reverted:
--- b/core/modules/file/src/Plugin/migrate/process/FileCopy.php
+++ /dev/null
@@ -1,207 +0,0 @@
-<?php
-
-namespace Drupal\file\Plugin\migrate\process;
-
-use Drupal\Core\File\FileSystemInterface;
-use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
-use Drupal\Core\StreamWrapper\LocalStream;
-use Drupal\Core\StreamWrapper\StreamWrapperManagerInterface;
-use Drupal\migrate\MigrateException;
-use Drupal\migrate\MigrateExecutableInterface;
-use Drupal\migrate\ProcessPluginBase;
-use Drupal\migrate\Row;
-use Symfony\Component\DependencyInjection\ContainerInterface;
-
-/**
- * Copy a file from one place into another.
- *
- * @MigrateProcessPlugin(
- *   id = "file_copy"
- * )
- */
-class FileCopy extends ProcessPluginBase implements ContainerFactoryPluginInterface {
-
-  /**
-   * The stream wrapper manager service.
-   *
-   * @var \Drupal\Core\StreamWrapper\StreamWrapperManagerInterface
-   */
-  protected $streamWrapperManager;
-
-  /**
-   * The file system service.
-   *
-   * @var \Drupal\Core\File\FileSystemInterface
-   */
-  protected $fileSystem;
-
-  /**
-   * Constructs a file_copy process plugin.
-   *
-   * @param array $configuration
-   *   The plugin configuration.
-   * @param string $plugin_id
-   *   The plugin ID.
-   * @param mixed $plugin_definition
-   *   The plugin definition.
-   * @param \Drupal\Core\StreamWrapper\StreamWrapperManagerInterface $stream_wrappers
-   *   The stream wrapper manager service.
-   * @param \Drupal\Core\File\FileSystemInterface $file_system
-   *   The file system service.
-   */
-  public function __construct(array $configuration, $plugin_id, array $plugin_definition, StreamWrapperManagerInterface $stream_wrappers, FileSystemInterface $file_system) {
-    $configuration += array(
-      'move' => FALSE,
-      'rename' => FALSE,
-    );
-    parent::__construct($configuration, $plugin_id, $plugin_definition);
-    $this->streamWrapperManager = $stream_wrappers;
-    $this->fileSystem = $file_system;
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
-    return new static(
-      $configuration,
-      $plugin_id,
-      $plugin_definition,
-      $container->get('stream_wrapper_manager'),
-      $container->get('file_system')
-    );
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function transform($value, MigrateExecutableInterface $migrate_executable, Row $row, $destination_property) {
-    // If we're stubbing a file entity, return a uri of NULL so it will get
-    // stubbed by the general process.
-    if ($row->isStub()) {
-      return NULL;
-    }
-    list($source, $destination) = $value;
-
-    // Ensure the source file exists, if it's a local URI or path.
-    if ($this->isLocalUri($source) && !file_exists($source)) {
-      throw new MigrateException("File '$source' does not exist.");
-    }
-
-    // If the start and end file is exactly the same, there is nothing to do.
-    if ($this->isLocationUnchanged($source, $destination)) {
-      return $destination;
-    }
-
-    $replace = $this->getOverwriteMode();
-    // We attempt the copy first to avoid calling file_prepare_directory() any
-    // more than absolutely necessary.
-    if ($this->writeFile($source, $destination, $replace)) {
-      return $destination;
-    }
-    $dir = $this->getDirectory($destination);
-    if (!file_prepare_directory($dir, FILE_CREATE_DIRECTORY)) {
-      throw new MigrateException("Could not create directory '$dir'");
-    }
-    if ($this->writeFile($source, $destination, $replace)) {
-      return $destination;
-    }
-    throw new MigrateException("File $source could not be copied to $destination.");
-  }
-
-  /**
-   * Tries to move or copy a file.
-   *
-   * @param string $source
-   *   The source path or URI.
-   * @param string $destination
-   *   The destination path or URI.
-   * @param int $replace
-   *   (optional) FILE_EXISTS_REPLACE (default) or FILE_EXISTS_RENAME.
-   *
-   * @return bool
-   *   TRUE on success, FALSE on failure.
-   */
-  protected function writeFile($source, $destination, $replace = FILE_EXISTS_REPLACE) {
-    if ($this->configuration['move']) {
-      return (boolean) file_unmanaged_move($source, $destination, $replace);
-    }
-    $destination = file_destination($destination, $replace);
-    return @copy($source, $destination);
-  }
-
-  /**
-   * Determines how to handle file conflicts.
