MDL-38280 manual graded behaviour: unit test for when not answered.

If the student does not submit an answer, the questoin goes to state
gaveup, rather than requiresgrading.

question/behaviour/manualgraded/tests/walkthrough_test.php

@@ -106,6 +106,48 @@ class qbehaviour_manualgraded_walkthrough_test extends qbehaviour_walkthrough_te
         $this->check_current_mark(1);
     }
 
+    public function test_manual_graded_essay_not_answered() {
+
+        // Create an essay question.
+        $essay = test_question_maker::make_an_essay_question();
+        $this->start_attempt_at_question($essay, 'deferredfeedback', 10);
+
+        // Check the right model is being used.
+        $this->assertEquals('manualgraded', $this->quba->get_question_attempt(
+                $this->slot)->get_behaviour_name());
+
+        // Check the initial state.
+        $this->check_current_state(question_state::$todo);
+        $this->check_current_mark(null);
+        $this->check_current_output($this->get_contains_question_text_expectation($essay),
+                $this->get_does_not_contain_feedback_expectation());
+
+        // Finish the attempt.
+        $this->quba->finish_all_questions();
+
+        // Verify.
+        $this->check_current_state(question_state::$gaveup);
+        $this->check_current_mark(null);
+        $this->assertEquals('',
+                $this->quba->get_response_summary($this->slot));
+
+        // Process a manual comment.
+        $this->manual_grade('Not good enough!', 1);
+
+        // Verify.
+        $this->check_current_state(question_state::$mangrpartial);
+        $this->check_current_mark(1);
+        $this->check_current_output(
+                new question_pattern_expectation('/' . preg_quote('Not good enough!') . '/'));
+
+        // Now change the max mark for the question and regrade.
+        $this->quba->regrade_question($this->slot, true, 1);
+
+        // Verify.
+        $this->check_current_state(question_state::$mangrpartial);
+        $this->check_current_mark(0.1);
+    }
+
     public function test_manual_graded_truefalse() {
 
         // Create a true-false question with correct answer true.