diff --git a/admin/tool/behat/tests/behat/data_generators.feature b/admin/tool/behat/tests/behat/data_generators.feature
index 1081477abe0..19c8c73b744 100644
--- a/admin/tool/behat/tests/behat/data_generators.feature
+++ b/admin/tool/behat/tests/behat/data_generators.feature
@@ -271,3 +271,20 @@ Feature: Set up contextual data for tests
       | Name               | Cohort size |
       | Cohort in category | 1           |
       | Empty cohort       | 0           |
+
+  Scenario: Add grade categories with data generator
+    Given the following "courses" exist:
+      | fullname | shortname |
+      | Course 1 | C1 |
+    And the following "grade categories" exist:
+      | fullname | course |
+      | Grade category 1 | C1|
+    And the following "grade categories" exist:
+      | fullname | course | gradecategory |
+      | Grade sub category 2 | C1 | Grade category 1|
+    When I log in as "admin"
+    And I follow "Courses"
+    And I follow "Course 1"
+    And I navigate to "Grades" node in "Course administration"
+    Then I should see "Grade category 1"
+    And I should see "Grade sub category 2"
diff --git a/grade/tests/behat/grade_aggregation.feature b/grade/tests/behat/grade_aggregation.feature
index 3c159b36bb2..1ca89eeb428 100644
--- a/grade/tests/behat/grade_aggregation.feature
+++ b/grade/tests/behat/grade_aggregation.feature
@@ -16,11 +16,26 @@ Feature: We can use calculated grade totals
       | user | course | role |
       | teacher1 | C1 | editingteacher |
       | student1 | C1 | student |
+    And the following "grade categories" exist:
+      | fullname | course |
+      | Sub category 1 | C1|
+      | Sub category 2 | C1|
     And the following "activities" exist:
-      | activity | course | idnumber | name | intro |
-      | assign | C1 | a1 | Test assignment one | Submit something! |
-      | assign | C1 | a2 | Test assignment two | Submit something! |
-      | assign | C1 | a3 | Test assignment three | Submit something! |
+      | activity | course | idnumber | name | intro | grade |
+      | assign | C1 | a1 | Test assignment one | Submit something! | 300 |
+      | assign | C1 | a2 | Test assignment two | Submit something! | 100 |
+      | assign | C1 | a3 | Test assignment three | Submit something! | 150 |
+      | assign | C1 | a4 | Test assignment four | Submit nothing! | 150 |
+    And the following "activities" exist:
+      | activity | course | idnumber | name | intro | gradecategory | grade |
+      | assign | C1 | a5 | Test assignment five | Submit something! | Sub category 1 | 200
+      | assign | C1 | a6 | Test assignment six | Submit something! | Sub category 1 | 100
+      | assign | C1 | a7 | Test assignment seven | Submit nothing! | Sub category 1 | 150
+    And the following "activities" exist:
+      | activity | course | idnumber | name | intro | gradecategory | grade |
+      | assign | C1 | a8 | Test assignment eight | Submit something! | Sub category 2 | 200
+      | assign | C1 | a9 | Test assignment nine | Submit something! | Sub category 2 | 100
+      | assign | C1 | 10 | Test assignment ten | Submit nothing! | Sub category 2 | 150
     And I log in as "teacher1"
     And I follow "Course 1"
     And I follow "Grades"
@@ -28,10 +43,20 @@ Feature: We can use calculated grade totals
     And I give the grade "60.00" to the user "Student 1" for the grade item "Test assignment one"
     And I give the grade "20.00" to the user "Student 1" for the grade item "Test assignment two"
     And I give the grade "40.00" to the user "Student 1" for the grade item "Test assignment three"
+    And I give the grade "10.00" to the user "Student 1" for the grade item "Test assignment five"
+    And I give the grade "5.00" to the user "Student 1" for the grade item "Test assignment six"
+    And I give the grade "10.00" to the user "Student 1" for the grade item "Test assignment eight"
+    And I give the grade "5.00" to the user "Student 1" for the grade item "Test assignment nine"
     And I press "Update"
     And I click on "Edit  assign Test assignment two" "link"
     And I click on "Hidden" "checkbox"
     And I press "Save changes"
+    And I click on "Edit  assign Test assignment five" "link"
+    And I click on "Hidden" "checkbox"
+    And I press "Save changes"
+    And I click on "Edit  assign Test assignment eight" "link"
+    And I click on "Hidden" "checkbox"
+    And I press "Save changes"
     And I follow "Course grade settings"
     And I set the field "Grade display type" to "Real (percentage)"
     And I press "Save changes"
@@ -41,8 +66,16 @@ Feature: We can use calculated grade totals
     And I follow "Edit   Course 1"
     And I set the field "Aggregation" to "Mean of grades"
     And I press "Save changes"
+    And I follow "Edit   Sub category 1"
+    And I set the field "Aggregation" to "Mean of grades"
+    And I press "Save changes"
+    And I follow "Edit   Sub category 2"
+    And I set the field "Aggregation" to "Mean of grades"
+    And I click on "Show more..." "link"
+    And I click on "Aggregate only non-empty grades" "checkbox"
+    And I press "Save changes"
     And I turn editing mode off
-    Then I should see "40.00 (40.00 %)" in the ".course" "css_element"
+    Then I should see "30.00 (30.00 %)" in the ".course" "css_element"
     And I follow "Course grade settings"
     And I set the field "Hide totals if they contain hidden items" to "Show totals excluding hidden items"
     And I press "Save changes"
@@ -51,18 +84,30 @@ Feature: We can use calculated grade totals
     And I follow "Course 1"
     And I follow "Grades"
     And I set the field "Grade report" to "Overview report"
-    And I should see "50.00 (50.00 %)" in the "overview-grade" "table"
+    And I should see "30.42 (30.42 %)" in the "overview-grade" "table"
 
