diff -u b/src/Context/FieldResolver.php b/src/Context/FieldResolver.php
--- b/src/Context/FieldResolver.php
+++ b/src/Context/FieldResolver.php
@@ -90,11 +90,6 @@
     if (empty($external_field_name)) {
       throw new BadRequestHttpException('No field name was provided for the filter.');
     }
-    // Right now we are exposing all the fields with the name they have in
-    // the Drupal backend. But this may change in the future.
-    if (strpos($external_field_name, '.') === FALSE) {
-      return $resource_type->getInternalName($external_field_name);
-    }
     // Turns 'uid.categories.name' into
     // 'uid.entity.field_category.entity.name'. This may be too simple, but it
     // works for the time being.
reverted:
--- b/tests/src/Functional/comment/JsonApiFunctionalCommentTest.php
+++ /dev/null
@@ -1,30 +0,0 @@
-<?php
-
-namespace Drupal\Tests\jsonapi\Functional\comment;
-
-use Drupal\Component\Serialization\Json;
-
-/**
- * Test multi-level includes of jsonapi on comment's entity_id.
- *
- * The comment's entity_id is overwrited by bundle, the test's main purpose is
- * to test if multi-level includes of jsonapi work well on comment when comment
- * not belong to node.
- *
- * @group jsonapi
- */
-class JsonApiFunctionalCommentTest extends JsonApiFunctionalCommentTestBase {
-
-  /**
-   * Tests reading comment.
-   */
-  public function testReadComment() {
-    $values = ['field_my_user' => ['target_id' => $this->user->id()]];
-    $term = $this->createTerm($this->vocabulary, $values);
-    $comment = $this->createComment($term, 'field_my_comment', 'This is the comment_term body');
-    $output = Json::decode($this->drupalGet('/jsonapi/comment/comment_term/' . $comment->uuid(), ['query' => ['include' => 'entity_id,entity_id.field_my_user']]));
-    $this->assertEquals($term->uuid(), $output['included'][0]['attributes']['uuid']);
-    $this->assertEquals($this->user->uuid(), $output['included'][1]['attributes']['uuid']);
-  }
-
-}
reverted:
--- b/tests/src/Functional/comment/JsonApiFunctionalCommentTestBase.php
+++ /dev/null
@@ -1,178 +0,0 @@
-<?php
-
-namespace Drupal\Tests\jsonapi\Functional\comment;
-
-use Drupal\comment\Entity\Comment;
-use Drupal\comment\Entity\CommentType;
-use Drupal\Core\Entity\EntityInterface;
-use Drupal\Core\Field\FieldStorageDefinitionInterface;
-use Drupal\Core\Url;
-use Drupal\field\Entity\FieldConfig;
-use Drupal\field\Entity\FieldStorageConfig;
-use Drupal\field\Tests\EntityReference\EntityReferenceTestTrait;
-use Drupal\Tests\BrowserTestBase;
-use Drupal\Tests\taxonomy\Functional\TaxonomyTestTrait;
-use Drupal\user\Entity\Role;
-use Drupal\user\RoleInterface;
-use GuzzleHttp\Exception\ClientException;
-use GuzzleHttp\Exception\ServerException;
-
-/**
- * Provides helper methods for the JSON API module's functional tests.
- */
-abstract class JsonApiFunctionalCommentTestBase extends BrowserTestBase {
-
-  use EntityReferenceTestTrait;
-  use TaxonomyTestTrait;
-
-  public static $modules = [
-    'jsonapi',
-    'serialization',
-    'taxonomy',
-    'comment',
-  ];
-
-  /**
-   * User for testing.
-   *
-   * @var \Drupal\user\Entity\User
-   */
-  protected $user;
-
-  /**
-   * Vocabulary for testing.
-   *
-   * @var \Drupal\taxonomy\Entity\Vocabulary
-   */
-  protected $vocabulary;
-
-  /**
-   * HTTP client for test.
-   *
-   * @var \GuzzleHttp\ClientInterface
-   */
-  protected $httpClient;
-
-  /**
-   * {@inheritdoc}
-   */
-  protected function setUp() {
-    parent::setUp();
-
-    // Set up a HTTP client that accepts relative URLs.
