test downloading old versions of a file

tests/acceptance/features/apiVersions/fileVersions.feature

@@ -415,3 +415,15 @@ Feature: dav-versions
     Then the HTTP status code should be "207"
     And the number of etag elements in the response should be "2"
     And the number of versions should be "2"
+
+
+  Scenario: download an old versions of a file
+    Given user "Alice" has uploaded file with content "uploaded content" to "textfile0.txt"
+    And user "Alice" has uploaded file with content "version 1" to "textfile0.txt"
+    And user "Alice" has uploaded file with content "version 2" to "textfile0.txt"
+    When user "Alice" downloads the version of file "textfile0.txt" with the index "0"
+    Then the HTTP status code should be "200"
+    And the downloaded content should be "version 1"
+    When user "Alice" downloads the version of file "textfile0.txt" with the index "1"
+    Then the HTTP status code should be "200"
+    And the downloaded content should be "uploaded content"

tests/acceptance/features/bootstrap/FilesVersionsContext.php

@@ -202,6 +202,36 @@ public function theContentLengthOfFileForUserInVersionsFolderIs(
 		);
 	}
 
+	/**
+	 * @When user :user downloads the version of file :path with the index :index
+	 *
+	 * @param string $user
+	 * @param string $path
+	 * @param string $index
+	 *
+	 * @return void
+	 */
+	public function downloadVersion(string $user, string $path, string $index) {
+		$user = $this->featureContext->getActualUsername($user);
+		$fileId = $this->featureContext->getFileIdForPath($user, $path);
+		$index = (int)$index;
+		$responseXml = $this->listVersionFolder($user, $fileId, 1);
+
+		//xpath index starts with 0 and the first reported href is the link to all versions, so need to add 2 here
+		$xmlPart = $responseXml->xpath("(//d:href)[" . ($index + 2) . "]");
+
+		// the href already contains the path
+		$url = WebDavHelper::sanitizeUrl(
+			$this->featureContext->getBaseUrlWithoutPath() . $xmlPart[0][0]
+		);
+		$response = HttpRequestHelper::get(
+			$url,
+			$user,
+			$this->featureContext->getPasswordForUser($user)
+		);
+		$this->featureContext->setResponse($response);
+	}
+
 	/**
 	 * returns the result parsed into an SimpleXMLElement
 	 * with an registered namespace with 'd' as prefix and 'DAV:' as namespace