Make it impossible to click "final check" without selecting a choice

common/lib/xmodule/xmodule/js/spec/capa/display_spec.coffee

@@ -247,6 +247,95 @@ describe 'Problem', ->
       runs ->
         expect(@problem.checkButtonLabel.text).toHaveBeenCalledWith 'Check'
 
+  describe 'check button on problems', ->
+    beforeEach ->
+      @problem = new Problem($('.xblock-student_view'))
+      @checkDisabled = (v) -> expect(@problem.checkButton.hasClass('is-disabled')).toBe(v)
+
+    describe 'some basic tests for check button', ->
+      it 'should become enabled after a value is entered into the text box', ->
+        $('#input_example_1').val('test').trigger('input')
+        @checkDisabled false
+        $('#input_example_1').val('').trigger('input')
+        @checkDisabled true
+
+    describe 'some advanced tests for check button', ->
+      it 'should become enabled after a checkbox is checked', ->
+        html = '''
+        <div class="choicegroup">
+        <label for="input_1_1_1"><input type="checkbox" name="input_1_1" id="input_1_1_1" value="1"> One</label>
+        <label for="input_1_1_2"><input type="checkbox" name="input_1_1" id="input_1_1_2" value="2"> Two</label>
+        <label for="input_1_1_3"><input type="checkbox" name="input_1_1" id="input_1_1_3" value="3"> Three</label>
+        </div>
+        '''
+        $('#input_example_1').replaceWith(html)
+        @problem.checkAnswersAndCheckButton true
+        @checkDisabled true
+        $('#input_1_1_1').attr('checked', true).trigger('click')
+        @checkDisabled false
+        $('#input_1_1_1').attr('checked', false).trigger('click')
+        @checkDisabled true
+
+      it 'should become enabled after a radiobutton is checked', ->
+        html = '''
+        <div class="choicegroup">
+        <label for="input_1_1_1"><input type="radio" name="input_1_1" id="input_1_1_1" value="1"> One</label>
+        <label for="input_1_1_2"><input type="radio" name="input_1_1" id="input_1_1_2" value="2"> Two</label>
+        <label for="input_1_1_3"><input type="radio" name="input_1_1" id="input_1_1_3" value="3"> Three</label>
+        </div>
+        '''
+        $('#input_example_1').replaceWith(html)
+        @problem.checkAnswersAndCheckButton true
+        @checkDisabled true
+        $('#input_1_1_1').attr('checked', true).trigger('click')
+        @checkDisabled false
+        $('#input_1_1_1').attr('checked', false).trigger('click')
+        @checkDisabled true
+
+      it 'should become enabled after a value is selected in a selector', ->
+        html = '''
+        <div id="problem_sel">
+        <select>
+        <option value="val0"></option>
+        <option value="val1">1</option>
+        <option value="val2">2</option>
+        </select>
+        </div>
+        '''
+        $('#input_example_1').replaceWith(html)
+        @problem.checkAnswersAndCheckButton true
+        @checkDisabled true
+        $("#problem_sel select").val("val2").trigger('change')
+        @checkDisabled false
+        $("#problem_sel select").val("val0").trigger('change')
+        @checkDisabled true
+
+      it 'should become enabled after a radiobutton is checked and a value is entered into the text box', ->
+        html = '''
+        <div class="choicegroup">
+        <label for="input_1_1_1"><input type="radio" name="input_1_1" id="input_1_1_1" value="1"> One</label>
+        <label for="input_1_1_2"><input type="radio" name="input_1_1" id="input_1_1_2" value="2"> Two</label>
+        <label for="input_1_1_3"><input type="radio" name="input_1_1" id="input_1_1_3" value="3"> Three</label>
+        </div>
+        '''
+        $(html).insertAfter('#input_example_1')
+        @problem.checkAnswersAndCheckButton true
+        @checkDisabled true
+        $('#input_1_1_1').attr('checked', true).trigger('click')
+        @checkDisabled true
+        $('#input_example_1').val('111').trigger('input')
+        @checkDisabled false
+        $('#input_1_1_1').attr('checked', false).trigger('click')
+        @checkDisabled true
+
+      it 'should become enabled if there are only hidden input fields', ->
+        html = '''
+        <input type="text" name="test" id="test" aria-describedby="answer_test" value="" style="display:none;">
+        '''
+        $('#input_example_1').replaceWith(html)
+        @problem.checkAnswersAndCheckButton true
+        @checkDisabled false
+
   describe 'reset', ->
     beforeEach ->
       @problem = new Problem($('.xblock-student_view'))

common/lib/xmodule/xmodule/js/src/capa/display.coffee

@@ -49,6 +49,8 @@ class @Problem
       window.globalTooltipManager.hide()
 