-    $this->httpClient = $this->container->get('http_client_factory')
-      ->fromOptions(['base_uri' => $this->baseUrl]);
-
-    $this->vocabulary = $this->createVocabulary();
-
-    $this->createEntityReferenceField(
-      'taxonomy_term',
-      $this->vocabulary->id(),
-      'field_my_user',
-      'field_my_user',
-      'user',
-      'default',
-      [
-        'auto_create' => TRUE,
-      ],
-      FieldStorageDefinitionInterface::CARDINALITY_UNLIMITED
-    );
-    $commentTerm = CommentType::create([
-      'id' => 'comment_term',
-      'label' => 'comment term',
-      'description' => 'This is the comment bundle for taxonomy term.',
-      'target_entity_type_id' => 'taxonomy_term',
-    ]);
-    $commentTerm->save();
-
-    // Create a comment field on tags.
-    $fieldStorageTagsComment = FieldStorageConfig::create([
-      'entity_type' => 'taxonomy_term',
-      'field_name' => 'field_my_comment',
-      'type' => 'comment',
-      'settings' => [
-        'comment_type' => 'comment_term',
-      ],
-    ]);
-    $fieldStorageTagsComment->save();
-    FieldConfig::create([
-      'field_storage' => $fieldStorageTagsComment,
-      'label' => $this->randomMachineName(),
-      'entity_type' => 'taxonomy_term',
-      'bundle' => $this->vocabulary->id(),
-    ])->save();
-
-    // Create a user.
-    $this->user = $this->drupalCreateUser([]);
-
-    $this->grantPermissions(Role::load(RoleInterface::ANONYMOUS_ID), [
-      'access user profiles',
-      'administer taxonomy',
-      'administer comments',
-    ]);
-
-    drupal_flush_all_caches();
-  }
-
-  /**
-   * Performs a HTTP request. Wraps the Guzzle HTTP client.
-   *
-   * Why wrap the Guzzle HTTP client? Because any error response is returned via
-   * an exception, which would make the tests unnecessarily complex to read.
-   *
-   * @param string $method
-   *   HTTP method.
-   * @param \Drupal\Core\Url $url
-   *   URL to request.
-   * @param array $request_options
-   *   Request options to apply.
-   *
-   * @see \GuzzleHttp\ClientInterface::request()
-   *
-   * @return \Psr\Http\Message\ResponseInterface
-   *   Response
-   */
-  protected function request($method, Url $url, array $request_options) {
-    try {
-      $response = $this->httpClient->request($method, $url->toString(), $request_options);
-    }
-    catch (ClientException $e) {
-      $response = $e->getResponse();
-    }
-    catch (ServerException $e) {
-      $response = $e->getResponse();
-    }
-
-    return $response;
-  }
-
-  /**
-   * Create a comment.
-   *
-   * @param \Drupal\Core\Entity\EntityInterface $entity
-   *   The entity where the comment create on.
-   * @param string $fieldName
-   *   The comment field name.
-   * @param string $body
-   *   The comment body.
-   *
-   * @return \Drupal\comment\Entity\Comment
-   *   Comment entity.
-   */
-  public function createComment(EntityInterface $entity, $fieldName, $body) {
-    $values = [
-      'entity_type' => 'taxonomy_term',
-      'entity_id' => $entity->id(),
-      'field_name' => $fieldName,
-      'uid' => 0,
-      'comment_type' => 'comment_term',
-      'subject' => 'My Awesome Comment',
-      'comment_body' => $body,
-      'status' => 1,
-    ];
-    $comment = Comment::create($values);
-    $comment->save();
-    return $comment;
-  }
-
-}
diff -u b/tests/src/Kernel/Context/FieldResolverTest.php b/tests/src/Kernel/Context/FieldResolverTest.php
--- b/tests/src/Kernel/Context/FieldResolverTest.php
+++ b/tests/src/Kernel/Context/FieldResolverTest.php
@@ -29,118 +29,26 @@
 
