diff --git a/comment/tests/context_freeze_test.php b/comment/tests/context_freeze_test.php
new file mode 100644
index 00000000000..36f1d600bca
--- /dev/null
+++ b/comment/tests/context_freeze_test.php
@@ -0,0 +1,166 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Tests for comments when the context is frozen.
+ *
+ * @package    core_comment
+ * @copyright  2019 University of Nottingham
+ * @author     Neill Magill <neill.magill@nottingham.ac.uk>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+defined('MOODLE_INTERNAL') || die();
+
+/**
+ * Tests for comments when the context is frozen.
+ *
+ * @package    core_comment
+ * @copyright  2019 University of Nottingham
+ * @author     Neill Magill <neill.magill@nottingham.ac.uk>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class comment_context_freeze_testcase extends advanced_testcase {
+    /**
+     * Creates a comment by a student.
+     *
+     * Returns:
+     * - The comment object
+     * - The sudent that wrote the comment
+     * - The arguments used to create the comment
+     *
+     * @param stdClass $course Moodle course from the datagenerator
+     * @return array
+     */
+    protected function create_student_comment_and_freeze_course($course): array {
+        set_config('contextlocking', 1);
+
+        $context = context_course::instance($course->id);
+        $student = $this->getDataGenerator()->create_and_enrol($course, 'student');
+
+        $args = new stdClass;
+        $args->context = $context;
+        $args->course = $course;
+        $args->area = 'page_comments';
+        $args->itemid = 0;
+        $args->component = 'block_comments';
+        $args->linktext = get_string('showcomments');
+        $args->notoggle = true;
+        $args->autostart = true;
+        $args->displaycancel = false;
+
+        // Create a comment by the student.
+        $this->setUser($student);
+        $comment = new comment($args);
+        $newcomment = $comment->add('New comment');
+
+        // Freeze the context.
+        $this->setAdminUser();
+        $context->set_locked(true);
+
+        return [$newcomment, $student, $args];
+    }
+
+    /**
+     * Test that a student cannot delete their own comments in frozen contexts via the external service.
+     */
+    public function test_delete_student_external() {
+        global $CFG;
+        require_once($CFG->dirroot . '/comment/lib.php');
+
+        $this->resetAfterTest();
+
+        $course = $this->getDataGenerator()->create_course();
+
+        list($newcomment, $student, $args) = $this->create_student_comment_and_freeze_course($course);
+
+        // Check that a student cannot delete their own comment.
+        $this->setUser($student);
+        $studentcomment = new comment($args);
+        $this->assertFalse($studentcomment->can_delete($newcomment->id));
+        $this->assertFalse($studentcomment->can_post());
+        $this->expectException(comment_exception::class);
+        $this->expectExceptionMessage(get_string('nopermissiontodelentry', 'error'));
+        core_comment_external::delete_comments([$newcomment->id]);
+    }
+
+    /**
+     * Test that a student cannot delete their own comments in frozen contexts.
+     */
+    public function test_delete_student() {
+        global $CFG;
+        require_once($CFG->dirroot . '/comment/lib.php');
+
+        $this->resetAfterTest();
+
+        $course = $this->getDataGenerator()->create_course();
+
+        list($newcomment, $student, $args) = $this->create_student_comment_and_freeze_course($course);
+
+        // Check that a student cannot delete their own comment.
+        $this->setUser($student);
+        $studentcomment = new comment($args);
+        $this->assertFalse($studentcomment->can_delete($newcomment->id));
+        $this->assertFalse($studentcomment->can_post());
+        $this->expectException(comment_exception::class);
+        $this->expectExceptionMessage(get_string('nopermissiontocomment', 'error'));
+        $studentcomment->delete($newcomment->id);
+    }
+
+    /**
+     * Test that an admin cannot delete comments in frozen contexts via the external service.
+     */
+    public function test_delete_admin_external() {
+        global $CFG;
+        require_once($CFG->dirroot . '/comment/lib.php');
+
+        $this->resetAfterTest();
+
+        $course = $this->getDataGenerator()->create_course();
+
+        list($newcomment, $student, $args) = $this->create_student_comment_and_freeze_course($course);
+
+        // Check that the admin user cannot delete the comment.
+        $admincomment = new comment($args);
+        $this->assertFalse($admincomment->can_delete($newcomment->id));
+        $this->assertFalse($admincomment->can_post());
+        $this->expectException(comment_exception::class);
+        $this->expectExceptionMessage(get_string('nopermissiontodelentry', 'error'));
+        core_comment_external::delete_comments([$newcomment->id]);
+    }
+
+    /**
+     * Test that an admin cannot delete comments in frozen contexts.
+     */
+    public function test_delete_admin() {
+        global $CFG;
+        require_once($CFG->dirroot . '/comment/lib.php');
+
+        $this->resetAfterTest();
+
+        $course = $this->getDataGenerator()->create_course();
+
+        list($newcomment, $student, $args) = $this->create_student_comment_and_freeze_course($course);
+
+        // Check that the admin user cannot delete the comment.
+        $admincomment = new comment($args);
+        $this->assertFalse($admincomment->can_delete($newcomment->id));
+        $this->assertFalse($admincomment->can_post());
+        $this->expectException(comment_exception::class);
+        $this->expectExceptionMessage(get_string('nopermissiontocomment', 'error'));
+        $admincomment->delete($newcomment->id);
+    }
+}