-   *
-   * @return int
-   *   Either FILE_EXISTS_REPLACE (default) or FILE_EXISTS_RENAME, depending
-   *   on the current configuration.
-   */
-  protected function getOverwriteMode() {
-    if (!empty($this->configuration['rename'])) {
-      return FILE_EXISTS_RENAME;
-    }
-    return FILE_EXISTS_REPLACE;
-  }
-
-  /**
-   * Returns the directory component of a URI or path.
-   *
-   * For URIs like public://foo.txt, the full physical path of public://
-   * will be returned, since a scheme by itself will trip up certain file
-   * API functions (such as file_prepare_directory()).
-   *
-   * @param string $uri
-   *   The URI or path.
-   *
-   * @return string|false
-   *   The directory component of the path or URI, or FALSE if it could not
-   *   be determined.
-   */
-  protected function getDirectory($uri) {
-    $dir = $this->fileSystem->dirname($uri);
-    if (substr($dir, -3) == '://') {
-      return $this->fileSystem->realpath($dir);
-    }
-    return $dir;
-  }
-
-  /**
-   * Determines if the source and destination URIs represent identical paths.
-   *
-   * If either URI is a remote stream, will return FALSE.
-   *
-   * @param string $source
-   *   The source URI.
-   * @param string $destination
-   *   The destination URI.
-   *
-   * @return bool
-   *   TRUE if the source and destination URIs refer to the same physical path,
-   *   otherwise FALSE.
-   */
-  protected function isLocationUnchanged($source, $destination) {
-    if ($this->isLocalUri($source) && $this->isLocalUri($destination)) {
-      return $this->fileSystem->realpath($source) === $this->fileSystem->realpath($destination);
-    }
-    return FALSE;
-  }
-
-  /**
-   * Determines if the given URI or path is considered local.
-   *
-   * A URI or path is considered local if it either has no scheme component,
-   * or the scheme is implemented by a stream wrapper which extends
-   * \Drupal\Core\StreamWrapper\LocalStream.
-   *
-   * @param string $uri
-   *   The URI or path to test.
-   *
-   * @return bool
-   */
-  protected function isLocalUri($uri) {
-    $scheme = $this->fileSystem->uriScheme($uri);
-    return $scheme === FALSE || $this->streamWrapperManager->getViaScheme($scheme) instanceof LocalStream;
-  }
-
-}
reverted:
--- b/core/modules/file/src/Plugin/migrate/process/UrlEncode.php
+++ /dev/null
@@ -1,36 +0,0 @@
-<?php
-
-namespace Drupal\file\Plugin\migrate\process;
-
-use Drupal\migrate\MigrateExecutableInterface;
-use Drupal\migrate\ProcessPluginBase;
-use Drupal\migrate\Row;
-
-/**
- * Apply urlencoding to a URI.
- *
- * @MigrateProcessPlugin(
- *   id = "urlencode"
- * )
- */
-class UrlEncode extends ProcessPluginBase {
-
-  /**
-   * {@inheritdoc}
-   */
-  public function transform($value, MigrateExecutableInterface $migrate_executable, Row $row, $destination_property) {
-    // Only apply to a full URL.
-    if (strpos($value, '://') > 0) {
-      $components = explode('/', $value);
-      foreach ($components as $key => $component) {
-        // urlencode() would convert spaces to + signs.
-        $components[$key] = rawurlencode($component);
-      }
-      $value = implode('/', $components);
-      // Do not encode URL syntax characters.
