MDL-79971 completion: Don't assume a completed activity is viewed

lib/completionlib.php

@@ -1650,11 +1650,12 @@ class completion_info {
                 $data->coursemoduleid = $data->cmvcoursemoduleid;
                 $data->userid = $data->cmvuserid;
             }
+            // When reseting all state in the completion, we need to keep current view state.
+            // We cannot assume the activity has been viewed, so we should check if there is any course_modules_viewed already.
+            $data->viewed = is_null($data->cmvuserid) ? 0 : 1;
+
             unset($data->cmvcoursemoduleid);
             unset($data->cmvuserid);
-
-            // When reseting all state in the completion, we need to keep current view state.
-            $data->viewed = 1;
         }
 
         return (array)$data;

lib/tests/completionlib_test.php

@@ -876,6 +876,7 @@ class completionlib_test extends advanced_testcase {
      * @covers ::get_completion_data
      */
     public function test_get_completion_data() {
+        $this->setAdminUser();
         $this->setup_data();
         $choicegenerator = $this->getDataGenerator()->get_plugin_generator('mod_choice');
         $choice = $choicegenerator->create_instance([
@@ -905,6 +906,11 @@ class completionlib_test extends advanced_testcase {
         $this->assertEquals(0, $completiondatabeforeview['viewed']);
         $this->assertEquals($cm->id, $completiondatabeforeview['coursemoduleid']);
 
+        // Mark as completed before viewing it.
+        $completioninfo->update_state($cm, COMPLETION_COMPLETE, $this->user->id, true);
+        $completiondatabeforeview = $completioninfo->get_completion_data($cm->id, $this->user->id, $defaultdata);
+        $this->assertEquals(0, $completiondatabeforeview['viewed']);
+
         // Set viewed.
         $completioninfo->set_module_viewed($cm, $this->user->id);