diff --git a/src/ExternalLibrary/Asset/LocalRemoteAssetTrait.php b/src/ExternalLibrary/Asset/LocalRemoteAssetTrait.php
index 15eb3c3e25098b7e16d87e46ee74f7075ec15934..62b8334a0320ba374feb21f32d56b6447525a27c 100644
--- a/src/ExternalLibrary/Asset/LocalRemoteAssetTrait.php
+++ b/src/ExternalLibrary/Asset/LocalRemoteAssetTrait.php
@@ -69,6 +69,28 @@ trait LocalRemoteAssetTrait {
     return ($this->isInstalled() || $this->hasRemoteUrl());
   }
 
+  /**
+   * Gets the prefix to prepend to file paths.
+   *
+   * For local libraries this is the library path, for remote libraries this is
+   * the remote URL.
+   *
+   * @return string
+   *   The path prefix.
+   */
+  protected function getPathPrefix() {
+    /** @var \Drupal\libraries\ExternalLibrary\Local\LocalLibraryInterface|\Drupal\libraries\ExternalLibrary\Remote\RemoteLibraryInterface $this */
+    if ($this->isInstalled()) {
+      return $this->getLocalPath();
+    }
+    elseif ($this->hasRemoteUrl()) {
+      return $this->getRemoteUrl();
+    }
+    else {
+      // @todo Throw an exception.
+    }
+  }
+
   /**
    * Gets the CSS assets attached to this library.
    *
@@ -84,8 +106,15 @@ trait LocalRemoteAssetTrait {
    * @see \Drupal\libraries\ExternalLibrary\Asset\SingleAssetLibraryTrait::getCssAssets()
    */
   protected function getCssAssets() {
-    // @todo Process the paths.
-    return $this->cssAssets;
+    // @todo Consider somehow caching the processed information.
+    $processed_assets = [];
+    foreach ($this->cssAssets as $category => $category_assets) {
+      // @todo Somehow consolidate this with getJsAssets().
+      foreach ($category_assets as $filename => $options) {
+        $processed_assets[$category][$this->getPathPrefix() . '/' . $filename] = $options;
+      }
+    }
+    return $processed_assets;
   }
 
   /**
@@ -99,8 +128,13 @@ trait LocalRemoteAssetTrait {
    * @see \Drupal\libraries\ExternalLibrary\Asset\SingleAssetLibraryTrait::getJsAssets()
    */
   protected function getJsAssets() {
-    // @todo Process the paths.
-    return $this->jsAssets;
+    // @todo Consider somehow caching the processed information.
+    $processed_assets = [];
+    // @todo Somehow consolidate this with getCssAssets().
+    foreach ($this->jsAssets as $filename => $options) {
+      $processed_assets[$this->getPathPrefix() . '/' . $filename] = $options;
+    }
+    return $processed_assets;
   }
 
 }
diff --git a/tests/library_definitions/test_asset_library.json b/tests/library_definitions/test_asset_library.json
index 61e2d6f854d8ea02f64eacea2a472c24bc293343..da7eeee4dcd1d8ad6e10014d03e225e343aa52c3 100644
--- a/tests/library_definitions/test_asset_library.json
+++ b/tests/library_definitions/test_asset_library.json
@@ -3,7 +3,9 @@
   "class": "Drupal\\libraries\\ExternalLibrary\\Asset\\AssetLibrary",
   "remote_url": "http://example.com",
   "css": {
-    "example.css": []
+    "base": {
+      "example.css": []
+    }
   },
   "js": {
     "example.js": []
diff --git a/tests/src/Kernel/ExternalLibrary/Asset/AssetLibraryTest.php b/tests/src/Kernel/ExternalLibrary/Asset/AssetLibraryTest.php
index b38a5fcaab2a8c1676d01ee3ca6ef5858d2b873d..884801c838129b73e3268e89397da27e9d1e1b0e 100644
--- a/tests/src/Kernel/ExternalLibrary/Asset/AssetLibraryTest.php
+++ b/tests/src/Kernel/ExternalLibrary/Asset/AssetLibraryTest.php
@@ -7,6 +7,9 @@
 
 namespace Drupal\Tests\libraries\Kernel\ExternalLibrary\Asset;
 
+use Drupal\libraries\ExternalLibrary\Asset\AssetLibrary;
+use Drupal\libraries\ExternalLibrary\Exception\LibraryClassNotFoundException;
+use Drupal\libraries\ExternalLibrary\Exception\LibraryDefinitionNotFoundException;
 use Drupal\Tests\libraries\Kernel\ExternalLibraryKernelTestBase;
 
 /**
@@ -40,6 +43,32 @@ class AssetLibraryTest extends ExternalLibraryKernelTestBase {
     $this->libraryDiscovery = $this->container->get('library.discovery');
   }
 
