From eb6b4d8e7e6d9c63b3b987d852f631297a6e0d7f Mon Sep 17 00:00:00 2001
From: MGChecker <hgasuser@gmail.com>
Date: Tue, 28 Aug 2018 04:39:16 +0200
Subject: [PATCH] registration: Add ability to check if a specific extension
 version is loaded

As it's quite common that extensions and skins interact with each other, it's
useful to have a simple way to check if an extension version satisfies a
given constraint, as extensions change over time.

Bug: T202955
Change-Id: I19f9713caf89d647072a2bd7d598e739be383f4a
---
 includes/registration/ExtensionRegistry.php   | 20 +++++++++++++++++--
 .../data/registration/good_with_version.json  | 13 ++++++++++++
 .../registration/ExtensionRegistryTest.php    | 19 ++++++++++++++++++
 3 files changed, 50 insertions(+), 2 deletions(-)
 create mode 100644 tests/phpunit/data/registration/good_with_version.json

diff --git a/includes/registration/ExtensionRegistry.php b/includes/registration/ExtensionRegistry.php
index d21ae412f1..8429afa843 100644
--- a/includes/registration/ExtensionRegistry.php
+++ b/includes/registration/ExtensionRegistry.php
@@ -1,5 +1,7 @@
 <?php
 
+use Composer\Semver\Semver;
+
 /**
  * ExtensionRegistry class
  *
@@ -381,10 +383,24 @@ class ExtensionRegistry {
 	/**
 	 * Whether a thing has been loaded
 	 * @param string $name
+	 * @param string $constraint The required version constraint for this dependency
+	 * @throws LogicException if a specific contraint is asked for,
+	 *                        but the extension isn't versioned
 	 * @return bool
 	 */
-	public function isLoaded( $name ) {
-		return isset( $this->loaded[$name] );
+	public function isLoaded( $name, $constraint = '*' ) {
+		$isLoaded = isset( $this->loaded[$name] );
+		if ( $constraint === '*' || !$isLoaded ) {
+			return $isLoaded;
+		}
+		// if a specific constraint is requested, but no version is set, throw an exception
+		if ( !isset( $this->loaded[$name]['version'] ) ) {
+			$msg = "{$name} does not expose its version, but an extension or a skin"
+					. " requires: {$constraint}.";
+			throw new LogicException( $msg );
+		}
+
+		return SemVer::satisfies( $this->loaded[$name]['version'], $constraint );
 	}
 
 	/**
diff --git a/tests/phpunit/data/registration/good_with_version.json b/tests/phpunit/data/registration/good_with_version.json
new file mode 100644
index 0000000000..586ba7ccb8
--- /dev/null
+++ b/tests/phpunit/data/registration/good_with_version.json
@@ -0,0 +1,13 @@
+{
+	"name": "FooBar",
+	"version": "1.2.3",
+	"attributes": {
+		"FooBar": {
+			"Attr": [ "test" ]
+		},
+		"NotLoaded": {
+			"Attr": [ "test2" ]
+		}
+	},
+	"manifest_version": 2
+}
diff --git a/tests/phpunit/includes/registration/ExtensionRegistryTest.php b/tests/phpunit/includes/registration/ExtensionRegistryTest.php
index 7120a91a97..1baa79c160 100644
--- a/tests/phpunit/includes/registration/ExtensionRegistryTest.php
+++ b/tests/phpunit/includes/registration/ExtensionRegistryTest.php
@@ -57,10 +57,29 @@ class ExtensionRegistryTest extends MediaWikiTestCase {
 		$registry->loadFromQueue();
 		$this->assertArrayHasKey( 'FooBar', $registry->getAllThings() );
 		$this->assertTrue( $registry->isLoaded( 'FooBar' ) );
+		$this->assertTrue( $registry->isLoaded( 'FooBar', '*' ) );
 		$this->assertSame( [ 'test' ], $registry->getAttribute( 'FooBarAttr' ) );
 		$this->assertSame( [], $registry->getAttribute( 'NotLoadedAttr' ) );
 	}
 
+	public function testLoadFromQueueWithConstraintWithVersion() {
+		$registry = new ExtensionRegistry();
+		$registry->queue( "{$this->dataDir}/good_with_version.json" );
+		$registry->loadFromQueue();
+		$this->assertTrue( $registry->isLoaded( 'FooBar', '>= 1.2.0' ) );
+		$this->assertFalse( $registry->isLoaded( 'FooBar', '^1.3.0' ) );
+	}
+
+	/**
+	 * @expectedException LogicException
+	 */
+	public function testLoadFromQueueWithConstraintWithoutVersion() {
+		$registry = new ExtensionRegistry();
+		$registry->queue( "{$this->dataDir}/good.json" );
+		$registry->loadFromQueue();
+		$registry->isLoaded( 'FooBar', '>= 1.2.0' );
+	}
+
 	/**
 	 * @expectedException PHPUnit_Framework_Error
 	 */
-- 
2.20.1