Add Tanzania national holiday

src/Countries/Tanzania.php

@@ -0,0 +1,64 @@
+<?php
+
+namespace Spatie\Holidays\Countries;
+
+use Carbon\CarbonImmutable;
+use IntlCalendar;
+
+class Tanzania extends Country
+{
+    public function countryCode(): string
+    {
+        return 'tz';
+    }
+
+    protected function allHolidays(int $year): array
+    {
+        return array_merge([
+            'New Year\'s Day' => '01-01',
+            'Labor Day' => '05-01',
+            'Saba Saba Day' => '07-07',
+            'Farmers Day (Nane Nane Day)' => '08-08',
+            'Christmas Day' => '12-25',
+            'Boxing Day' => '12-26'
+        ], $this->variableHolidays($year));
+    }
+
+    /** @return array<string, string|CarbonImmutable> */
+    protected function variableHolidays(int $year): array
+    {
+        $easter = $this->easter($year);
+
+        $variable_holidays = [
+            'Easter Monday' => $easter->addDay(),
+            'Good Friday' => $easter->addDays(-2),
+        ];
+
+        // Zanzibar Revolutionary Day celebrations started in 1964
+        if ($year >= 1964) {
+            $variable_holidays['Zanzibar Revolutionary Day'] = '01-12';
+        }
+
+        // Karume Day celebrations started in 1973
+        if ($year >= 1973) {
+            $variable_holidays['Karume Day'] = '04-07';
+        }
+
+        //  'Union Day celebrations started in 1964
+        if ($year >= 1964) {
+            $variable_holidays['Union Day'] = '04-26';
+        }
+
+        // Nyerere Day day celebrations started in 2000
+        if ($year >= 2000) {
+            $variable_holidays['Nyerere Day'] = '10-14';
+        }
+
+        // Independence Day celebrations started in 1961
+        if ($year >= 1961) {
+            $variable_holidays['Independence Day'] = '12-09';
+        }
+
+        return $variable_holidays;
+    }
+}

tests/.pest/snapshots/Countries/TanzaniaTest/it_can_calculate_tanzania_holidays.snap

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+[
+    {
+        "name": "New Year's Day",
+        "date": "2024-01-01"
+    },
+    {
+        "name": "Zanzibar Revolutionary Day",
+        "date": "2024-01-12"
+    },
+    {
+        "name": "Good Friday",
+        "date": "2024-03-29"
+    },
+    {
+        "name": "Easter Monday",
+        "date": "2024-04-01"
+    },
+    {
+        "name": "Karume Day",
+        "date": "2024-04-07"
+    },
+    {
+        "name": "Union Day",
+        "date": "2024-04-26"
+    },
+    {
+        "name": "Labor Day",
+        "date": "2024-05-01"
+    },
+    {
+        "name": "Saba Saba Day",
+        "date": "2024-07-07"
+    },
+    {
+        "name": "Farmers Day (Nane Nane Day)",
+        "date": "2024-08-08"
+    },
+    {
+        "name": "Nyerere Day",
+        "date": "2024-10-14"
+    },
+    {
+        "name": "Independence Day",
+        "date": "2024-12-09"
+    },
+    {
+        "name": "Christmas Day",
+        "date": "2024-12-25"
+    },
+    {
+        "name": "Boxing Day",
+        "date": "2024-12-26"
+    }
+]

tests/Countries/TanzaniaTest.php

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