-      $value = str_replace(['%3A', '%3F', '%26'], [':', '?', '&'], $value);
-    }
-    return $value;
-  }
-
-}
diff -u b/core/modules/file/tests/src/Kernel/Migrate/CopyFileProcessPluginTest.php b/core/modules/file/tests/src/Kernel/Migrate/CopyFileProcessPluginTest.php
--- b/core/modules/file/tests/src/Kernel/Migrate/CopyFileProcessPluginTest.php
+++ b/core/modules/file/tests/src/Kernel/Migrate/CopyFileProcessPluginTest.php
@@ -3,7 +3,7 @@
 namespace Drupal\Tests\file\Kernel\Migrate;
 
 use Drupal\Core\StreamWrapper\StreamWrapperInterface;
-use Drupal\file\Plugin\migrate\process\FileCopy;
+use Drupal\migrate\Plugin\migrate\process\FileCopy;
 use Drupal\migrate\MigrateExecutableInterface;
 use Drupal\migrate\Row;
 use Drupal\KernelTests\KernelTestBase;
diff -u b/core/modules/file/tests/src/Unit/Plugin/migrate/process/UrlEncodeTest.php b/core/modules/file/tests/src/Unit/Plugin/migrate/process/UrlEncodeTest.php
--- b/core/modules/file/tests/src/Unit/Plugin/migrate/process/UrlEncodeTest.php
+++ b/core/modules/file/tests/src/Unit/Plugin/migrate/process/UrlEncodeTest.php
@@ -2,14 +2,14 @@
 
 namespace Drupal\Tests\file\Unit\Plugin\migrate\process;
 
-use Drupal\file\Plugin\migrate\process\UrlEncode;
+use Drupal\migrate\Plugin\migrate\process\UrlEncode;
 use Drupal\migrate\MigrateExecutable;
 use Drupal\migrate\MigrateMessage;
 use Drupal\migrate\Row;
 use Drupal\Tests\migrate\Unit\MigrateTestCase;
 
 /**
- * @coversDefaultClass \Drupal\file\Plugin\migrate\process\UrlEncode
+ * @coversDefaultClass \Drupal\migrate\Plugin\migrate\process\UrlEncode
  * @group file
  */
 class UrlEncodeTest extends MigrateTestCase {
only in patch2:
unchanged:
--- /dev/null
+++ b/core/modules/migrate/src/Plugin/migrate/process/FileCopy.php
@@ -0,0 +1,207 @@
+<?php
+
+namespace Drupal\migrate\Plugin\migrate\process;
+
+use Drupal\Core\File\FileSystemInterface;
+use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
+use Drupal\Core\StreamWrapper\LocalStream;
+use Drupal\Core\StreamWrapper\StreamWrapperManagerInterface;
+use Drupal\migrate\MigrateExecutableInterface;
+use Drupal\migrate\MigrateSkipProcessException;
+use Drupal\migrate\ProcessPluginBase;
+use Drupal\migrate\Row;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+
+/**
+ * Copy a file from one place into another.
+ *
+ * @MigrateProcessPlugin(
+ *   id = "file_copy"
+ * )
+ */
+class FileCopy extends ProcessPluginBase implements ContainerFactoryPluginInterface {
+
+  /**
+   * The stream wrapper manager service.
+   *
+   * @var \Drupal\Core\StreamWrapper\StreamWrapperManagerInterface
+   */
+  protected $streamWrapperManager;
+
+  /**
+   * The file system service.
+   *
+   * @var \Drupal\Core\File\FileSystemInterface
+   */
+  protected $fileSystem;
+
+  /**
+   * Constructs a file_copy process plugin.
+   *
+   * @param array $configuration
+   *   The plugin configuration.
+   * @param string $plugin_id
+   *   The plugin ID.
+   * @param mixed $plugin_definition
+   *   The plugin definition.
+   * @param \Drupal\Core\StreamWrapper\StreamWrapperManagerInterface $stream_wrappers
+   *   The stream wrapper manager service.
+   * @param \Drupal\Core\File\FileSystemInterface $file_system
+   *   The file system service.
+   */
+  public function __construct(array $configuration, $plugin_id, array $plugin_definition, StreamWrapperManagerInterface $stream_wrappers, FileSystemInterface $file_system) {
+    $configuration += array(
+      'move' => FALSE,
+      'rename' => FALSE,
+    );
+    parent::__construct($configuration, $plugin_id, $plugin_definition);
+    $this->streamWrapperManager = $stream_wrappers;
+    $this->fileSystem = $file_system;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
+    return new static(
+      $configuration,
+      $plugin_id,
+      $plugin_definition,
+      $container->get('stream_wrapper_manager'),
+      $container->get('file_system')
+    );
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function transform($value, MigrateExecutableInterface $migrate_executable, Row $row, $destination_property) {
+    // If we're stubbing a file entity, return a uri of NULL so it will get
+    // stubbed by the general process.
+    if ($row->isStub()) {
+      return NULL;
+    }
+    list($source, $destination) = $value;
+
+    // Ensure the source file exists, if it's a local URI or path.
+    if ($this->isLocalUri($source) && !file_exists($source)) {
+      throw new MigrateSkipProcessException("File '$source' does not exist.");
+    }
+
+    // If the start and end file is exactly the same, there is nothing to do.
