Fix max_attempts=''

That's what studio defaults to, and recent changes made it break.
Added a few tests to make sure it doesn't happen again.

common/lib/capa/capa/tests/test_html_render.py

@@ -11,6 +11,20 @@ from . import test_system
 
 class CapaHtmlRenderTest(unittest.TestCase):
 
+    def test_blank_problem(self):
+        """
+        It's important that blank problems don't break, since that's
+        what you start with in studio.
+        """
+        xml_str = "<problem> </problem>"
+
+        # Create the problem
+        problem = LoncapaProblem(xml_str, '1', system=test_system)
+
+        # Render the HTML
+        rendered_html = etree.XML(problem.get_html())
+        # expect that we made it here without blowing up
+
     def test_include_html(self):
         # Create a test file to include
         self._create_test_file('test_include.xml',
@@ -25,7 +39,7 @@ class CapaHtmlRenderTest(unittest.TestCase):
 
         # Create the problem
         problem = LoncapaProblem(xml_str, '1', system=test_system)
-    
+
         # Render the HTML
         rendered_html = etree.XML(problem.get_html())
 
@@ -45,7 +59,7 @@ class CapaHtmlRenderTest(unittest.TestCase):
 
         # Create the problem
         problem = LoncapaProblem(xml_str, '1', system=test_system)
-    
+
         # Render the HTML
         rendered_html = etree.XML(problem.get_html())
 
@@ -64,7 +78,7 @@ class CapaHtmlRenderTest(unittest.TestCase):
 
         # Create the problem
         problem = LoncapaProblem(xml_str, '1', system=test_system)
-    
+
         # Render the HTML
         rendered_html = etree.XML(problem.get_html())
 
@@ -99,11 +113,11 @@ class CapaHtmlRenderTest(unittest.TestCase):
         response_element = rendered_html.find("span")
         self.assertEqual(response_element.tag, "span")
 
-        # Expect that the response <span> 
+        # Expect that the response <span>
         # that contains a <div> for the textline
         textline_element = response_element.find("div")
         self.assertEqual(textline_element.text, 'Input Template Render')
-        
+
         # Expect a child <div> for the solution
         # with the rendered template
         solution_element = rendered_html.find("div")
@@ -112,14 +126,14 @@ class CapaHtmlRenderTest(unittest.TestCase):
         # Expect that the template renderer was called with the correct
         # arguments, once for the textline input and once for
         # the solution
-        expected_textline_context = {'status': 'unsubmitted', 
-                                        'value': '', 
-                                        'preprocessor': None, 
-                                        'msg': '', 
-                                        'inline': False, 
-                                        'hidden': False, 
-                                        'do_math': False, 
-                                        'id': '1_2_1', 
+        expected_textline_context = {'status': 'unsubmitted',
+                                        'value': '',
+                                        'preprocessor': None,
+                                        'msg': '',
+                                        'inline': False,
+                                        'hidden': False,
+                                        'do_math': False,
+                                        'id': '1_2_1',
                                         'size': None}
 
         expected_solution_context = {'id': '1_solution_1'}
@@ -148,7 +162,7 @@ class CapaHtmlRenderTest(unittest.TestCase):
 
         # Create the problem and render the html
         problem = LoncapaProblem(xml_str, '1', system=test_system)
-        
+
         # Grade the problem
         correctmap = problem.grade_answers({'1_2_1': 'test'})
 

common/lib/xmodule/xmodule/capa_module.py

@@ -135,8 +135,8 @@ class CapaModule(XModule):
             self.grace_period = None
             self.close_date = self.display_due_date
 
-        max_attempts = self.metadata.get('attempts', None)
-        if max_attempts is not None:
+        max_attempts = self.metadata.get('attempts')
+        if max_attempts is not None and max_attempts != '':
             self.max_attempts = int(max_attempts)
         else:
             self.max_attempts = None

common/lib/xmodule/xmodule/tests/test_capa_module.py

@@ -44,7 +44,7 @@ class CapaFactory(object):
     @staticmethod
     def answer_key():
         """ Return the key stored in the capa problem answer dict """
-        return ("-".join(['i4x', 'edX', 'capa_test', 'problem', 
+        return ("-".join(['i4x', 'edX', 'capa_test', 'problem',
                         'SampleProblem%d' % CapaFactory.num]) +
                 "_2_1")
 
@@ -144,6 +144,8 @@ class CapaModuleTest(unittest.TestCase):
                             "Factory should be creating unique names for each problem")
 