     @bindResetCorrectness()
+    if @checkButton.length
+      @checkAnswersAndCheckButton true
 
     # Collapsibles
     Collapsible.setCollapsibles(@el)
@@ -452,6 +454,58 @@ class @Problem
       element.CodeMirror.save() if element.CodeMirror.save
     @answers = @inputs.serialize()
 
+  checkAnswersAndCheckButton: (bind=false) =>
+    # Used to check available answers and if something is checked (or the answer is set in some textbox)
+    # "Check"/"Final check" button becomes enabled. Otherwise it is disabled by default.
+    # params:
+    #   'bind' used on the first check to attach event handlers to input fields
+    #     to change "Check"/"Final check" enable status in case of some manipulations with answers
+    answered = true
+
+    at_least_one_text_input_found = false
+    one_text_input_filled = false
+    @el.find("input:text").each (i, text_field) =>
+      if $(text_field).is(':visible')
+        at_least_one_text_input_found = true
+        if $(text_field).val() isnt ''
+          one_text_input_filled = true
+        if bind
+          $(text_field).on 'input', (e) =>
+            @checkAnswersAndCheckButton()
+            return
+          return
+    if at_least_one_text_input_found and not one_text_input_filled
+      answered = false
+
+    @el.find(".choicegroup").each (i, choicegroup_block) =>
+      checked = false
+      $(choicegroup_block).find("input[type=checkbox], input[type=radio]").each (j, checkbox_or_radio) =>
+        if $(checkbox_or_radio).is(':checked')
+          checked = true
+        if bind
+          $(checkbox_or_radio).on 'click', (e) =>
+            @checkAnswersAndCheckButton()
+            return
+          return
+      if not checked
+        answered = false
+        return
+
+    @el.find("select").each (i, select_field) =>
+      selected_option = $(select_field).find("option:selected").text().trim()
+      if selected_option is ''
+        answered = false
+      if bind
+        $(select_field).on 'change', (e) =>
+          @checkAnswersAndCheckButton()
+          return
+        return
+
+    if answered
+      @enableCheckButton true
+    else
+      @enableCheckButton false, false
+
   bindResetCorrectness: ->
     # Loop through all input types
     # Bind the reset functions at that scope.

common/test/acceptance/tests/lms/test_problem_types.py

@@ -6,6 +6,7 @@ See also lettuce tests in lms/djangoapps/courseware/features/problems.feature
 import random
 import textwrap
 
+from nose import SkipTest
 from abc import ABCMeta, abstractmethod
 from nose.plugins.attrib import attr
 from selenium.webdriver import ActionChains
@@ -135,6 +136,8 @@ class ProblemTypeTestMixin(object):
     """
     Test cases shared amongst problem types.
     """
+    can_submit_blank = False
+
     @attr('shard_7')
     def test_answer_correctly(self):
         """
@@ -200,15 +203,34 @@ class ProblemTypeTestMixin(object):
         Then my "<ProblemType>" answer is marked "incorrect"
         And The "<ProblemType>" problem displays a "blank" answer
         """
+        if not self.can_submit_blank:
+            raise SkipTest("Test incompatible with the current problem type")
+
         self.problem_page.wait_for(
             lambda: self.problem_page.problem_name == self.problem_name,
             "Make sure the correct problem is on the page"
         )
-
         # Leave the problem unchanged and click check.
+        self.assertNotIn('is-disabled', self.problem_page.q(css='div.problem button.check').attrs('class')[0])
         self.problem_page.click_check()
         self.wait_for_status('incorrect')
 