+    if ($this->isLocationUnchanged($source, $destination)) {
+      return $destination;
+    }
+
+    $replace = $this->getOverwriteMode();
+    // We attempt the copy first to avoid calling file_prepare_directory() any
+    // more than absolutely necessary.
+    if ($this->writeFile($source, $destination, $replace)) {
+      return $destination;
+    }
+    $dir = $this->getDirectory($destination);
+    if (!file_prepare_directory($dir, FILE_CREATE_DIRECTORY)) {
+      throw new MigrateSkipProcessException("Could not create directory '$dir'");
+    }
+    if ($this->writeFile($source, $destination, $replace)) {
+      return $destination;
+    }
+    throw new MigrateSkipProcessException("File $source could not be copied to $destination.");
+  }
+
+  /**
+   * Tries to move or copy a file.
+   *
+   * @param string $source
+   *   The source path or URI.
+   * @param string $destination
+   *   The destination path or URI.
+   * @param int $replace
+   *   (optional) FILE_EXISTS_REPLACE (default) or FILE_EXISTS_RENAME.
+   *
+   * @return bool
+   *   TRUE on success, FALSE on failure.
+   */
+  protected function writeFile($source, $destination, $replace = FILE_EXISTS_REPLACE) {
+    if ($this->configuration['move']) {
+      return (boolean) file_unmanaged_move($source, $destination, $replace);
+    }
+    $destination = file_destination($destination, $replace);
+    return @copy($source, $destination);
+  }
+
+  /**
+   * Determines how to handle file conflicts.
+   *
+   * @return int
+   *   Either FILE_EXISTS_REPLACE (default) or FILE_EXISTS_RENAME, depending
+   *   on the current configuration.
+   */
+  protected function getOverwriteMode() {
+    if (!empty($this->configuration['rename'])) {
+      return FILE_EXISTS_RENAME;
+    }
+    return FILE_EXISTS_REPLACE;
+  }
+
+  /**
+   * Returns the directory component of a URI or path.
+   *
+   * For URIs like public://foo.txt, the full physical path of public://
+   * will be returned, since a scheme by itself will trip up certain file
+   * API functions (such as file_prepare_directory()).
+   *
+   * @param string $uri
+   *   The URI or path.
+   *
+   * @return string|false
+   *   The directory component of the path or URI, or FALSE if it could not
+   *   be determined.
+   */
+  protected function getDirectory($uri) {
+    $dir = $this->fileSystem->dirname($uri);
+    if (substr($dir, -3) == '://') {
+      return $this->fileSystem->realpath($dir);
+    }
+    return $dir;
+  }
+
+  /**
+   * Determines if the source and destination URIs represent identical paths.
+   *
+   * If either URI is a remote stream, will return FALSE.
+   *
+   * @param string $source
+   *   The source URI.
+   * @param string $destination
+   *   The destination URI.
+   *
+   * @return bool
+   *   TRUE if the source and destination URIs refer to the same physical path,
+   *   otherwise FALSE.
+   */
+  protected function isLocationUnchanged($source, $destination) {
+    if ($this->isLocalUri($source) && $this->isLocalUri($destination)) {
+      return $this->fileSystem->realpath($source) === $this->fileSystem->realpath($destination);
+    }
+    return FALSE;
+  }
+
+  /**
+   * Determines if the given URI or path is considered local.
+   *
+   * A URI or path is considered local if it either has no scheme component,
+   * or the scheme is implemented by a stream wrapper which extends
+   * \Drupal\Core\StreamWrapper\LocalStream.
+   *
+   * @param string $uri
+   *   The URI or path to test.
+   *
+   * @return bool
+   */
+  protected function isLocalUri($uri) {
+    $scheme = $this->fileSystem->uriScheme($uri);
+    return $scheme === FALSE || $this->streamWrapperManager->getViaScheme($scheme) instanceof LocalStream;
+  }
+
+}
only in patch2:
unchanged:
--- /dev/null
+++ b/core/modules/migrate/src/Plugin/migrate/process/UrlEncode.php
@@ -0,0 +1,39 @@
+<?php
+
+namespace Drupal\migrate\Plugin\migrate\process;
+
+use Drupal\migrate\MigrateExecutableInterface;
+use Drupal\migrate\ProcessPluginBase;
+use Drupal\migrate\Row;
+
+/**
+ * Apply urlencoding to a URI.
