Add ability to load filters from partials

Issue #12

src/Service/Partials.php

@@ -0,0 +1,43 @@
+<?php
+
+namespace Opdavies\GmailFilterBuilder\Service;
+
+/**
+ * Load and combine partials from multiple files.
+ */
+class Partials
+{
+    /**
+     * Load partials from a directory.
+     *
+     * @param string $directoryName The name of the directory containing the partials.
+     *
+     * @return array The loaded filters.
+     */
+    public static function load($directoryName = 'filters')
+    {
+        $files = (new static())->getFilePattern($directoryName);
+
+        return collect(glob($files))
+            ->map(function (string $filename) {
+                return include $filename;
+            })
+            ->flatten(1)
+            ->all();
+    }
+
+    /**
+     * Build the glob pattern to load partials from the directory.
+     *
+     * Assumes it is always relative to the current directory, and that the
+     * filters are always in files with a .php extension.
+     *
+     * @param string $directoryName The name of the directory.
+     *
+     * @return string The full path.
+     */
+    protected function getFilePattern(string $directoryName)
+    {
+        return __DIR__ . DIRECTORY_SEPARATOR . $directoryName . DIRECTORY_SEPARATOR . '/*.php';
+    }
+}

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'),
+];