PHPUnit 10 Migration (#1302)

* Bump PHPUnit dependencies

* Set return type of base TestCase methods

From the [PHPUnit 8 release notes][1], the `TestCase` methods below now declare a `void` return type:

- `setUpBeforeClass()`
- `setUp()`
- `assertPreConditions()`
- `assertPostConditions()`
- `tearDown()`
- `tearDownAfterClass()`
- `onNotSuccessfulTest()`

[1]: https://phpunit.de/announcements/phpunit-8.html

* Ignore PHPUnit cache folder

* Adopt PHP attributes in test classes

* Declare data providers as `static`

* Add return types to test methods

* Define test classes as `final`

* Migrate phpunit.xml to phpunit 10

* Correct phpunit attribute class name

* Rename base test class

* Restructure test folders

* Fix test image paths

* Only set rules for php files in .editorconfig

* Remove php unit flag in local test env

---------

Co-authored-by: Shift <shift@laravelshift.com>

tests/Unit/Typography/LineTest.php

@@ -0,0 +1,61 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Intervention\Image\Tests\Unit\Typography;
+
+use Intervention\Image\Geometry\Point;
+use Intervention\Image\Tests\BaseTestCase;
+use Intervention\Image\Typography\Line;
+
+final class LineTest extends BaseTestCase
+{
+    public function testConstructor(): void
+    {
+        $line = new Line('foo');
+        $this->assertInstanceOf(Line::class, $line);
+    }
+
+    public function testToString(): void
+    {
+        $line = new Line('foo bar');
+        $this->assertEquals('foo bar', (string) $line);
+    }
+
+    public function testSetGetPosition(): void
+    {
+        $line = new Line('foo');
+        $this->assertEquals(0, $line->position()->x());
+        $this->assertEquals(0, $line->position()->y());
+
+        $line->setPosition(new Point(10, 11));
+        $this->assertEquals(10, $line->position()->x());
+        $this->assertEquals(11, $line->position()->y());
+    }
+
+    public function testCount(): void
+    {
+        $line = new Line();
+        $this->assertEquals(0, $line->count());
+
+        $line = new Line("foo");
+        $this->assertEquals(1, $line->count());
+
+        $line = new Line("foo bar");
+        $this->assertEquals(2, $line->count());
+    }
+
+    public function testAdd(): void
+    {
+        $line = new Line();
+        $this->assertEquals(0, $line->count());
+
+        $result = $line->add('foo');
+        $this->assertEquals(1, $line->count());
+        $this->assertEquals(1, $result->count());
+
+        $result = $line->add('bar');
+        $this->assertEquals(2, $line->count());
+        $this->assertEquals(2, $result->count());
+    }
+}