+ *
+ * This is needed when the URI is to be opened by a later migration stage, and
+ * the source URI value is not already encoded.
+ *
+ * @MigrateProcessPlugin(
+ *   id = "urlencode"
+ * )
+ */
+class UrlEncode extends ProcessPluginBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function transform($value, MigrateExecutableInterface $migrate_executable, Row $row, $destination_property) {
+    // Only apply to a full URL.
+    if (strpos($value, '://') > 0) {
+      $components = explode('/', $value);
+      foreach ($components as $key => $component) {
+        // urlencode() would convert spaces to + signs.
+        $components[$key] = rawurlencode($component);
+      }
+      $value = implode('/', $components);
+      // Do not encode URL syntax characters.
+      $value = str_replace(['%3A', '%3F', '%26'], [':', '?', '&'], $value);
+    }
+    return $value;
+  }
+
+}
only in patch2:
unchanged:
--- /dev/null
+++ b/core/modules/migrate/tests/src/Unit/process/CopyFileTest.php
@@ -0,0 +1,148 @@
+<?php
+
+namespace Drupal\Tests\migrate\Kernel\Migrate;
+
+use Drupal\Core\StreamWrapper\StreamWrapperInterface;
+use Drupal\migrate\Plugin\migrate\process\FileCopy;
+use Drupal\migrate\MigrateExecutableInterface;
+use Drupal\migrate\Row;
+use Drupal\KernelTests\KernelTestBase;
+
+/**
+ * Tests the copy_file process plugin.
+ *
+ * @group file
+ */
+class CopyFileTest extends KernelTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public static $modules = ['system'];
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp() {
+    parent::setUp();
+    $this->container->get('stream_wrapper_manager')->registerWrapper('public', 'Drupal\Core\StreamWrapper\PublicStream', StreamWrapperInterface::NORMAL);
+  }
+
+  /**
+   * Test successful imports/copies.
+   */
+  public function testSuccessfulCopies() {
+    foreach ($this->localFileDataCopyProvider() as $data) {
+      list($source_path, $destination_path, $expected) = $data;
+      $this->doImport($source_path, $destination_path);
+      $message = $expected ? sprintf('File %s exists', $destination_path) : sprintf('File %s does not exist', $destination_path);
+      $this->assertSame($expected, is_file($destination_path), $message);
+      // Make sure we didn't accidentally do a move.
+      $message = $expected ? sprintf('File %s exists', $source_path) : sprintf('File %s does not exist', $source_path);
+      $this->assertSame($expected, is_file($source_path), $message);
+    }
+  }
+
+  /**
+   * The data provider for testing the file destination.
+   *
+   * @return array
+   *   An array of file permutations to test.
+   */
+  protected function localFileDataCopyProvider() {
+    touch('/tmp/test-file.jpg');
+    return [
+      // Test a local to local copy.
+      [$this->root . '/core/modules/simpletest/files/image-test.jpg', 'public://file1.jpg', TRUE],
+      // Test a temporary file using an absolute path.
+      ['/tmp/test-file.jpg', 'temporary://test.jpg', TRUE],
+      // Test a temporary file using a relative path.
+      ['/tmp/test-file.jpg', 'temporary://core/modules/simpletest/files/test.jpg', TRUE],
+    ];
+  }
+
+  /**
+   * Test successful moves.
+   */
+  public function testSuccessfulMoves() {
+    foreach ($this->localFileDataMoveProvider() as $data) {
+      list($source_path, $destination_path, $expected) = $data;
+      $this->doImport($source_path, $destination_path, ['move' => TRUE]);
+      $message = $expected ? sprintf('File %s exists', $destination_path) : sprintf('File %s does not exist', $destination_path);
+      $this->assertSame($expected, is_file($destination_path), $message);
+      $message = $expected ? sprintf('File %s does not exist', $source_path) : sprintf('File %s exists', $source_path);
+      $this->assertSame($expected, !is_file($source_path), $message);
+    }
+  }
+
+  /**
+   * The data provider for testing the file destination.
+   *
+   * @return array
+   *   An array of file permutations to test.
+   */
+  protected function localFileDataMoveProvider() {
+    touch('/tmp/test-file.jpg');
+    touch('/tmp/test-file2.jpg');
+    $local_file = $this->root . '/sites/default/files/source_file.txt';
+    touch($local_file);
+    return [
+      // Test a local to local copy.