     $this->sut = \Drupal::service('jsonapi.field_resolver');
 
-    EntityTestBundle::create([
-      'id' => 'bundle1',
-    ])->save();
-    EntityTestBundle::create([
-      'id' => 'bundle2',
-    ])->save();
-    EntityTestBundle::create([
-      'id' => 'bundle3',
-    ])->save();
-
-    FieldStorageConfig::create([
-      'field_name' => 'field_test1',
-      'type' => 'string',
-      'entity_type' => 'entity_test_with_bundle',
-    ])->save();
-    FieldConfig::create([
-      'field_name' => 'field_test1',
-      'entity_type' => 'entity_test_with_bundle',
-      'bundle' => 'bundle1',
-    ])->save();
-
-    FieldStorageConfig::create([
-      'field_name' => 'field_test2',
-      'type' => 'string',
-      'entity_type' => 'entity_test_with_bundle',
-    ])->save();
-    FieldConfig::create([
-      'field_name' => 'field_test2',
-      'entity_type' => 'entity_test_with_bundle',
-      'bundle' => 'bundle1',
-    ])->save();
-
-    FieldStorageConfig::create([
-      'field_name' => 'field_test3',
-      'type' => 'string',
-      'entity_type' => 'entity_test_with_bundle',
-    ])->save();
-    FieldConfig::create([
-      'field_name' => 'field_test3',
-      'entity_type' => 'entity_test_with_bundle',
-      'bundle' => 'bundle2',
-    ])->save();
-    FieldConfig::create([
-      'field_name' => 'field_test3',
-      'entity_type' => 'entity_test_with_bundle',
-      'bundle' => 'bundle3',
-    ])->save();
+    $this->makeBundle('bundle1');
+    $this->makeBundle('bundle2');
+    $this->makeBundle('bundle3');
+
+    $this->makeField('string', 'field_test1', 'entity_test_with_bundle', ['bundle1']);
+    $this->makeField('string', 'field_test2', 'entity_test_with_bundle', ['bundle1']);
+    $this->makeField('string', 'field_test3', 'entity_test_with_bundle', ['bundle2', 'bundle3']);
 
     // Provides entity reference fields.
-    FieldStorageConfig::create([
-      'field_name' => 'field_test_ref1',
-      'type' => 'entity_reference',
-      'settings' => [
-        'target_type' => 'entity_test_with_bundle',
-      ],
-      'entity_type' => 'entity_test_with_bundle',
-    ])->save();
-    FieldConfig::create([
-      'field_name' => 'field_test_ref1',
-      'entity_type' => 'entity_test_with_bundle',
-      'bundle' => 'bundle1',
-    ])->save();
-
-    FieldStorageConfig::create([
-      'field_name' => 'field_test_ref2',
-      'type' => 'entity_reference',
-      'settings' => [
-        'target_type' => 'entity_test_with_bundle',
+    $settings = ['target_type' => 'entity_test_with_bundle'];
+    $this->makeField('entity_reference', 'field_test_ref1', 'entity_test_with_bundle', ['bundle1'], $settings, [
+      'handler_settings' => [
+        'target_bundles' => ['bundle2', 'bundle3'],
       ],
-      'entity_type' => 'entity_test_with_bundle',
-    ])->save();
-    FieldConfig::create([
-      'field_name' => 'field_test_ref2',
-      'entity_type' => 'entity_test_with_bundle',
-      'bundle' => 'bundle1',
-    ])->save();
-
-    FieldStorageConfig::create([
-      'field_name' => 'field_test_ref3',
-      'type' => 'entity_reference',
-      'settings' => [
-        'target_type' => 'entity_test_with_bundle',
-      ],
-      'entity_type' => 'entity_test_with_bundle',
-    ])->save();
-    FieldConfig::create([
-      'field_name' => 'field_test_ref3',
-      'entity_type' => 'entity_test_with_bundle',
-      'bundle' => 'bundle2',
-    ])->save();
-    FieldConfig::create([
-      'field_name' => 'field_test_ref3',
-      'entity_type' => 'entity_test_with_bundle',
-      'bundle' => 'bundle3',
-    ])->save();
+    ]);
+    $this->makeField('entity_reference', 'field_test_ref2', 'entity_test_with_bundle', ['bundle1'], $settings);
+    $this->makeField('entity_reference', 'field_test_ref3', 'entity_test_with_bundle', ['bundle2', 'bundle3'], $settings);
 
