diff --git a/entityreference_autocomplete.info b/entityreference_autocomplete.info
index d778524..d3bddab 100644
--- a/entityreference_autocomplete.info
+++ b/entityreference_autocomplete.info
@@ -1,5 +1,9 @@
 name = Entity Reference Autocomplete
 description = A Form API element type to reference arbitrary entities through an autocomplete textfield
 core = 7.x
+php = 5.3
 
-dependencies[] = entity
+autoload[tests/src][] = Drupal\Tests\entity_reference_autocomplete
+
+; Dependencies for running autotests.
+test_dependencies[] = autoload (>=7.x-1.3)
diff --git a/entityreference_autocomplete.module b/entityreference_autocomplete.module
index 645cebd..57d94f3 100644
--- a/entityreference_autocomplete.module
+++ b/entityreference_autocomplete.module
@@ -92,22 +92,94 @@ function entityreference_autocomplete_element_info() {
  *
  * @return string|bool
  *   The value to be placed in $element['#value'].
+ *
+ * @example
+ * The "#default_value" can be any one of:
+ *
+ * @code
+ * // A single entity ID.
+ * $element['#default_value'] = 1234;
+ *
+ * // An array of entity IDs.
+ * $element['#default_value'] = array(1234, 1235);
+ *
+ * // A single entity.
+ * $element['#default_value'] = node_load(1234);
+ *
+ * // An array of entities.
+ * $element['#default_value'] = array(node_load(1234), node_load(1235));
+ *
+ * // A single entity structure.
+ * $element['#default_value'] = array(
+ *   'entity_id' => 1234,
+ *   'entity_type' => 'node',
+ *   'entity_label' => 'Label',
+ *   'entity_bundle' => 'article',
+ * );
+ *
+ * // An array of entity structures.
+ * $element['#default_value'] = array(
+ *   array(
+ *     'entity_id' => 1234,
+ *     'entity_type' => 'node',
+ *     'entity_label' => 'Label 1',
+ *     'entity_bundle' => 'article',
+ *   ),
+ *   array(
+ *     'entity_id' => 1235,
+ *     'entity_type' => 'node',
+ *     'entity_label' => 'Label 2',
+ *     'entity_bundle' => 'article',
+ *   ),
+ * );
+ * @endcode
  */
 function entityreference_autocomplete_value_callback(array $element, $edit = FALSE) {
   // Just process the value when $edit comes as FALSE (no form submission).
   if (FALSE === $edit && !empty($element['#default_value'])) {
-    // If there are any default values, transform them into proper labels.
-    $labels = array();
+    $default_values = $element['#default_value'];
+    $entity_labels = array();
+
+    // Check that value is an entity ID or entity itself.
+    $is_value_acceptable = function ($value) {
+      return is_numeric($value) || is_object($value);
+    };
+
+    // Check that value is a list of "entityreference_autocomplete" structures.
+    $is_list_of_values = function ($value) {
+      return is_array($value) && isset($value['entity_id']) && is_numeric($value['entity_id']);
+    };
+
+    // Single entity ID or entity object.
+    if ($is_value_acceptable($default_values)) {
+      $default_values = array($default_values);
+    }
+    // Not an array - good bay!
+    elseif (!is_array($default_values)) {
+      return $default_values;
+    }
+    elseif ($is_list_of_values($default_values)) {
+      $default_values = array($default_values['entity_id']);
+    }
+
+    foreach ($default_values as $default_value) {
+      if ($is_list_of_values($default_value)) {
+        $default_value = $default_value['entity_id'];
+      }
 
-    foreach (is_array(reset($element['#default_value'])) ? $element['#default_value'] : array($element['#default_value']) as $value) {
-      $labels[] = entityreference_autocomplete_label_for_reference($value['entity_type'], $value['entity_id']);
+      if ($is_value_acceptable($default_value)) {
+        $entity_labels[] = entityreference_autocomplete_label_for_reference(
+          $element['#era_entity_type'],
+          $default_value
+        );
+      }
     }
 