+      [$local_file, 'public://file1.jpg', TRUE],
+      // Test a temporary file using an absolute path.
+      ['/tmp/test-file.jpg', 'temporary://test.jpg', TRUE],
+      // Test a temporary file using a relative path.
+      ['/tmp/test-file2.jpg', 'temporary://core/modules/simpletest/files/test.jpg', TRUE],
+    ];
+  }
+
+  /**
+   * Test that non-existent files throw an exception.
+   *
+   * @expectedException \Drupal\migrate\MigrateException
+   *
+   * @expectedExceptionMessage File '/non/existent/file' does not exist
+   */
+  public function testNonExistentSourceFile() {
+    $source = '/non/existent/file';
+    $this->doImport($source, 'public://wontmatter.jpg');
+  }
+
+  /**
+   * Test the 'rename' overwrite mode.
+   */
+  public function testRenameFile() {
+    $source = 'temporary://baz.txt';
+    $destination = 'public://foo.txt';
+    $expected_destination = 'public://foo_0.txt';
+    touch($source);
+    touch($destination);
+    $this->doImport($source, $destination, ['rename' => TRUE]);
+    $this->assertFileExists($expected_destination);
+  }
+
+  /**
+   * Do an import using the destination.
+   *
+   * @param string $source_path
+   *   Source path to copy from.
+   * @param string $destination_path
+   *   The destination path to copy to.
+   * @param array $configuration
+   *   Process plugin configuration settings.
+   *
+   * @throws \Drupal\migrate\MigrateException
+   */
+  protected function doImport($source_path, $destination_path, $configuration = []) {
+    $this->plugin = FileCopy::create($this->container, $configuration, 'file_copy', []);
+    $executable = $this->prophesize(MigrateExecutableInterface::class)->reveal();
+    $row = new Row([], []);
+
+    $result = $this->plugin->transform([$source_path, $destination_path], $executable, $row, 'foobaz');
+
+    // The plugin should either throw an exception or return the destination
+    // path.
+    $this->assertSame($result, $destination_path);
+  }
+
+}
only in patch2:
unchanged:
--- /dev/null
+++ b/core/modules/migrate/tests/src/Unit/process/UrlEncodeTest.php
@@ -0,0 +1,59 @@
+<?php
+
+namespace Drupal\Tests\migrate\Unit\Plugin\migrate\process;
+
+use Drupal\migrate\Plugin\migrate\process\UrlEncode;
+use Drupal\migrate\MigrateExecutable;
+use Drupal\migrate\MigrateMessage;
+use Drupal\migrate\Row;
+use Drupal\Tests\migrate\Unit\MigrateTestCase;
+
+/**
+ * @coversDefaultClass \Drupal\migrate\Plugin\migrate\process\UrlEncode
+ * @group file
+ */
+class UrlEncodeTest extends MigrateTestCase {
+
+  protected $migrationConfiguration = [
+    'id' => 'test',
+  ];
+
+  /**
+   * Cover various encoding scenarios.
+   */
+  public function testUrls() {
+    $values = [
+      // A URL with no characters requiring encoding.
+      'http://example.com/normal_url.html' => 'http://example.com/normal_url.html',
+      // The definitive use case - encoding spaces in URLs.
+      'http://example.com/url with spaces.html' => 'http://example.com/url%20with%20spaces.html',
+      // Local filespecs should not be transformed, with or without spaces.
+      '/tmp/normal.txt' => '/tmp/normal.txt',
+      '/tmp/with spaces.txt' => '/tmp/with spaces.txt',
+      // Make sure URL characters (:, ?, &) are not encoded but others are.
+      'https://example.com/?a=b@c&d=e+f%' => 'https://example.com/?a%3Db%40c&d%3De%2Bf%25',
+    ];
+
+    foreach ($values as $input => $output) {
+      $this->assertEquals($output, $this->doTransform($input));
+    }
+  }
+
+  /**
+   * Perform the urlencode process plugin over the given value.
+   *
+   * @param string $value
+   *   Url to be encoded.
+   *
+   * @return string
+   *   Encoded url.
+   */
+  protected function doTransform($value) {
+    $executable = new MigrateExecutable($this->getMigration(), new MigrateMessage());
+    $row = new Row([], []);
+
+    return (new UrlEncode([], 'urlencode', []))
+      ->transform($value, $executable, $row, 'foobaz');
+  }
+
+}