   @javascript
   Scenario: Weighted mean of grades aggregation
     And I follow "Edit   Course 1"
     And I set the field "Aggregation" to "Weighted mean of grades"
     And I press "Save changes"
+    And I follow "Edit   Sub category 1"
+    And I set the field "Aggregation" to "Weighted mean of grades"
+    And I expand all fieldsets
+    And I set the field "Item weight" to "1"
+    And I press "Save changes"
+    And I follow "Edit   Sub category 2"
+    And I set the field "Aggregation" to "Weighted mean of grades"
+    And I expand all fieldsets
+    And I set the field "Item weight" to "1"
+    And I click on "Aggregate only non-empty grades" "checkbox"
+    And I press "Save changes"
     And I click on "Edit  assign Test assignment one" "link"
+    And I expand all fieldsets
     And I set the field "Item weight" to "3"
     And I press "Save changes"
     And I turn editing mode off
-    Then I should see "48.00 (48.00 %)" in the ".course" "css_element"
+    Then I should see "27.14 (27.14 %)" in the ".course" "css_element"
     And I follow "Course grade settings"
     And I set the field "Hide totals if they contain hidden items" to "Show totals excluding hidden items"
     And I press "Save changes"
@@ -71,15 +116,27 @@ Feature: We can use calculated grade totals
     And I follow "Course 1"
     And I follow "Grades"
     And I set the field "Grade report" to "Overview report"
-    And I should see "55.00 (55.00 %)" in the "overview-grade" "table"
+    And I should see "26.94 (26.94 %)" in the "overview-grade" "table"
 
   @javascript
   Scenario: Simple weighted mean of grades aggregation
     And I follow "Edit   Course 1"
     And I set the field "Aggregation" to "Simple weighted mean of grades"
     And I press "Save changes"
+    And I follow "Edit   Sub category 1"
+    And I set the field "Aggregation" to "Simple weighted mean of grades"
+    And I press "Save changes"
+    And I follow "Edit   Sub category 2"
+    And I set the field "Aggregation" to "Simple weighted mean of grades"
+    And I click on "Show more..." "link"
+    And I click on "Aggregate only non-empty grades" "checkbox"
+    And I press "Save changes"
+    And I click on "Edit  assign Test assignment one" "link"
+    And I expand all fieldsets
+    And I click on "Extra credit" "checkbox"
+    And I press "Save changes"
     And I turn editing mode off
-    Then I should see "40.00 (40.00 %)" in the ".course" "css_element"
+    Then I should see "45.19 (45.19 %)" in the ".course" "css_element"
     And I follow "Course grade settings"
     And I set the field "Hide totals if they contain hidden items" to "Show totals excluding hidden items"
     And I press "Save changes"
@@ -88,15 +145,27 @@ Feature: We can use calculated grade totals
     And I follow "Course 1"
     And I follow "Grades"
     And I set the field "Grade report" to "Overview report"
-    And I should see "50.00 (50.00 %)" in the "overview-grade" "table"
+    And I should see "48.57 (48.57 %)" in the "overview-grade" "table"
 