-    $labels = array_filter($labels);
+    $entity_labels = array_filter($entity_labels);
 
     // This should never be reached, but if it's, return whatever default
     // value was specified.
-    return empty($labels) ? $element['#default_value'] : implode(', ', $labels);
+    return empty($entity_labels) ? $default_values : implode(', ', $entity_labels);
   }
 
   // The user submitted a value for the element. Return it as is.
@@ -187,7 +259,7 @@ function entityreference_autocomplete_validate_entityreference(array &$element,
       $query->entityCondition('entity_id', $matches[1]);
     }
     else {
-      $label_column = entityreference_autocomplete_resolve_entity_label_column($entity_type);
+      $label_column = entityreference_autocomplete_resolve_entity_label_column($entity_type, $entity_info);
       $query->propertyCondition($label_column, $entity_label);
     }
 
@@ -249,7 +321,7 @@ function entityreference_autocomplete_validate_entityreference(array &$element,
 
         // User doesn't have read (view) access to it, set same error as the one
         // for no matches, since we don't want to reveal that the entity exists.
-        if (!entity_access('view', $entity_type, $entity)) {
+        if (!entityreference_autocomplete_entity_access('view', $entity_type, $entity, $entity_info)) {
           form_error($element, t('There are no entities matching "%value"', array(
             '%value' => $entity_label,
           )));
@@ -283,33 +355,35 @@ function entityreference_autocomplete_validate_entityreference(array &$element,
  *
  * @param string $entity_type
  *   The type of the entity being referenced.
- * @param string|int $entity_id
+ * @param string|int|object $entity
  *   The ID of the Entity being referenced.
  * @param bool $quote_wrap
  *   Whether the label should be wrapped within quotes if it contains commas or
- *   quotes. defaults to TRUE.
+ *   quotes. Defaults to TRUE.
  *
  * @return string
  *   The assembled label for the reference.
  */
-function entityreference_autocomplete_label_for_reference($entity_type, $entity_id, $quote_wrap = TRUE) {
-  if ($entity_referenced = entity_load_single($entity_type, $entity_id)) {
-    $reference_label = entity_label($entity_type, $entity_referenced) . " ($entity_id)";
-
-    // Names containing commas, preceding or trailing spaces, or quotes, must be
-    // wrapped in quotes.
-    if (
-      $quote_wrap &&
-      (
-        strpos($reference_label, ',') !== FALSE ||
-        strpos($reference_label, '"') !== FALSE ||
-        trim($reference_label) !== $reference_label
-      )
-    ) {
-      $reference_label = '"' . str_replace('"', '""', $reference_label) . '"';
-    }
+function entityreference_autocomplete_label_for_reference($entity_type, $entity, $quote_wrap = TRUE) {
+  if (is_numeric($entity)) {
+    $entity = entity_load($entity_type, array($entity));
+    $entity = reset($entity);
+  }
+
+  if (!empty($entity)) {
+    list($entity_id) = entity_extract_ids($entity_type, $entity);
+
+    if (!empty($entity_id)) {
+      $label = entity_label($entity_type, $entity) . " ($entity_id)";
+
+      // Names containing commas, preceding or trailing spaces, or quotes,
+      // must be wrapped in quotes.
+      if ($quote_wrap && (strpos($label, ',') !== FALSE || strpos($label, '"') !== FALSE || trim($label) !== $label)) {
+        $label = '"' . str_replace('"', '""', $label) . '"';
+      }
 
-    return $reference_label;
+      return $label;
+    }
   }
 
   // No entity object loaded, so return NULL.
@@ -321,14 +395,19 @@ function entityreference_autocomplete_label_for_reference($entity_type, $entity_
  *
  * @param string $entity_type
  *   The entity type for which the column to use as label needs to be resolved.
+ * @param array $entity_info
+ *   Entity definition, returned by "entity_get_info($entity_type)".
  *
  * @return string
  *   The name of the column to use as the entity label for the passed entity.
  */
-function entityreference_autocomplete_resolve_entity_label_column($entity_type) {
-  $entity_info = entity_get_info($entity_type);
+function entityreference_autocomplete_resolve_entity_label_column($entity_type, array $entity_info = array()) {
   $label_column = FALSE;
 
