'occ app:enable appname' should make it clear that an app was already enabled

[nodiscc]

Steps to reproduce

1. Enable an already enabled app through php ./occ app:enable appname

Expected behaviour

The command should succeed (return code 0) and return appname already enabled on the standard output.

Actual behaviour

The command succeeds but returns appname enabled, exactly the same message as when the app was not previously enabled. This makes it difficult to determine if the command actually changed something and prevents using occ in an idempotent way in configuration management tools (ansible).

In this regard app:disable appname works as expected as it returns No such app enabled: appname when the app was already disabled. This makes it possible to detect that nothing was changed.

Server configuration

Operating system: Debian GNU/Linux 10 Buster

Web server: Apache 2.4

Database: MySQL

PHP version: 7.3

Nextcloud version: 17.0

Updated from an older Nextcloud/ownCloud or fresh install: fresh install

Where did you install Nextcloud from: tarball at https://download.nextcloud.com/server/releases/nextcloud-17.0.0.zip

[kesselb]

Index: core/Command/App/Enable.php
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
--- core/Command/App/Enable.php	(revision 78d00ff0852a6199cc7ca33db6308f7bdd09b5a6)
+++ core/Command/App/Enable.php	(date 1572793732067)
@@ -98,6 +98,10 @@
 			return $group->getDisplayName();
 		}, $groupIds);
 
+		if ($this->appManager->isInstalled($appId)) {
+			$output->writeln($appId . ' already enabled');
+			return;
+		}
 
 		try {
 			/** @var Installer $installer */

Sounds good to me. Something like above should do the trick. If someone wants to pick this up please also adjust the test: https://github.com/nextcloud/server/blob/5b4155bd12764d0ee0f0380d49b66aa9ea2c7516/tests/Core/Command/Apps/AppsEnableTest.php

[sndrr]

I've added a PR. It also checks for group parameters, since that setting will impact the output.