   @javascript
   Scenario: Mean of grades (with extra credits) aggregation
     And I follow "Edit   Course 1"
     And I set the field "Aggregation" to "Mean of grades (with extra credits)"
     And I press "Save changes"
+    And I follow "Edit   Sub category 1"
+    And I set the field "Aggregation" to "Mean of grades (with extra credits)"
+    And I press "Save changes"
+    And I follow "Edit   Sub category 2"
+    And I set the field "Aggregation" to "Mean of grades (with extra credits)"
+    And I click on "Show more..." "link"
+    And I click on "Aggregate only non-empty grades" "checkbox"
+    And I press "Save changes"
+    And I click on "Edit  assign Test assignment one" "link"
+    And I expand all fieldsets
+    And I set the field "Extra credit weight" to "2"
+    And I press "Save changes"
     And I turn editing mode off
-    Then I should see "40.00 (40.00 %)" in the ".course" "css_element"
+    Then I should see "42.50 (42.50 %)" in the ".course" "css_element"
     And I follow "Course grade settings"
     And I set the field "Hide totals if they contain hidden items" to "Show totals excluding hidden items"
     And I press "Save changes"
@@ -105,15 +174,82 @@ Feature: We can use calculated grade totals
     And I follow "Course 1"
     And I follow "Grades"
     And I set the field "Grade report" to "Overview report"
-    And I should see "50.00 (50.00 %)" in the "overview-grade" "table"
+    And I should see "47.22 (47.22 %)" in the "overview-grade" "table"
 
   @javascript
   Scenario: Median of grades aggregation
     And I follow "Edit   Course 1"
     And I set the field "Aggregation" to "Median of grades"
     And I press "Save changes"
+    And I follow "Edit   Sub category 1"
+    And I set the field "Aggregation" to "Median of grades"
+    And I press "Save changes"
+    And I follow "Edit   Sub category 2"
+    And I set the field "Aggregation" to "Median of grades"
+    And I click on "Show more..." "link"
+    And I click on "Aggregate only non-empty grades" "checkbox"
+    And I press "Save changes"
     And I turn editing mode off
-    Then I should see "40.00 (40.00 %)" in the ".course" "css_element"
+    Then I should see "26.67 (26.67 %)" in the ".course" "css_element"
+    And I follow "Course grade settings"
+    And I set the field "Hide totals if they contain hidden items" to "Show totals excluding hidden items"
+    And I press "Save changes"
+    And I log out
+    And I log in as "student1"
+    And I follow "Course 1"
+    And I follow "Grades"
+    And I set the field "Grade report" to "Overview report"
+    And I should see "25.83 (25.83 %)" in the "overview-grade" "table"
+
+  @javascript
+  Scenario: Lowest grade aggregation
+    And I follow "Edit   Course 1"
+    And I set the field "Aggregation" to "Lowest grade"
+    And I press "Save changes"
+    And I follow "Edit   Sub category 1"
+    And I set the field "Aggregation" to "Lowest grade"
+    And I press "Save changes"
+    And I follow "Edit   Sub category 2"
+    And I set the field "Aggregation" to "Lowest grade"
+    And I click on "Show more..." "link"
+    And I click on "Aggregate only non-empty grades" "checkbox"
+    And I press "Save changes"
+    And I click on "Edit  assign Test assignment five" "link"
+    And I click on "Hidden" "checkbox"
+    And I press "Save changes"
+    And I click on "Edit  assign Test assignment four" "link"
+    And I click on "Hidden" "checkbox"
+    And I press "Save changes"
+    And I turn editing mode off
+    Then I should see "0.00 (0.00 %)" in the ".course" "css_element"
+    And I follow "Course grade settings"
+    And I set the field "Hide totals if they contain hidden items" to "Show totals excluding hidden items"
+    And I press "Save changes"
+    And I log out
+    And I log in as "student1"
+    And I follow "Course 1"
+    And I follow "Grades"
+    And I set the field "Grade report" to "Overview report"
+    And I should see "0.00 (0.00 %)" in the "overview-grade" "table"
+
+  @javascript
+  Scenario: Highest grade aggregation
+    And I follow "Edit   Course 1"
+    And I set the field "Aggregation" to "Highest grade"
+    And I press "Save changes"
+    And I follow "Edit   Sub category 1"
+    And I set the field "Aggregation" to "Highest grade"
+    And I press "Save changes"
+    And I follow "Edit   Sub category 2"
+    And I set the field "Aggregation" to "Highest grade"
+    And I click on "Show more..." "link"
+    And I click on "Aggregate only non-empty grades" "checkbox"
+    And I press "Save changes"
+    And I click on "Edit  assign Test assignment one" "link"
+    And I click on "Hidden" "checkbox"
+    And I press "Save changes"
+    And I turn editing mode off
+    Then I should see "50.00 (50.00 %)" in the ".course" "css_element"
     And I follow "Course grade settings"
     And I set the field "Hide totals if they contain hidden items" to "Show totals excluding hidden items"
     And I press "Save changes"
@@ -124,53 +260,24 @@ Feature: We can use calculated grade totals
     And I set the field "Grade report" to "Overview report"
     And I should see "50.00 (50.00 %)" in the "overview-grade" "table"
 
