Add date unit tests

src/Common/Date.php

@@ -18,6 +18,13 @@ private function __construct(DateTimeImmutable $start, DateTimeImmutable|null $e
         $this->end = $end;
     }
 
+    public static function create(
+        DateTimeImmutable $start,
+        DateTimeImmutable $end = null,
+    ): self {
+        return new self($start, $end);
+    }
+
     /**
      * @param DateJson $array
      *
@@ -53,4 +60,19 @@ public function isRange(): bool
     {
         return $this->end !== null;
     }
+
+    public function withStart(DateTimeImmutable $start): self
+    {
+        return new self($start, $this->end);
+    }
+
+    public function withEnd(DateTimeImmutable $end): self
+    {
+        return new self($this->start, $end);
+    }
+
+    public function withoutEnd(): self
+    {
+        return new self($this->start, null);
+    }
 }

tests/Unit/Common/DateTest.php

@@ -0,0 +1,72 @@
+<?php
+
+namespace Notion\Test\Common;
+
+use DateTimeImmutable;
+use Notion\Common\Date;
+use PHPUnit\Framework\TestCase;
+
+class DateTest extends TestCase
+{
+    public function test_array_conversion(): void
+    {
+        $array = [
+            "start" => "2021-01-01",
+            "end"   => "2021-12-31",
+        ];
+
+        $date = Date::fromArray($array);
+        $this->assertEquals($array, $date->toArray());
+    }
+
+    public function test_create_date(): void
+    {
+        $start = new DateTimeImmutable("2021-01-01");
+        $date = Date::create($start);
+
+        $this->assertSame($start, $date->start());
+        $this->assertNull($date->end());
+        $this->assertFalse($date->isRange());
+    }
+
+    public function test_create_range(): void
+    {
+        $start = new DateTimeImmutable("2021-01-01");
+        $end = new DateTimeImmutable("2021-12-31");
+        $date = Date::create($start, $end);
+
+        $this->assertSame($start, $date->start());
+        $this->assertSame($end, $date->end());
+        $this->assertTrue($date->isRange());
+    }
+
+    public function test_change_start(): void
+    {
+        $oldStart = new DateTimeImmutable("2021-01-01");
+        $newStart = new DateTimeImmutable("2022-01-01");
+
+        $date = Date::create($oldStart)->withStart($newStart);
+
+        $this->assertSame($newStart, $date->start());
+    }
+
+    public function test_change_end(): void
+    {
+        $start = new DateTimeImmutable("2021-01-01");
+        $end = new DateTimeImmutable("2022-01-01");
+
+        $date = Date::create($start)->withEnd($end);
+
+        $this->assertSame($end, $date->end());
+    }
+
+    public function test_remove_end(): void
+    {
+        $start = new DateTimeImmutable("2021-01-01");
+        $end = new DateTimeImmutable("2021-12-31");
+        $date = Date::create($start, $end)->withoutEnd();
+
+        $this->assertNull($date->end());
+        $this->assertFalse($date->isRange());
+    }
+}