feat: #2386 - added tests about localization parameters

[monsieurtanuki]

Impacted file:

• plural_translation_test.dart: added tests about localization parameters; simplified

What

• Tests were added for all labels that currently need parameters.
• If new labels with parameters appear, they need to be added there too.
• Good news: the tests currently fail, for 6 languages.

Fixes bug(s)

• Closes: Add a test that placeholder are preserved in translations #2386

[teolemon]

Not sure how we fail fil while having 0% translations: https://crowdin.com/project/openfoodfacts/fil

══╡ EXCEPTION CAUGHT BY FLUTTER TEST FRAMEWORK ╞════════════════════════════════════════════════════
The following TestFailure was thrown running a test:
Expected: contains '2080706050'
Actual: 'One product'
When the exception was thrown, this was the stack:
#4 main.. (file:///home/runner/work/smooth-app/smooth-app/packages/smooth_app/test/plural_translation_test.dart:214:11)
#5 main.. (file:///home/runner/work/smooth-app/smooth-app/packages/smooth_app/test/plural_translation_test.dart:18:42)
#6 testWidgets.. (package:flutter_test/src/widget_tester.dart:170:29)


(elided one frame from package:stack_trace)
This was caught by the test expectation on the following line:
file:///home/runner/work/smooth-app/smooth-app/packages/smooth_app/test/plural_translation_test.dart line 214
The test description was:
plural test fil
════════════════════════════════════════════════════════════════════════════════════════════════════

[monsieurtanuki]

Not sure how we fail fil while having 0% translations: https://crowdin.com/project/openfoodfacts/fil

I didn't understand either, I did double-check, and at least for this label it's exactly the same as in English.
There are 3 languages that fail for user_list_length.

After investigations, it's because there's a specific way to deal with plurals in fil, lv and tl.
cf. https://github.com/dart-lang/intl/blob/master/lib/src/plural_rules.dart#L132-L139

/// The integer part of [_n]
int _i = 0;
/// Number of visible fraction digits.
int _v = 0;
/// The visible fraction digits in n, with trailing zeros.
int _f = 0;

PluralCase _fil_rule() {
  if (_v == 0 && (_i == 1 || _i == 2 || _i == 3) ||
      _v == 0 && _i % 10 != 4 && _i % 10 != 6 && _i % 10 != 9 ||
      _v != 0 && _f % 10 != 4 && _f % 10 != 6 && _f % 10 != 9) {
    return ONE;
  }
  return OTHER;
}

And my crazy int was 2080706050 (_v == 0 && _i % 10 != 4 && _i % 10 != 6 && _i % 10 != 9 is true, therefore it's like 1).
I've changed the value in my PR, and it works! I mean, other values still fail, but for good reasons!

[teolemon]

══╡ EXCEPTION CAUGHT BY FLUTTER TEST FRAMEWORK ╞════════════════════════════════════════════════════
The following TestFailure was thrown running a test:
Expected: contains 'の中ழ்'
Actual: 'Open Food Facts でこの製品を見る:'

(ja)

══╡ EXCEPTION CAUGHT BY FLUTTER TEST FRAMEWORK ╞════════════════════════════════════════════════════
The following TestFailure was thrown running a test:
Expected: contains 'の中ழ்'
Actual: 'процентне співвідношення'

(uk)

id
══╡ EXCEPTION CAUGHT BY FLUTTER TEST FRAMEWORK ╞════════════════════════════════════════════════════
The following TestFailure was thrown running a test:
Expected: contains 'の中ழ்'
Actual: 'Selanjutnya { source_name}'

[codecov-commenter]

Codecov Report

Merging #2412 (d045569) into develop (2ea0da3) will decrease coverage by 1.33%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           develop   #2412      +/-   ##
==========================================
- Coverage     8.86%   7.52%   -1.34%     
==========================================
  Files          161     204      +43     
  Lines         6623    9769    +3146     
==========================================
+ Hits           587     735     +148     
- Misses        6036    9034    +2998     

Impacted Files	Coverage Δ
...kages/smooth_app/lib/widgets/attribute_button.dart	0.00% <0.00%> (-92.00%)	⬇️
...s/smooth_app/lib/data_models/user_preferences.dart	8.73% <0.00%> (-23.57%)	⬇️
packages/smooth_app/lib/themes/smooth_theme.dart	60.00% <0.00%> (-22.98%)	⬇️
...p/lib/generic_lib/dialogs/smooth_alert_dialog.dart	15.29% <0.00%> (-18.92%)	⬇️
...mooth_app/lib/data_models/product_preferences.dart	24.65% <0.00%> (-6.78%)	⬇️
packages/smooth_app/lib/main.dart	14.40% <0.00%> (-3.49%)	⬇️
.../smooth_app/lib/pages/onboarding/welcome_page.dart	0.00% <0.00%> (-3.13%)	⬇️
.../smooth_app/lib/pages/onboarding/scan_example.dart	0.00% <0.00%> (-2.28%)	⬇️
...p/lib/pages/onboarding/consent_analytics_page.dart	0.00% <0.00%> (-1.57%)	⬇️
...smooth_app/lib/pages/product/new_product_page.dart	0.00% <0.00%> (-0.88%)	⬇️
... and 204 more

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[monsieurtanuki]

@teolemon For the record, you fixed pct_match in uk as "".
Of course it failed, because we expect to see the percentage, like in English: "{percent}% match".
That's even the purpose of this PR.
You were testing me, fair enough ;)
In general, a no brainer fix would be to put the English translation.
Feel free to approve this PR.

[M123-dev]

This and the following with empfehlen strings doesn't necessarily assure that all of the variables are still valid in all languages. We should check if crazyInt is in it 6 times if there is a check for it

[monsieurtanuki]

@M123-dev I don't agree with you: I test if each parameter is displayed. Good enough is good enough.
What you suggest would mean that in some cases, the translation tool mistakes a parameter for another, which is very unlikely.
Anyway, that test set is a start, and is open to evolution.