-  @javascript
-  Scenario: Lowest grade aggregation
-    And I follow "Edit   Course 1"
-    And I set the field "Aggregation" to "Lowest grade"
-    And I press "Save changes"
-    And I turn editing mode off
-    Then I should see "20.00 (20.00 %)" in the ".course" "css_element"
-    And I follow "Course grade settings"
-    And I set the field "Hide totals if they contain hidden items" to "Show totals excluding hidden items"
-    And I press "Save changes"
-    And I log out
-    And I log in as "student1"
-    And I follow "Course 1"
-    And I follow "Grades"
-    And I set the field "Grade report" to "Overview report"
-    And I should see "40.00 (40.00 %)" in the "overview-grade" "table"
-
-  @javascript
-  Scenario: Highest grade aggregation
-    And I follow "Edit   Course 1"
-    And I set the field "Aggregation" to "Highest grade"
-    And I press "Save changes"
-    And I click on "Edit  assign Test assignment one" "link"
-    And I click on "Hidden" "checkbox"
-    And I press "Save changes"
-    And I turn editing mode off
-    Then I should see "60.00 (60.00 %)" in the ".course" "css_element"
-    And I follow "Course grade settings"
-    And I set the field "Hide totals if they contain hidden items" to "Show totals excluding hidden items"
-    And I press "Save changes"
-    And I log out
-    And I log in as "student1"
-    And I follow "Course 1"
-    And I follow "Grades"
-    And I set the field "Grade report" to "Overview report"
-    And I should see "40.00 (40.00 %)" in the "overview-grade" "table"
-
   @javascript
   Scenario: Mode of grades aggregation
     And I follow "Edit   Course 1"
     And I set the field "Aggregation" to "Mode of grades"
     And I press "Save changes"
+    And I follow "Edit   Sub category 1"
+    And I set the field "Aggregation" to "Mode of grades"
+    And I press "Save changes"
+    And I follow "Edit   Sub category 2"
+    And I set the field "Aggregation" to "Mode of grades"
+    And I click on "Show more..." "link"
+    And I click on "Aggregate only non-empty grades" "checkbox"
+    And I press "Save changes"
     And I click on "Edit  assign Test assignment one" "link"
     And I click on "Hidden" "checkbox"
     And I press "Save changes"
     And I turn editing mode off
-    Then I should see "60.00 (60.00 %)" in the ".course" "css_element"
+    Then I should see "50.00 (50.00 %)" in the ".course" "css_element"
     And I follow "Course grade settings"
     And I set the field "Hide totals if they contain hidden items" to "Show totals excluding hidden items"
     And I press "Save changes"
@@ -179,15 +286,21 @@ Feature: We can use calculated grade totals
     And I follow "Course 1"
     And I follow "Grades"
     And I set the field "Grade report" to "Overview report"
-    And I should see "40.00 (40.00 %)" in the "overview-grade" "table"
+    And I should see "50.00 (50.00 %)" in the "overview-grade" "table"
 
   @javascript
   Scenario: Sum of grades aggregation
+    And I follow "Edit   Sub category 1"
+    And I set the field "Aggregation" to "Sum of grades"
+    And I press "Save changes"
+    And I follow "Edit   Sub category 2"
+    And I set the field "Aggregation" to "Sum of grades"
+    And I press "Save changes"
     And I follow "Edit   Course 1"
     And I set the field "Aggregation" to "Sum of grades"
     And I press "Save changes"
     And I turn editing mode off
-    Then I should see "120.00 (40.00 %)" in the ".course" "css_element"
+    Then I should see "150.00 (18.99 %)" in the ".course" "css_element"
     And I follow "Course grade settings"
     And I set the field "Hide totals if they contain hidden items" to "Show totals excluding hidden items"
     And I press "Save changes"
@@ -196,4 +309,4 @@ Feature: We can use calculated grade totals
     And I follow "Course 1"
     And I follow "Grades"
     And I set the field "Grade report" to "Overview report"
-    And I should see "100.00 (50.00 %)" in the "overview-grade" "table"
+    And I should see "110.00 (16.92 %)" in the "overview-grade" "table"
diff --git a/lib/testing/generator/data_generator.php b/lib/testing/generator/data_generator.php
index 1171bda5740..32713b012c2 100644
--- a/lib/testing/generator/data_generator.php
+++ b/lib/testing/generator/data_generator.php
@@ -34,6 +34,7 @@ defined('MOODLE_INTERNAL') || die();
  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  */
 class testing_data_generator {
+    protected $gradecategorycounter = 0;
     protected $usercounter = 0;
     protected $categorycount = 0;
     protected $cohortcount = 0;
@@ -740,6 +741,39 @@ EOD;
         return role_assign($roleid, $userid, $contextid);
     }
 
