CONTRIB-8165 Allowing zero as an answer for text and essay.

Author: Mike Churchward

classes/responsetype/text.php

@@ -51,7 +51,7 @@ static public function response_table() {
      */
     static public function answers_from_webform($responsedata, $question) {
         $answers = [];
-        if (isset($responsedata->{'q'.$question->id}) && !empty($responsedata->{'q'.$question->id})) {
+        if (isset($responsedata->{'q'.$question->id}) && (strlen($responsedata->{'q'.$question->id}) > 0)) {
             $val = $responsedata->{'q' . $question->id};
             $record = new \stdClass();
             $record->responseid = $responsedata->rid;

tests/behat/numeric_question_zero.feature

@@ -24,10 +24,7 @@ Feature: Numeric questions can have zero as a valid response
       | Question Name | Q1 |
       | Yes | y |
       | Question Text | Enter a number |
-    Then I should see "position 1"
-    And I should see "[Numeric] (Q1)"
-    And I should see "Enter a number"
-    And I log out
+    Then I log out
 
   @javascript
   Scenario: Student must enter no more than six digits and decimal points.

tests/behat/text_question_zero.feature

@@ -0,0 +1,43 @@
+@mod @mod_questionnaire
+Feature: Text questions can have zero as a valid response
+
+  Background: Add a text question to a questionnaire and accept zero
+    Given the following "users" exist:
+      | username | firstname | lastname | email |
+      | teacher1 | Teacher | 1 | teacher1@example.com |
+      | student1 | Student | 1 | student1@example.com |
+    And the following "courses" exist:
+      | fullname | shortname | category |
+      | Course 1 | C1 | 0 |
+    And the following "course enrolments" exist:
+      | user | course | role |
+      | teacher1 | C1 | editingteacher |
+      | student1 | C1 | student |
+    And the following "activities" exist:
+      | activity | name | description | course | idnumber |
+      | questionnaire | Test questionnaire | Test questionnaire description | C1 | questionnaire0 |
+    And I log in as "teacher1"
+    And I am on "Course 1" course homepage
+    And I follow "Test questionnaire"
+    And I navigate to "Questions" in current page administration
+    And I add a "Text Box" question and I fill the form with:
+      | Question Name | Q1 |
+      | Yes | y |
+      | Question Text | Enter zero |
+    Then I log out
+
+  @javascript
+  Scenario: Student must enter no more than six digits and decimal points.
+    And I log in as "student1"
+    And I am on "Course 1" course homepage
+    And I follow "Test questionnaire"
+    And I navigate to "Answer the questions..." in current page administration
+    Then I should see "Enter zero"
+    And I set the field "Enter zero" to "0"
+    And I press "Submit questionnaire"
+    Then I should see "Thank you for completing this Questionnaire."
+    And I press "Continue"
+    Then I should see "Your response"
+    And I should see "Test questionnaire"
+    And I should see "Enter zero"
+    And "//div[contains(@class,'questionnaire_text') and contains(@class,'questionnaire_response')]//span[@class='selected' and text()='0']" "xpath_element" should exist