+  /**
+   * Tests that library metadata is correctly gathered.
+   */
+  public function testMetadata() {
+    try {
+      /** @var \Drupal\libraries\ExternalLibrary\Asset\AssetLibrary $library */
+      $library = $this->externalLibraryRegistry->getLibrary('test_asset_library');
+      $this->assertInstanceOf(AssetLibrary::class, $library);
+
+      $this->assertEquals('test_asset_library', $library->getId());
+      $expected = ['test_asset_library' => [
+        'version' => 1.0,
+        'css' => ['base' => ['http://example.com/example.css' => []]],
+        'js' => ['http://example.com/example.js' => []],
+        'dependencies' => [],
+      ]];
+      $this->assertEquals($expected, $library->getAttachableAssetLibraries());
+    }
+    catch (LibraryClassNotFoundException $exception) {
+      $this->fail();
+    }
+    catch (LibraryDefinitionNotFoundException $exception) {
+      $this->fail();
+    }
+  }
+
   /**
    * Tests that an external asset library is registered as a core asset library.
    *
diff --git a/tests/src/Kernel/ExternalLibrary/PhpFile/PhpFileLibraryTest.php b/tests/src/Kernel/ExternalLibrary/PhpFile/PhpFileLibraryTest.php
index f257c32920480118e530d20a1f09ce4e7c1ddd75..7a719a20ffd4b39a54ca5f3b815cb9e07104990a 100644
--- a/tests/src/Kernel/ExternalLibrary/PhpFile/PhpFileLibraryTest.php
+++ b/tests/src/Kernel/ExternalLibrary/PhpFile/PhpFileLibraryTest.php
@@ -7,7 +7,6 @@
 
 namespace Drupal\Tests\libraries\Kernel\ExternalLibrary\PhpFile;
 
-use Drupal\Core\Asset\Exception\LibraryDefinitionMissingLicenseException;
 use Drupal\libraries\ExternalLibrary\Exception\LibraryClassNotFoundException;
 use Drupal\libraries\ExternalLibrary\Exception\LibraryDefinitionNotFoundException;
 use Drupal\libraries\ExternalLibrary\PhpFile\PhpFileLibrary;
@@ -32,13 +31,6 @@ class PhpFileLibraryTest extends ExternalLibraryKernelTestBase {
    */
   protected $externalLibraryManager;
 
-  /**
-   * The external library registry.
-   *
-   * @var \Drupal\libraries\ExternalLibrary\Registry\ExternalLibraryRegistryInterface
-   */
-  protected $externalLibraryRegistry;
-
   /**
    * {@inheritdoc}
    */
@@ -46,7 +38,6 @@ class PhpFileLibraryTest extends ExternalLibraryKernelTestBase {
     parent::setUp();
 
     $this->externalLibraryManager = $this->container->get('libraries.manager');
-    $this->externalLibraryRegistry = $this->container->get('libraries.registry');
 
     $this->container->set('stream_wrapper.php_library_files', new TestPhpLibraryFilesStream());
   }
diff --git a/tests/src/Kernel/ExternalLibraryKernelTestBase.php b/tests/src/Kernel/ExternalLibraryKernelTestBase.php
index 7a6b13f8d3ed71fcaa6ed53b0b4c00f33902fd96..a23e88756af7f617fe81097548ba3bfcd76e5527 100644
--- a/tests/src/Kernel/ExternalLibraryKernelTestBase.php
+++ b/tests/src/Kernel/ExternalLibraryKernelTestBase.php
@@ -7,16 +7,19 @@
 
 namespace Drupal\Tests\libraries\Kernel;
 
-use Drupal\Component\FileCache\ApcuFileCacheBackend;
-use Drupal\Component\FileCache\FileCache;
-use Drupal\Component\FileCache\FileCacheFactory;
-use Drupal\KernelTests\KernelTestBase as CoreKernelTestBase;
-use Drupal\Core\Site\Settings;
+use Drupal\KernelTests\KernelTestBase;
 
 /**
  * Provides an improved version of the core kernel test base class.
  */
-abstract class ExternalLibraryKernelTestBase extends CoreKernelTestBase {
+abstract class ExternalLibraryKernelTestBase extends KernelTestBase {
+
+  /**
+   * The external library registry.
+   *
+   * @var \Drupal\libraries\ExternalLibrary\Registry\ExternalLibraryRegistryInterface
+   */
+  protected $externalLibraryRegistry;
 
   /**
    * The absolute path to the Libraries API module.
@@ -31,6 +34,8 @@ abstract class ExternalLibraryKernelTestBase extends CoreKernelTestBase {
   protected function setUp() {
     parent::setUp();
 
+    $this->externalLibraryRegistry = $this->container->get('libraries.registry');
+
     /** @var \Drupal\Core\Extension\ModuleHandlerInterface $module_handler */
     $root = $this->container->get('app.root');
     $module_handler = $this->container->get('module_handler');