time in Rome
 * @returns {string} A date string with format `%Y-%m-%d`
 * @customfunction
*/
function FETCHTIME() {
  const res = UrlFetchApp.fetch('http://worldtimeapi.org/api/timezone/Europe/Rome');
  let time = JSON.parse(res.getContentText());

  // Get date from timestamp
  time = time.datetime.slice(0, 10);
  return time;
}

And here's my test where I want to check the function actually returns the right date:

const { assert } = require('chai');
const gas = require('gas-local');

const defMock = gas.globalMockDefault;
const customMock = {
  UrlFetchApp: {
    fetch: function () { return 'HTTPResponse'; },
    getContentText: function () { return 'verylongstring'; },
    __proto__: defMock
  }
};

// Import function in custom module
var glib = gas.require('./src', customMock);

describe('fetch_time', function () {
  describe('#FETCHTIME', function () {
    it('should return a "%Y-%m-%d" string', function () {
      assert.equal(glib.FETCHTIME(), '2020-09-07')
    })
  })
})

The test fails with a TypeError: res.getContentText is not a function.

[andodet]

Right, with a bit more research I've stumbled onto this repo which has a great example of how to use custom mocks.

The gist is to have a test/mocks folder and define mocks for single services in there, once you mocked everything you need you can import them in your test (example here.

edit: I agree with #12, being many ways to set things up I believe that a guide on how to move the first steps would be very helpful to get people productive faster. Could be easily written using Github wikis