Learnt from: PPsyrius
PR: #2643
File: holidays/countries/mauritius.py:144-169
Timestamp: 2025-06-19T02:34:18.382Z
Learning: Custom holiday classes that extend _CustomHinduHolidays, _CustomIslamicHolidays, _CustomBuddhistHolidays, etc. in the holidays library do not use docstrings. They follow a pattern of using only inline comments above date dictionaries, as seen in Malaysia, Singapore, UAE, and other country implementations.

Learnt from: PPsyrius
PR: #2614
File: holidays/countries/guyana.py:78-90
Timestamp: 2025-06-13T12:18:03.539Z
Learning: The holidays codebase now uses the constructor signature pattern __init__(self, *args, islamic_show_estimated: bool = True, **kwargs) across country classes.

Learnt from: KJhellico
PR: #2354
File: holidays/countries/fiji.py:171-183
Timestamp: 2025-03-29T15:15:05.919Z
Learning: In the Fiji holidays implementation, the maintainers are aware of the need to extend the MAWLID_DATES dictionary beyond 2025 when future official references become available, and will do so when appropriate. No suggestions about extending this dictionary should be made in future reviews.

Learnt from: PPsyrius
PR: #2537
File: holidays/countries/finland.py:0-0
Timestamp: 2025-05-10T04:32:15.760Z
Learning: In the holidays package, detailed historical context and additional information should be added as comments at the method level or above conditional blocks, while comments directly above tr() function calls should only contain the holiday name itself (e.g., "# Independence Day.").

Learnt from: PPsyrius
PR: #2354
File: holidays/countries/fiji.py:146-159
Timestamp: 2025-03-19T16:54:58.657Z
Learning: In the holidays library implementation, explicit holiday dates (like Diwali in Fiji) are only defined for historical years with official sources (2016-2025). Future dates beyond the explicitly defined range are automatically calculated by methods like _add_diwali, which provide approximations when official dates aren't yet available.

Learnt from: Wasif-Shahzad
PR: #2593
File: holidays/calendars/islamic.py:3993-3994
Timestamp: 2025-06-04T10:09:28.732Z
Learning: In the holidays/calendars/islamic.py file, the Islamic calendar date methods in the _IslamicLunar class (like ali_al_rida_death_dates, ashura_dates, etc.) follow a consistent pattern of being single-line methods that return self._get_holiday(CONSTANT, year) without docstrings. New methods should follow this same pattern for consistency.

Learnt from: KJhellico
PR: #2465
File: holidays/countries/suriname.py:219-251
Timestamp: 2025-04-13T19:10:31.502Z
Learning: The _CustomIslamicHolidays classes in this project contain only exact verified holiday dates from reliable sources, rather than calculated or estimated future dates. This is by design to ensure accuracy, particularly for religious holidays that may follow lunar calendars or depend on local observations.

Learnt from: PPsyrius
PR: #2489
File: holidays/countries/sao_tome_and_principe.py:22-26
Timestamp: 2025-04-23T14:55:35.504Z
Learning: References in holidays classes should only be included if they're used for test case cross-checks or provide historical context about when holidays were added/removed, not just for the sake of having more references.

Learnt from: PPsyrius
PR: #2489
File: holidays/countries/sao_tome_and_principe.py:22-26
Timestamp: 2025-04-23T14:55:35.504Z
Learning: References in holidays classes should only be included if they're used for test case cross-checks or provide historical context about when holidays were added/removed, not just for the sake of having more references.

Learnt from: PPsyrius
PR: #2643
File: holidays/countries/mauritius.py:171-184
Timestamp: 2025-06-19T02:34:14.456Z
Learning: In the holidays library, _CustomIslamicHolidays subclasses follow a consistent pattern of NOT having docstrings. They go directly to defining date dictionaries, as evidenced by Malaysia, Singapore, UAE, and dozens of other country implementations.

Learnt from: PPsyrius
PR: #2402
File: holidays/countries/trinidad_and_tobago.py:25-25
Timestamp: 2025-04-02T04:54:07.204Z
Learning: For English-speaking countries in the holidays library (like Trinidad and Tobago), the default_language and supported_languages parameters are optional. If languages are added for such countries, ensure that en_US is included in the list alongside the regional code variant (e.g., en_TT for Trinidad and Tobago).

Learnt from: Wasif-Shahzad
PR: #2593
File: holidays/countries/senegal.py:102-147
Timestamp: 2025-06-04T10:05:58.754Z
Learning: For Senegal holidays: Ashura (10 Muharram) in 2024 falls on July 17th, not July 16th. The user Wasif-Shahzad confirmed this date is correct for Senegal specifically, as Islamic holiday dates can vary by country based on local religious authorities and moon sighting practices.

