Can't programmatically format with language.

And as is always the case, after spending 3 hours trying to get this to work, 2 min after posting this i figure it out:

    if ($langcode == 'fr') {
      $language_manager = \Drupal::service('language_manager');
      $language_manager->setConfigOverrideLanguage($language_manager->getLanguage('fr'));
    }

    $formatted_date = $this->dateRangeCompactFormatter->formatDateRange($start, $end, 'date_and_time_range_with_tz', NULL, $langcode);

Thanks for reporting this.

$formatted_date = $this->dateRangeCompactFormatter->formatDateRange($start, $end, 'date_and_time_range_with_tz', 'America/Toronto', $langcode);

Firstly, what is the value of $langcode at this point?

Second, please can you paste the contents of daterange_compact.format.date_and_time_range_with_tz.yml?

$language_manager->setConfigOverrideLanguage($language_manager->getLanguage('fr'));

You shouldn't need to do this. The low level formatter should set this (and set it back afterwards). There is precedence for this in core, in user_mail(), which does something similar.

Calling formatDateRange($start, $end, 'date_and_time_range_with_tz', NULL, 'fr') should be enough and do what you expect.

I think the current MR fixes this.

Testing this and it fixes the language issue however I have a fix for timezone.

Patch from MR

Sorry I don't have any test code to offer atm, but probably pretty easy to cook up.

Thanks @joseph.olstad, glad to hear the language part is working :)

   public function formatDateRange(string $startDate, string $endDate, string $type = 'medium_date', $timezone = NULL, $langcode = NULL): FormattedDateTimeRange {
-    $startTimestamp = (new DrupalDateTime($startDate, $timezone))->getTimestamp();
-    $endTimestamp = (new DrupalDateTime($endDate, $timezone))->getTimestamp();
+    $startTimestamp = (new DrupalDateTime($startDate))->getTimestamp();
+    $endTimestamp = (new DrupalDateTime($endDate))->getTimestamp();
     return $this->formatTimestampRange($startTimestamp, $endTimestamp, $type, $timezone, $langcode);
   }

Why was $timezone removed here? It is breaking some tests.

On reflection, simply having any timezone parameter in formatDate() was wrong. But it is there now, and not easy to remove. So the best we can do is pass it through unchanged.

I added TimezoneTest to help get to the bottom of this. It calls the formatDate and formatTimestamp with various timezone values. It's failing (but passes if I revert #7). Can we start there and see if a) what that test expects is correct and b) if it covers your particular issue?

@erik.erskine it was 2 months ago now. From two months organic memory banks in my brain I do recall working on this and I recall the timezone getting double shifted before I made that change.

The timezone needs to be set once not twice.

With that said, it was 2 months ago.

However our approach was refactored and instead of using formatters we ended up using views instead to format our dates so we're no longer using the above patch due to our strict requirements of localisation. It had to be 100% localised perfectly to our spec for both our languages and at the time there were some edge cases that we solved using views instead.