     // Add a field with multiple properties.
-    FieldStorageConfig::create([
-      'field_name' => 'field_test_text',
-      'type' => 'text',
-      'entity_type' => 'entity_test_with_bundle',
-    ])->save();
-    FieldConfig::create([
-      'field_name' => 'field_test_text',
-      'entity_type' => 'entity_test_with_bundle',
-      'bundle' => 'bundle1',
-    ])->save();
-    FieldConfig::create([
-      'field_name' => 'field_test_text',
-      'entity_type' => 'entity_test_with_bundle',
-      'bundle' => 'bundle2',
-    ])->save();
+    $this->makeField('text', 'field_test_text', 'entity_test_with_bundle', ['bundle1', 'bundle2']);
   }
 
   /**
@@ -150,39 +58,79 @@
     $entity_type_id = 'entity_test_with_bundle';
     $bundle = 'bundle1';
 
-    $this->assertEquals('field_test1', $this->sut->resolveInternal($entity_type_id, $bundle, 'field_test1'));
-    $this->assertEquals('field_test2', $this->sut->resolveInternal($entity_type_id, $bundle, 'field_test2'));
-
-    $this->assertEquals('field_test_ref1.entity.field_test1', $this->sut->resolveInternal($entity_type_id, $bundle, 'field_test_ref1.field_test1'));
-    $this->assertEquals('field_test_ref1.entity.field_test2', $this->sut->resolveInternal($entity_type_id, $bundle, 'field_test_ref1.field_test2'));
-    $this->assertEquals('field_test_ref2.entity.field_test1', $this->sut->resolveInternal($entity_type_id, $bundle, 'field_test_ref2.field_test1'));
-    $this->assertEquals('field_test_ref2.entity.field_test2', $this->sut->resolveInternal($entity_type_id, $bundle, 'field_test_ref2.field_test2'));
-
-    $this->assertEquals('field_test_ref1.entity.field_test_text', $this->sut->resolveInternal($entity_type_id, $bundle, 'field_test_ref1.field_test_text'));
-    $this->assertEquals('field_test_ref1.entity.field_test_text.value', $this->sut->resolveInternal($entity_type_id, $bundle, 'field_test_ref1.field_test_text.value'));
-    $this->assertEquals('field_test_ref1.entity.field_test_text.format', $this->sut->resolveInternal($entity_type_id, $bundle, 'field_test_ref1.field_test_text.format'));
-    $this->assertEquals('field_test_ref2.entity.field_test_text', $this->sut->resolveInternal($entity_type_id, $bundle, 'field_test_ref2.field_test_text'));
-    $this->assertEquals('field_test_ref2.entity.field_test_text.value', $this->sut->resolveInternal($entity_type_id, $bundle, 'field_test_ref2.field_test_text.value'));
-    $this->assertEquals('field_test_ref2.entity.field_test_text.format', $this->sut->resolveInternal($entity_type_id, $bundle, 'field_test_ref2.field_test_text.format'));
-
-    /*$this->assertEquals('field_test3', $this->sut->resolveInternal($entity_type_id, $bundle, 'field_test3'));
-    $this->assertEquals('field_test_ref3.entity.field_test1', $this->sut->resolveInternal($entity_type_id, $bundle, 'field_test_ref3.field_test1'));
-    $this->assertEquals('field_test_ref3.entity.field_test2', $this->sut->resolveInternal($entity_type_id, $bundle, 'field_test_ref3.field_test2'));
-    */
+    $cases = [
+      ['field_test1', 'field_test1'],
+      ['field_test2', 'field_test2'],
+
+      ['field_test_ref2.entity.field_test1', 'field_test_ref2.field_test1'],
+      ['field_test_ref2.entity.field_test2', 'field_test_ref2.field_test2'],
+
+      ['field_test_ref1.entity.field_test_text', 'field_test_ref1.field_test_text'],
+      ['field_test_ref1.entity.field_test_text.value', 'field_test_ref1.field_test_text.value'],
+      ['field_test_ref1.entity.field_test_text.format', 'field_test_ref1.field_test_text.format'],
+      ['field_test_ref2.entity.field_test_text', 'field_test_ref2.field_test_text'],
+      ['field_test_ref2.entity.field_test_text.value', 'field_test_ref2.field_test_text.value'],
+      ['field_test_ref2.entity.field_test_text.format', 'field_test_ref2.field_test_text.format'],
+    ];
+
+    foreach ($cases as list($expect, $external_path)) {
+      $this->assertEquals($expect, $this->sut->resolveInternal($entity_type_id, $bundle, $external_path));
+    }
   }
 
