Date-based e2e tests fail in Asia/Krasnoyarsk timezone

@sjbarag I've fixed tests and refactored code based on suggestions you've provided, I hope that everything is okay now.

FYI, I'm getting some weird issues when running tests locally:

Summary of all failing tests
 FAIL  test/brsTypes/components/RoDateTime.test.js
  ● RoDateTime › methods › getLastDayOfMonth › returns the date/time value's last day of the month

    expect(received).toEqual(expected) // deep equality

    - Expected  - 1
    + Received  + 1

      Int32 {
        "kind": 4,
    -   "value": 31,
    +   "value": 30,
      }

      210 |                 let result = getLastDayOfMonth.call(interpreter);
      211 |                 expect(getLastDayOfMonth).toBeTruthy();
    > 212 |                 expect(result).toEqual(new Int32(31));
          |                                ^
      213 |             });
      214 |         });
      215 |

      at Object.toEqual (test/brsTypes/components/RoDateTime.test.js:212:32)
      at processTicksAndRejections (node:internal/process/task_queues:93:5)

 FAIL  test/e2e/BrsComponents.test.js (5.228 s)
  ● end to end brightscript functions › components/roDateTime.brs

    expect(received).toEqual(expected) // deep equality

    - Expected  - 1
    + Received  + 1

    @@ -20,11 +20,11 @@
        "Minutes: ",
        "14",
        "Seconds: ",
        "15",
        "Last Day of Month: ",
    -   "30",
    +   "29",
        "Milliseconds: ",
        "160",
        "ISO String UTC: ",
        "2010-11-12T13:14:15Z",
      ]

      81 |         await execute([resourceFile("components", "roDateTime.brs")], outputStreams);
      82 |
    > 83 |         expect(allArgs(outputStreams.stdout.write).filter((arg) => arg !== "\n")).toEqual([
         |                                                                                   ^
      84 |             "Full Date: ",
      85 |             "Friday November 12, 2010",
      86 |             "No Week Day: ",

      at Object.toEqual (test/e2e/BrsComponents.test.js:83:83)

These two tests are failing when I run the yarn test locally, but seems to be passing in CI 🤔

Those are both date/time-based issues! Github reports your location as Serbia, so I wouldn't be surprised if our tests are a little flaky — most contributors are in UTC-7 / UTC-4, and the GitHub Actions runners probably use UTC as their timezone.

In fact, I'm able to reproduce that failure by running tests withTZ=Asia/Krasnoyarsk yarn test! You may want to run those tests locally with TZ=UTC yarn test, but I'll file an issue to figure out why those are failing with TZ=Asia/Krasnoyarsk. Sorry about that!

Originally posted by @sjbarag in https://github.com/sjbarag/brs/issues/598#issuecomment-764792408

sjbarag / brs

Date-based e2e tests fail in Asia/Krasnoyarsk timezone #612