Add ability to load filters from partials

Issue #12

tests/Unit/Service/PartialsTest.php

@@ -0,0 +1,36 @@
+<?php
+
+namespace Opdavies\Tests\GmailFilterBuilder\Service;
+
+use Opdavies\GmailFilterBuilder\Model\Filter;
+use Opdavies\GmailFilterBuilder\Service\Partials;
+use PHPUnit\Framework\TestCase;
+
+class PartialsTest extends TestCase
+{
+    /**
+     * Test loading partials from multiple partial files.
+     */
+    public function testLoadingFiltersFromPartials()
+    {
+        /** @var Filter[] $filters */
+        $filters = FakePartials::load('filters');
+
+        $this->assertCount(3, $filters);
+
+        $this->assertSame('foo@example.com', $filters[0]->getProperties()['from'][0]);
+        $this->assertSame('bar@example.com', $filters[1]->getProperties()['from'][0]);
+        $this->assertSame('baz@example.com', $filters[2]->getProperties()['from'][0]);
+    }
+}
+
+class FakePartials extends Partials
+{
+    /**
+     * {@inheritdoc}
+     */
+    protected function getFilePattern(string $directoryName)
+    {
+        return __DIR__ . '/../../stubs/filters/*.php';
+    }
+}

tests/stubs/filters/a.php

@@ -0,0 +1,13 @@
+<?php
+
+use Opdavies\GmailFilterBuilder\Model\Filter;
+
+return [
+    Filter::create()
+        ->from('foo@example.com')
+        ->labelAndArchive('Test'),
+
+    Filter::create()
+        ->from('bar@example.com')
+        ->labelAndArchive('Test 2'),
+];

tests/stubs/filters/b.php

@@ -0,0 +1,9 @@
+<?php
+
+use Opdavies\GmailFilterBuilder\Model\Filter;
+
+return [
+    Filter::create()
+        ->from('baz@example.com')
+        ->labelAndArchive('Test 3'),
+];