+  if (empty($entity_info)) {
+    $entity_info = entity_get_info($entity_type);
+  }
+
   // Check if the entity has a label column defined.
   if (isset($entity_info['entity keys']['label'])) {
     $label_column = $entity_info['entity keys']['label'];
@@ -398,3 +477,41 @@ function entityreference_autocomplete_explode_tags($tags, $remove_escape_formatt
 
   return $typed_tags;
 }
+
+/**
+ * Determines whether the given user can perform actions on an entity.
+ *
+ * Currently this is replacement of "entity_access()" from "entity" module.
+ *
+ * @param string $op
+ *   The operation being performed. One of "view", "update", "create" or
+ *   "delete".
+ * @param string $entity_type
+ *   The type of entity to check for.
+ * @param object $entity
+ *   Optionally an entity to check access for. If no entity is given, it will
+ *   be determined whether access is allowed for all entities of the given type.
+ * @param array $entity_info
+ *   Entity definition, returned by "entity_get_info($entity_type)".
+ *
+ * @return bool
+ *   Whether access is allowed or not. If the entity type does not specify any
+ *   access information, TRUE is returned.
+ */
+function entityreference_autocomplete_entity_access($op, $entity_type, $entity = NULL, array $entity_info = array()) {
+  if (empty($entity_info)) {
+    $entity_info = entity_get_info($entity_type);
+  }
+
+  if (isset($entity_info['access callback'])) {
+    // Check an access for global user.
+    $account = NULL;
+
+    return $entity_info['access callback']($op, $entity, $account, $entity_type);
+  }
+
+  // The "access callback" property provided by "entity" module, but we are
+  // not going to be dependent from it just for using "entity_access()". Assume
+  // that access is allowed if no explicit checker for this is set.
+  return TRUE;
+}
diff --git a/includes/autocomplete_callback.inc b/includes/autocomplete_callback.inc
index baf4e87..865558a 100644
--- a/includes/autocomplete_callback.inc
+++ b/includes/autocomplete_callback.inc
@@ -64,7 +64,7 @@ function entityreference_autocomplete_autocomplete_callback($entity_type, $bundl
     }
 
     // Fetch the column to use as label.
-    $label_column = entityreference_autocomplete_resolve_entity_label_column($entity_type);
+    $label_column = entityreference_autocomplete_resolve_entity_label_column($entity_type, $entity_info);
     $query->propertyCondition($label_column, $last_label, 'CONTAINS');
 
     // Set property conditions, if any.
@@ -109,10 +109,10 @@ function entityreference_autocomplete_autocomplete_callback($entity_type, $bundl
       // Iterate through all entities retrieved and process the data to return
       // it as expected by Drupal javascript.
       foreach ($entities as $entity_id => $entity) {
-        if (entity_access('view', $entity_type, $entity)) {
+        if (entityreference_autocomplete_entity_access('view', $entity_type, $entity, $entity_info)) {
           // Get the labels for the key and for the option.
-          $option = entityreference_autocomplete_label_for_reference($entity_type, $entity_id, FALSE);
-          $key = entityreference_autocomplete_label_for_reference($entity_type, $entity_id);
+          $option = entityreference_autocomplete_label_for_reference($entity_type, $entity, FALSE);
+          $key = entityreference_autocomplete_label_for_reference($entity_type, $entity);
 