   /**
    * Expects an error when an invalid field is provided.
    *
    * @covers ::resolveInternal
+   * @dataProvider resolveInternalErrorProvider
    *
    * @expectedException \Symfony\Component\HttpKernel\Exception\BadRequestHttpException
    */
-  public function testResolveInternalError() {
-    $original = 'host.fail!!.deep';
-    $not_expected = 'host.entity.fail!!.entity.deep';
+  public function testResolveInternalError($entity_type, $bundle, $external_path) {
+    $this->sut->resolveInternal($entity_type, $bundle, $external_path);
+  }
+
+  public function resolveInternalErrorProvider() {
+    return [
+      // Should fail because none of these bundles have these fields.
+      ['entity_test_with_bundle', 'bundle1', 'host.fail!!.deep'],
+      ['entity_test_with_bundle', 'bundle2', 'field_test_ref2'],
+      ['entity_test_with_bundle', 'bundle1', 'field_test_ref3'],
+      // Should fail because the nested field don't exist on the targeted resources.
+      ['entity_test_with_bundle', 'bundle1', 'field_test_ref1.field_test1'],
+      ['entity_test_with_bundle', 'bundle1', 'field_test_ref1.field_test2'],
+      ['entity_test_with_bundle', 'bundle1', 'field_test_ref1.field_test_ref1'],
+      ['entity_test_with_bundle', 'bundle1', 'field_test_ref1.field_test_ref2'],
+    ];
+  }
+
+  /**
+   * Create a simple bundle.
+   */
+  protected function makeBundle($name) {
+    EntityTestBundle::create([
+      'id' => $name,
+    ])->save();
+  }
 
-    $this->assertEquals($not_expected, $this->sut->resolveInternal('entity_test_with_bundle', 'bundle1', $original));
+  protected function makeField($type, $name, $entity_type, $bundles, $storage_settings = [], $config_settings = []) {
+    $storage_config = [
+      'field_name' => $name,
+      'type' => $type,
+      'entity_type' => $entity_type,
+      'settings' => $storage_settings,
+    ];
+
+    FieldStorageConfig::create($storage_config)->save();
+
+    foreach ($bundles as $bundle) {
+      FieldConfig::create([
+        'field_name' => $name,
+        'entity_type' => $entity_type,
+        'bundle' => $bundle,
+        'settings' => $config_settings,
+      ])->save();
+    }
   }
 
 }