+    @attr('shard_7')
+    def test_cant_submit_blank_answer(self):
+        """
+        Scenario: I can't submit a blank answer
+        When I try to submit blank answer
+        Then I can't check a problem
+        """
+        if self.can_submit_blank:
+            raise SkipTest("Test incompatible with the current problem type")
+
+        self.problem_page.wait_for(
+            lambda: self.problem_page.problem_name == self.problem_name,
+            "Make sure the correct problem is on the page"
+        )
+        self.assertIn('is-disabled', self.problem_page.q(css='div.problem button.check').attrs('class')[0])
+
     @attr('a11y')
     def test_problem_type_a11y(self):
         """
@@ -236,6 +258,8 @@ class AnnotationProblemTypeTest(ProblemTypeTestBase, ProblemTypeTestMixin):
 
     factory = AnnotationResponseXMLFactory()
 
+    can_submit_blank = True
+
     factory_kwargs = {
         'title': 'Annotation Problem',
         'text': 'The text being annotated',
@@ -686,6 +710,13 @@ class CodeProblemTypeTest(ProblemTypeTestBase, ProblemTypeTestMixin):
         """
         pass
 
+    def test_cant_submit_blank_answer(self):
+        """
+        Overridden for script test because the testing grader always responds
+        with "correct"
+        """
+        pass
+
 
 class ChoiceTextProbelmTypeTestBase(ProblemTypeTestBase):
     """
@@ -801,6 +832,8 @@ class ImageProblemTypeTest(ProblemTypeTestBase, ProblemTypeTestMixin):
 
     factory = ImageResponseXMLFactory()
 
+    can_submit_blank = True
+
     factory_kwargs = {
         'src': '/static/images/placeholder-image.png',
         'rectangle': '(0,0)-(50,50)',

lms/djangoapps/courseware/features/problems.feature

@@ -180,16 +180,22 @@ Feature: LMS.Answer problems
 
         Examples:
         | ProblemType       | Points Possible    |
-        | drop down         | 1 point possible   |
-        | multiple choice   | 1 point possible   |
-        | checkbox          | 1 point possible   |
-        | radio             | 1 point possible   |
-        #| string            | 1 point possible   |
-        | numerical         | 1 point possible   |
-        | formula           | 1 point possible   |
-        | script            | 2 points possible  |
         | image             | 1 point possible   |
 
+    Scenario: I can't submit a blank answer
+        Given I am viewing a "<ProblemType>" problem
+        Then I can't check a problem
+
+        Examples:
+        | ProblemType       |
+        | drop down         |
+        | multiple choice   |
+        | checkbox          |
+        | radio             |
+        | string            |
+        | numerical         |
+        | formula           |
+        | script            |
 
     Scenario: I can reset the correctness of a problem after changing my answer
         Given I am viewing a "<ProblemType>" problem
@@ -234,21 +240,3 @@ Feature: LMS.Answer problems
         | multiple choice | incorrect          | correct          |
         | radio           | correct            | incorrect        |
         | radio           | incorrect          | correct          |
-
-
-    Scenario: I can reset the correctness of a problem after submitting a blank answer
-        Given I am viewing a "<ProblemType>" problem
-        When I check a problem
-        And I input an answer on a "<ProblemType>" problem "correctly"
-        Then my "<ProblemType>" answer is marked "unanswered"
-
-        Examples:
-        | ProblemType       |
-        | drop down         |
-        | multiple choice   |
-        | checkbox          |
-        | radio             |
-        #| string            |
-        | numerical         |
-        | formula           |
-        | script            |

lms/djangoapps/courseware/features/problems.py

@@ -92,12 +92,21 @@ def check_problem(step):
     # first scroll down so the loading mathjax button does not
     # cover up the Check button
     world.browser.execute_script("window.scrollTo(0,1024)")
+    assert world.is_css_not_present("button.check.is-disabled")
     world.css_click("button.check")
 
     # Wait for the problem to finish re-rendering
     world.wait_for_ajax_complete()
 
 
+@step(u"I can't check a problem")
+def assert_cant_check_problem(step):   # pylint: disable=unused-argument
+    # first scroll down so the loading mathjax button does not
+    # cover up the Check button
+    world.browser.execute_script("window.scrollTo(0,1024)")
+    assert world.is_css_present("button.check.is-disabled")
+
+
 @step(u'The "([^"]*)" problem displays a "([^"]*)" answer')
 def assert_problem_has_answer(step, problem_type, answer_class):
     '''