+    /**
+     * Create a grade_category.
+     *
+     * @param array|stdClass $record
+     * @return stdClass the grade category record
+     */
+    public function create_grade_category($record = null) {
+        global $CFG;
+
+        $this->gradecategorycounter++;
+        $i = $this->gradecategorycounter;
+
+        if (!isset($record['fullname'])) {
+            $record['fullname'] = 'Grade category ' . $i;
+        }
+
+        // For gradelib classes.
+        require_once($CFG->libdir . '/gradelib.php');
+        // Create new grading category in this course.
+        $gradecategory = new grade_category($record, false);
+        $gradecategory->apply_default_settings();
+        $gradecategory->apply_forced_settings();
+        $gradecategory->insert();
+        // This creates a default grade item for the category
+        $gradeitem = $gradecategory->load_grade_item();
+
+        if (isset($record->parentcategory)) {
+            $gradecategory->set_parent($data->parentcategory);
+        }
+
+        $gradecategory->update_from_db();
+        return $gradecategory->get_record_data();
+    }
 }
 
 /**
diff --git a/lib/testing/tests/generator_test.php b/lib/testing/tests/generator_test.php
index 110f28fc225..a55a5a85e73 100644
--- a/lib/testing/tests/generator_test.php
+++ b/lib/testing/tests/generator_test.php
@@ -105,6 +105,15 @@ class core_test_generator_testcase extends advanced_testcase {
 
         $scale = $generator->create_scale();
         $this->assertNotEmpty($scale);
+
+        // Note we only count grade cats with depth > 1 because the course grade category
+        // is lazily created.
+        $count = $DB->count_records_select('grade_categories', 'depth <> 1');
+        $gradecategory = $generator->create_grade_category(array('courseid'=>$course->id));
+        $this->assertEquals($count+1, $DB->count_records_select('grade_categories', 'depth <> 1'));
+        $this->assertEquals(2, $gradecategory->depth);
+        $this->assertEquals($course->id, $gradecategory->courseid);
+        $this->assertEquals('Grade category 1', $gradecategory->fullname);
     }
 
     public function test_create_module() {
diff --git a/lib/tests/behat/behat_data_generators.php b/lib/tests/behat/behat_data_generators.php
index 285bf5ed054..0820ed26347 100644
--- a/lib/tests/behat/behat_data_generators.php
+++ b/lib/tests/behat/behat_data_generators.php
@@ -115,7 +115,7 @@ class behat_data_generators extends behat_base {
         'activities' => array(
             'datagenerator' => 'activity',
             'required' => array('activity', 'idnumber', 'course'),
-            'switchids' => array('course' => 'course')
+            'switchids' => array('course' => 'course', 'gradecategory' => 'gradecat')
         ),
         'group members' => array(
             'datagenerator' => 'group_member',
@@ -135,6 +135,11 @@ class behat_data_generators extends behat_base {
             'datagenerator' => 'cohort_member',
             'required' => array('user', 'cohort'),
             'switchids' => array('user' => 'userid', 'cohort' => 'cohortid')
+        ),
+        'grade categories' => array(
+            'datagenerator' => 'grade_category',
+            'required' => array('fullname', 'course'),
+            'switchids' => array('course' => 'courseid', 'gradecategory' => 'parent')
         )
     );
 
@@ -428,6 +433,21 @@ class behat_data_generators extends behat_base {
         cohort_add_member($data['cohortid'], $data['userid']);
     }
 
+    /**
+     * Gets the grade category id from the grade category fullname
+     * @throws Exception
+     * @param string $username
+     * @return int
+     */
+    protected function get_gradecategory_id($fullname) {
+        global $DB;
+
+        if (!$id = $DB->get_field('grade_categories', 'id', array('fullname' => $fullname))) {
+            throw new Exception('The specified grade category with fullname "' . $fullname . '" does not exist');
+        }
+        return $id;
+    }
+
     /**
      * Gets the user id from it's username.
      * @throws Exception