Added explicit test for rest batch publish

tests/AblyRestRequestTest.php

@@ -0,0 +1,65 @@
+<?php
+namespace tests;
+use Ably\AblyRest;
+require_once __DIR__ . '/factories/TestApp.php';
+
+class AblyRestRequestTest extends \PHPUnit\Framework\TestCase {
+
+    protected static $testApp;
+    protected static $defaultOptions;
+    protected static $ably;
+
+    public static function setUpBeforeClass(): void {
+        self::$testApp = new TestApp();
+        self::$defaultOptions = self::$testApp->getOptions();
+        self::$ably = new AblyRest( array_merge( self::$defaultOptions, [
+            'key' => self::$testApp->getAppKeyDefault()->string,
+        ] ) );
+    }
+
+    public static function tearDownAfterClass(): void {
+        self::$testApp->release();
+    }
+
+    /**
+     * Batch publishes messages for given list of channels
+     * RSC19
+     * https://ably.com/docs/api/rest-api#batch-publish
+     * @throws \Ably\Exceptions\AblyRequestException
+     */
+    public function testBatchPublishMultipleChannelsUsingPostRequest() {
+
+        $payload = array(
+            "channels" => ["channel1", "channel2", "channel3", "channel4"],
+            "messages" => array(
+                "id" => "1",
+                "data" => "foo"
+            )
+        );
+
+        $batchPublishPaginatedResult = self::$ably->request("POST","/messages", [], $payload);
+        $this->assertNotNull($batchPublishPaginatedResult);
+        $this->assertEquals(201, $batchPublishPaginatedResult->statusCode);
+        $this->assertTrue($batchPublishPaginatedResult->success);
+        $this->assertNull($batchPublishPaginatedResult->errorCode);
+        $this->assertNull($batchPublishPaginatedResult->errorMessage);
+        $this->assertTrue( $batchPublishPaginatedResult->isLast(), 'Expected not to be the last page' );
+
+        $this->assertEquals("application/x-msgpack", $batchPublishPaginatedResult->headers["Content-Type"]);
+        $this->assertCount(4, $batchPublishPaginatedResult->items);
+        foreach ($batchPublishPaginatedResult->items as $key=> $item) {
+            $this->assertEquals("channel".($key + 1), $item->channel);
+            $this->assertEquals(1, $item->messageId);
+        }
+
+        foreach (["channel1", "channel2", "channel3", "channel4"] as $channelName) {
+            print $channelName;
+            $channel = self::$ably->channel($channelName);
+            $paginatedHistory = $channel->history();
+            foreach ($paginatedHistory->items as $msg) {
+                $this->assertEquals("1", $msg->id);
+                $this->assertEquals("foo", $msg->data);
+            }
+        }
+    }
+}