Learnt from: Wasif-Shahzad
PR: #2522
File: holidays/countries/yemen.py:158-163
Timestamp: 2025-05-06T13:01:22.693Z
Learning: In the holidays library, the RAMADAN_BEGINNING_DATES dictionary in country-specific Islamic holiday classes (like YemenIslamicHolidays) is used indirectly through the backend. When a country class calls _add_holiday_29_ramadan(), the IslamicHolidays implementation uses the country's custom calendar dates to calculate the 29th day of Ramadan by adding 28 days to the beginning date.

Learnt from: KJhellico
PR: #2614
File: holidays/countries/guyana.py:146-179
Timestamp: 2025-06-14T20:12:37.212Z
Learning: The _CustomHinduHolidays mechanism works through _CustomCalendarType metaclass which renames public attributes (like DIWALI_INDIA_DATES) with a postfix, allowing _HinduLunisolar::_get_holiday to find and use custom holiday dates. When _add_diwali_india() is called, it uses the custom dates if available rather than calculated dates.

Learnt from: KJhellico
PR: #2614
File: holidays/countries/guyana.py:146-179
Timestamp: 2025-06-14T20:12:37.212Z
Learning: The _CustomHinduHolidays mechanism works through _CustomCalendarType metaclass which renames public attributes (like DIWALI_INDIA_DATES) with a postfix, allowing _HinduLunisolar::_get_holiday to find and use custom holiday dates. When _add_diwali_india() is called, it uses the custom dates if available rather than calculated dates.

Learnt from: KJhellico
PR: #2386
File: holidays/countries/nepal.py:266-284
Timestamp: 2025-04-13T20:41:56.613Z
Learning: The Islamic holiday dates in the holidays library should only include officially verified dates, not predicted ones, to maintain accuracy. This is especially important for holidays that depend on lunar observations like Eid al-Fitr and Eid al-Adha.

Learnt from: KJhellico
PR: #2398
File: holidays/countries/guinea.py:106-110
Timestamp: 2025-04-04T10:52:41.546Z
Learning: In the Guinea holidays implementation, observed Eid al-Fitr cases are properly covered by the test_eid_al_fitr_day() method, which tests both the regular holiday dates and the observed dates when the holiday falls on a non-working day (for years >= 2023).

Learnt from: KJhellico
PR: #2398
File: holidays/countries/guinea.py:106-110
Timestamp: 2025-04-04T10:52:41.546Z
Learning: In the Guinea holidays implementation, observed Eid al-Fitr cases are covered by the test_eid_al_fitr_day() method, which tests both regular holiday dates and the observed dates when the holiday falls on a non-working day (for years >= 2023).

Learnt from: PPsyrius
PR: #2706
File: holidays/countries/cayman_islands.py:80-97
Timestamp: 2025-07-10T03:36:16.461Z
Learning: In the holidays library, date dictionaries that map years to specific dates (like queens_birthday_dates, spring_bank_dates, thanksgiving_day_dates, etc.) are typically defined within the _populate_public_holidays method rather than as module-level constants. This is the established library-wide pattern seen across multiple country implementations including United Kingdom, United States, Sri Lanka, and others.

Learnt from: KJhellico
PR: #2398
File: holidays/countries/guinea.py:101-106
Timestamp: 2025-04-03T13:03:16.558Z
Learning: For Islamic holidays in Guinea like "Lendemain de la nuit Lailatoul Qadr" (Day after Night of Power) and "Lendemain de la nuit du Maoloud" (Day after Prophet's Birthday), the naming refers to the daylight hours following the night when these Islamic observances occur. Since in the Islamic calendar days begin at sunset rather than midnight, methods like _add_laylat_al_qadr_day and _add_mawlid_day correctly calculate these dates without requiring an additional day offset in the implementation.

Learnt from: PPsyrius
PR: #2706
File: holidays/countries/cayman_islands.py:80-97
Timestamp: 2025-07-10T03:36:16.461Z
Learning: In the holidays library, date dictionaries that map years to specific dates (like queens_birthday_dates, special holiday dates, etc.) are typically defined within the _populate_public_holidays method rather than as module-level constants. This is the established library-wide pattern and should be maintained for consistency.

Learnt from: KJhellico
PR: #2398
File: holidays/countries/guinea.py:101-106
Timestamp: 2025-04-03T13:03:16.558Z
Learning: For Islamic holidays in Guinea like "Lendemain de la nuit Lailatoul Qadr" (Day after Night of Power) and "Lendemain de la nuit du Maoloud" (Day after Prophet's Birthday), the naming refers to the daylight hours following the night when these Islamic observances occur. Since in the Islamic calendar days begin at sunset rather than midnight, methods like _add_laylat_al_qadr_day and _add_mawlid_day correctly calculate these dates without requiring an additional day offset in the implementation, following the same pattern as in the Ivory Coast implementation.