           // $prefix . $key is the value that will be set in the textfield in
           // the browser, whereas $option is the html that is shown to the user
diff --git a/tests/modules/entityreference_autocomplete_test/entityreference_autocomplete_test.info b/tests/modules/entityreference_autocomplete_test/entityreference_autocomplete_test.info
new file mode 100644
index 0000000..a92810b
--- /dev/null
+++ b/tests/modules/entityreference_autocomplete_test/entityreference_autocomplete_test.info
@@ -0,0 +1,5 @@
+name = Entity Reference Autocomplete (Test)
+hidden = TRUE
+core = 7.x
+
+dependencies[] = entityreference_autocomplete
diff --git a/tests/modules/entityreference_autocomplete_test/entityreference_autocomplete_test.module b/tests/modules/entityreference_autocomplete_test/entityreference_autocomplete_test.module
new file mode 100644
index 0000000..ed6d8a5
--- /dev/null
+++ b/tests/modules/entityreference_autocomplete_test/entityreference_autocomplete_test.module
@@ -0,0 +1,27 @@
+<?php
+
+/**
+ * @file
+ * Entity Reference Autocomplete (Test).
+ */
+
+/**
+ * {@inheritdoc}
+ *
+ * @internal
+ */
+function entityreference_autocomplete_test_form(array $form, array &$form_state) {
+  if (!array_key_exists('entity_type', $_SESSION) || !array_key_exists('default_value', $_SESSION)) {
+    throw new \RuntimeException('Test cannot be executed without value and entity ID.');
+  }
+
+  $form['entityreference'] = array(
+    '#type' => 'entityreference',
+    '#default_value' => $_SESSION['default_value'],
+    '#era_bundles' => isset($_SESSION['bundles']) ? $_SESSION['bundles'] : [],
+    '#era_entity_type' => $_SESSION['entity_type'],
+    '#era_cardinality' => isset($_SESSION['cardinality']) ? $_SESSION['cardinality'] : 1,
+  );
+
+  return $form;
+}
diff --git a/tests/src/BaseTest.inc b/tests/src/BaseTest.inc
new file mode 100644
index 0000000..24536c9
--- /dev/null
+++ b/tests/src/BaseTest.inc
@@ -0,0 +1,75 @@
+<?php
+
+namespace Drupal\Tests\entity_reference_autocomplete;
+
+/**
+ * Base fixture for "entityreference_autocomplete" tests.
+ */
+abstract class BaseTest extends \DrupalWebTestCase {
+
+  /**
+   * Description of the test.
+   */
+  const DESCRIPTION = '';
+
+  /**
+   * {@inheritdoc}
+   */
+  final public static function getInfo() {
+    $info = array();
+    $info['name'] = static::class;
+    $info['group'] = 'Entity';
+
+    if (!empty(static::DESCRIPTION)) {
+      $info['description'] = static::DESCRIPTION;
+    }
+
+    return $info;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp() {
+    parent::setUp(array('entityreference_autocomplete_test'));
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function tearDown() {
+    parent::tearDown();
+
+    unset(
+      $_SESSION['entity_type'],
+      $_SESSION['default_value'],
+      $_SESSION['cardinality'],
+      $_SESSION['bundles']
+    );
+  }
+
+  /**
+   * Build the form with "entityreference" field.
+   *
+   * @param string $entity_type
+   *   Entity type to reference.
+   * @param mixed $default_value
+   *   Default value for the reference field.
+   * @param int $cardinality
+   *   Number of allowed references per field.
+   * @param string[] $bundles
+   *   List of entity bundles for filtering.
+   *
+   * @see entityreference_autocomplete_test_form()
+   */
+  protected function buildForm($entity_type, $default_value, $cardinality = 1, array $bundles = []) {
+    $_SESSION['entity_type'] = $entity_type;
+    $_SESSION['default_value'] = $default_value;
+    $_SESSION['cardinality'] = $cardinality;
+    $_SESSION['bundles'] = $bundles;
+
+    $form = drupal_get_form('entityreference_autocomplete_test_form');
+    $this->drupalSetContent(drupal_render($form));
+  }
+
+}
diff --git a/tests/src/ValueCallbackTest.inc b/tests/src/ValueCallbackTest.inc
new file mode 100644
