Add Bangladesh holidays (#21)

Co-authored-by: Ariful Alam <ariful.dev@miaki.com.bd>

src/Countries/Bangladesh.php

@@ -0,0 +1,35 @@
+<?php
+
+namespace Spatie\Holidays\Countries;
+
+use Carbon\CarbonImmutable;
+
+class Bangladesh extends Country
+{
+    public function countryCode(): string
+    {
+        return 'bd';
+    }
+
+    /** @return array<string, CarbonImmutable> */
+    protected function allHolidays(int $year): array
+    {
+        return array_merge([
+            'International Mother Language Day' => '02-21',
+            'Birthday of Sheikh Mujibur Rahman' => '03-17',
+            'Independence Day' => '03-26',
+            'Bengali New Year' => '04-14',
+            'May Day' => '05-01',
+            'National Mourning Day' => '08-15',
+            'Victory Day' => '12-16',
+            'Christmas Day' => '12-25',
+        ], $this->variableHolidays($year));
+    }
+
+    /** @return array<string, CarbonImmutable> */
+    protected function variableHolidays(int $year): array
+    {
+        // The variable holidays all follow the lunar calendar, so their dates are not confirmed.
+        return [];
+    }
+}

tests/.pest/snapshots/Countries/BangladeshTest/it_can_calculate_bangladesh_holidays.snap

@@ -0,0 +1,34 @@
+[
+    {
+        "name": "International Mother Language Day",
+        "date": "2024-02-21"
+    },
+    {
+        "name": "Birthday of Sheikh Mujibur Rahman",
+        "date": "2024-03-17"
+    },
+    {
+        "name": "Independence Day",
+        "date": "2024-03-26"
+    },
+    {
+        "name": "Bengali New Year",
+        "date": "2024-04-14"
+    },
+    {
+        "name": "May Day",
+        "date": "2024-05-01"
+    },
+    {
+        "name": "National Mourning Day",
+        "date": "2024-08-15"
+    },
+    {
+        "name": "Victory Day",
+        "date": "2024-12-16"
+    },
+    {
+        "name": "Christmas Day",
+        "date": "2024-12-25"
+    }
+]

tests/Countries/BangladeshTest.php

@@ -0,0 +1,18 @@
+<?php
+
+namespace Spatie\Holidays\Tests\Countries;
+
+use Carbon\CarbonImmutable;
+use Spatie\Holidays\Holidays;
+
+it('can calculate bangladesh holidays', function () {
+    CarbonImmutable::setTestNowAndTimezone('2024-01-01');
+
+    $holidays = Holidays::for(country: 'bd')->get();
+
+    expect($holidays)
+        ->toBeArray()
+        ->not()->toBeEmpty();
+
+    expect(formatDates($holidays))->toMatchSnapshot();
+});