 
+
+
     def test_correct(self):
         """
         Check that the factory creates correct and incorrect problems properly.
@@ -332,7 +334,7 @@ class CapaModuleTest(unittest.TestCase):
                         'input_4': None,
                         'input_5': [],
                         'input_6': 5}
-        
+
         result = CapaModule.make_dict_of_responses(valid_get_dict)
 
         # Expect that we get a dict with "input" stripped from key names
@@ -475,7 +477,7 @@ class CapaModuleTest(unittest.TestCase):
 
             mock_is_queued.return_value = True
             mock_get_queuetime.return_value = datetime.datetime.now()
-        
+
             get_request_dict = { CapaFactory.input_key(): '3.14' }
             result = module.check_problem(get_request_dict)
 
@@ -506,7 +508,7 @@ class CapaModuleTest(unittest.TestCase):
     def test_reset_problem(self):
         module = CapaFactory.create()
 
-        # Mock the module's capa problem 
+        # Mock the module's capa problem
         # to simulate that the problem is done
         mock_problem = MagicMock(capa.capa_problem.LoncapaProblem)
         mock_problem.done = True
@@ -668,7 +670,7 @@ class CapaModuleTest(unittest.TestCase):
         module = CapaFactory.create(max_attempts=0)
         self.assertFalse(module.should_show_check_button())
 
-        # If user submitted a problem but hasn't reset, 
+        # If user submitted a problem but hasn't reset,
         # do NOT show the check button
         # Note:  we can only reset when rerandomize="always"
         module = CapaFactory.create(rerandomize="always")
@@ -707,7 +709,7 @@ class CapaModuleTest(unittest.TestCase):
         module.lcp.done = True
         self.assertFalse(module.should_show_reset_button())
 
-        # If the user hasn't submitted an answer yet, 
+        # If the user hasn't submitted an answer yet,
         # then do NOT show the reset button
         module = CapaFactory.create()
         module.lcp.done = False
@@ -770,7 +772,7 @@ class CapaModuleTest(unittest.TestCase):
 
         # If the user is out of attempts, do NOT show the save button
         attempts = random.randint(1,10)
-        module = CapaFactory.create(attempts=attempts, 
+        module = CapaFactory.create(attempts=attempts,
                                     max_attempts=attempts,
                                     force_save_button="true")
         module.lcp.done = True
@@ -784,6 +786,12 @@ class CapaModuleTest(unittest.TestCase):
         module.lcp.done = True
         self.assertTrue(module.should_show_save_button())
 
+    def test_no_max_attempts(self):
+        module = CapaFactory.create(max_attempts='')
+        html = module.get_problem_html()
+        # assert that we got here without exploding
+
+
     def test_get_problem_html(self):
         module = CapaFactory.create()
 
@@ -797,7 +805,7 @@ class CapaModuleTest(unittest.TestCase):
         module.should_show_reset_button = Mock(return_value=show_reset_button)
         module.should_show_save_button = Mock(return_value=show_save_button)
 
-        # Mock the system rendering function 
+        # Mock the system rendering function
         module.system.render_template = Mock(return_value="<div>Test Template HTML</div>")
 
         # Patch the capa problem's HTML rendering
@@ -809,7 +817,7 @@ class CapaModuleTest(unittest.TestCase):
 
             # Also render the problem encapsulated in a <div>
             html_encapsulated = module.get_problem_html(encapsulate=True)
-            
+
         # Expect that we get the rendered template back
         self.assertEqual(html, "<div>Test Template HTML</div>")
 
@@ -831,7 +839,7 @@ class CapaModuleTest(unittest.TestCase):
 
 
     def test_get_problem_html_error(self):
-        """ 
+        """
         In production, when an error occurs with the problem HTML
         rendering, a "dummy" problem is created with an error
         message to display to the user.
@@ -845,10 +853,10 @@ class CapaModuleTest(unittest.TestCase):
         # is asked to render itself as HTML
         module.lcp.get_html = Mock(side_effect=Exception("Test"))
 
-        # Stub out the test_system rendering function 
+        # Stub out the test_system rendering function
         module.system.render_template = Mock(return_value="<div>Test Template HTML</div>")
 
-        # Turn off DEBUG 
+        # Turn off DEBUG
         module.system.DEBUG = False
 
         # Try to render the module with DEBUG turned off
@@ -860,4 +868,4 @@ class CapaModuleTest(unittest.TestCase):
         self.assertTrue("error" in context['problem']['html'])
 
         # Expect that the module has created a new dummy problem with the error
-        self.assertNotEqual(original_problem, module.lcp) 
+        self.assertNotEqual(original_problem, module.lcp)