index 0000000..2d9f6a6
--- /dev/null
+++ b/tests/src/ValueCallbackTest.inc
@@ -0,0 +1,117 @@
+<?php
+
+namespace Drupal\Tests\entity_reference_autocomplete;
+
+/**
+ * {@inheritdoc}
+ */
+class ValueCallbackTest extends BaseTest {
+
+  /**
+   * {@inheritdoc}
+   */
+  const DESCRIPTION = 'Ensure that "#value_callback" from element definition works properly.';
+
+  /**
+   * Test acceptable values for element definition.
+   */
+  public function testAcceptableValues() {
+    $entity_type = 'user';
+
+    $entity = $this->drupalCreateUser();
+    list($entity_id) = entity_extract_ids($entity_type, $entity);
+
+    $entity2 = $this->drupalCreateUser();
+    list($entity_id2) = entity_extract_ids($entity_type, $entity2);
+
+    $structure = array(
+      'entity_id' => $entity_id,
+      'entity_type' => 'dummy',
+    );
+
+    $structure2 = array(
+      'entity_id' => $entity_id2,
+      'entity_type' => 'dummy',
+    );
+
+    // Test single-valued field.
+    foreach (array(
+      'Try single entity ID' => $entity_id,
+      'Try list of entity IDs' => array($entity_id),
+      'Try single structure' => $structure,
+      'Try an array of structures' => array($structure),
+      'Try single entity' => $entity,
+      'Try list of entities' => array($entity),
+    ) as $test_name => $default_value) {
+      $label = sprintf('%s (%s)', entity_label($entity_type, $entity), $entity_id);
+
+      $this->buildForm($entity_type, $default_value);
+      $this->assertFieldByName('entityreference', $label, $test_name);
+    }
+
+    // Test multivalued field.
+    foreach (array(
+      'Try list of entity IDs (2 values)' => array($entity_id, $entity_id2),
+      'Try an array of structures (2 values)' => array($structure, $structure2),
+      'Try list of entities (2 values)' => array($entity, $entity2),
+    ) as $test_name => $default_value) {
+      $label = sprintf(
+        '%s (%s), %s (%s)',
+        entity_label($entity_type, $entity),
+        $entity_id,
+        entity_label($entity_type, $entity2),
+        $entity_id2
+      );
+
+      $this->buildForm($entity_type, $default_value, 2);
+      $this->assertFieldByName('entityreference', $label, $test_name);
+    }
+  }
+
+  /**
+   * Test non-acceptable values for element definition.
+   */
+  public function testNonAcceptableValues() {
+    $entity_type = 'user';
+    $entity_id = 129031290;
+    $entity = new \stdClass();
+
+    $structure = array(
+      'entity_id' => $entity_id,
+      'entity_type' => 'dummy',
+    );
+
+    $wrong_structure1 = array(
+      'entity_1d' => $entity_id,
+    );
+
+    $wrong_structure2 = array(
+      // Error "Array to string conversion".
+      'entity_id' => array($entity_id),
+    );
+
+    $wrong_structure3 = array(
+      // Error "Object of class stdClass could not be converted to string".
+      'entity_id' => array($entity),
+    );
+
+    foreach (array(
+      'Try single entity ID' => $entity_id,
+      'Try list of entity IDs' => array($entity_id),
+      'Try single, correct, structure' => $structure,
+      'Try an array of correct structures' => array($structure),
+      'Try single, wrong, structure #1' => $wrong_structure1,
+      'Try an array of wrong structures #1' => array($wrong_structure1),
+      'Try single, wrong, structure #2' => $wrong_structure2,
+      'Try an array of wrong structures #2' => array($wrong_structure2),
+      'Try single, wrong, structure #3' => $wrong_structure3,
+      'Try an array of wrong structures #3' => array($wrong_structure3),
+      'Try single entity' => $entity,
+      'Try list of entities' => array($entity),
+    ) as $test_name => $default_value) {
+      $this->buildForm($entity_type, $default_value);
+      $this->assertFieldByName('entityreference', '', $test_name);
+    }
+  }
+
+}