tests/Formats: Simplify by using a base class (#2779)

There is a lot of redundancy. Let’s not repeat ourselves.

Unfortunately, since we do not install PHPUnit as a project dependency on CI,
it does not use the composer’s PSR-4 autoloader and the tests are unable to find
the `BaseFormatTest` class.

Until we resolve that, let’s load the class explicitly.

tests/Formats/BaseFormatTest.php

@@ -0,0 +1,64 @@
+<?php
+
+namespace RssBridge\Tests\Formats;
+
+use PHPUnit\Framework\TestCase;
+use FormatFactory;
+
+abstract class BaseFormatTest extends TestCase {
+	protected const PATH_SAMPLES = __DIR__ . '/samples/';
+
+	/**
+	 * @return array<string, array{string, string}>
+	 */
+	public function sampleProvider() {
+		$samples = [];
+		foreach (glob(self::PATH_SAMPLES . '*.json') as $path) {
+			$name = basename($path, '.json');
+			$samples[$name] = [
+				$name,
+				$path,
+			];
+		}
+		return $samples;
+	}
+
+	/**
+	 * Cannot be part of the sample returned by sampleProvider since this modifies $_SERVER
+	 * and thus needs to be run in a separate process to avoid side effects.
+	 */
+	protected function loadSample(string $path): \stdClass {
+		$data = json_decode(file_get_contents($path), true);
+		if (isset($data['meta']) && isset($data['items'])) {
+			if (!empty($data['server']))
+				$this->setServerVars($data['server']);
+
+			$items = array();
+			foreach($data['items'] as $item) {
+				$items[] = new \FeedItem($item);
+			}
+
+			return (object)array(
+				'meta' => $data['meta'],
+				'items' => $items,
+			);
+		} else {
+			$this->fail('invalid test sample: ' . basename($path, '.json'));
+		}
+	}
+
+	private function setServerVars(array $list): void {
+		$_SERVER = array_merge($_SERVER, $list);
+	}
+
+	protected function formatData(string $formatName, \stdClass $sample): string {
+		$formatFac = new FormatFactory();
+		$formatFac->setWorkingDir(PATH_LIB_FORMATS);
+		$format = $formatFac->create($formatName);
+		$format->setItems($sample->items);
+		$format->setExtraInfos($sample->meta);
+		$format->setLastModified(strtotime('2000-01-01 12:00:00 UTC'));
+
+		return $format->stringify();
+	}
+}