Add isEqualTo test coverage for weekday

tests/Weekday/IsEqualToTest.php

@@ -0,0 +1,56 @@
+<?php
+
+declare(strict_types=1);
+
+namespace DigitalCraftsman\DateTimePrecision\Weekday;
+
+use DigitalCraftsman\DateTimePrecision\Weekday;
+use PHPUnit\Framework\TestCase;
+
+/** @coversDefaultClass \DigitalCraftsman\DateTimePrecision\Weekday */
+final class IsEqualToTest extends TestCase
+{
+    /**
+     * @test
+     *
+     * @dataProvider dataProvider
+     *
+     * @covers ::isEqualTo
+     */
+    public function is_equal_to_works(
+        bool $expectedResult,
+        Weekday $weekday,
+        Weekday $comparator,
+    ): void {
+        // -- Act & Assert
+        self::assertSame($expectedResult, $weekday->isEqualTo($comparator));
+    }
+
+    /**
+     * @return array<string, array{
+     *   0: boolean,
+     *   1: Weekday,
+     *   2: Weekday,
+     * }>
+     */
+    public static function dataProvider(): array
+    {
+        return [
+            '1 day before' => [
+                false,
+                Weekday::MONDAY,
+                Weekday::TUESDAY,
+            ],
+            'same day' => [
+                true,
+                Weekday::TUESDAY,
+                Weekday::TUESDAY,
+            ],
+            '1 day later' => [
+                false,
+                Weekday::TUESDAY,
+                Weekday::MONDAY,
+            ],
+        ];
+    }
+}