Cleanups:

 - switch to using registry
 - pull math and solution "input types" into a separate customrender.py file
 - make capa_problem use new custom renderers and input types registries
 - remove unused imports, methods, etc
 - add tests for math and solution tags.

common/lib/capa/capa/capa_problem.py

@@ -38,6 +38,7 @@ import calc
 from correctmap import CorrectMap
 import eia
 import inputtypes
+import customrender
 from util import contextualize_text, convert_files_to_filenames
 import xqueue_interface
 
@@ -47,23 +48,8 @@ import responsetypes
 # dict of tagname, Response Class -- this should come from auto-registering
 response_tag_dict = dict([(x.response_tag, x) for x in responsetypes.__all__])
 
-# Different ways students can input code
-entry_types = ['textline',
-               'schematic',
-               'textbox',
-               'imageinput',
-               'optioninput',
-               'choicegroup',
-               'radiogroup',
-               'checkboxgroup',
-               'filesubmission',
-               'javascriptinput',
-               'crystallography',
-               'chemicalequationinput',
-               'vsepr_input']
-
 # extra things displayed after "show answers" is pressed
-solution_types = ['solution']
+solution_tags = ['solution']
 
 # these get captured as student responses
 response_properties = ["codeparam", "responseparam", "answer"]
@@ -309,7 +295,7 @@ class LoncapaProblem(object):
             answer_map.update(results)
 
         # include solutions from <solution>...</solution> stanzas
-        for entry in self.tree.xpath("//" + "|//".join(solution_types)):
+        for entry in self.tree.xpath("//" + "|//".join(solution_tags)):
             answer = etree.tostring(entry)
             if answer:
                 answer_map[entry.get('id')] = contextualize_text(answer, self.context)
@@ -487,7 +473,7 @@ class LoncapaProblem(object):
 
         problemid = problemtree.get('id')    # my ID
 
-        if problemtree.tag in inputtypes.registered_input_tags():
+        if problemtree.tag in inputtypes.registry.registered_tags():
             # If this is an inputtype subtree, let it render itself.
             status = "unsubmitted"
             msg = ''
@@ -513,7 +499,7 @@ class LoncapaProblem(object):
                                 'hint': hint,
                                 'hintmode': hintmode,}}
 
-            input_type_cls = inputtypes.get_class_for_tag(problemtree.tag)
+            input_type_cls = inputtypes.registry.get_class_for_tag(problemtree.tag)
             the_input = input_type_cls(self.system, problemtree, state)
             return the_input.get_html()
 
@@ -521,9 +507,15 @@ class LoncapaProblem(object):
         if problemtree in self.responders:
             return self.responders[problemtree].render_html(self._extract_html)
 
+        # let each custom renderer render itself:
+        if problemtree.tag in customrender.registry.registered_tags():
+            renderer_class = customrender.registry.get_class_for_tag(problemtree.tag)
+            renderer = renderer_class(self.system, problemtree)
+            return renderer.get_html()
+
+        # otherwise, render children recursively, and copy over attributes
         tree = etree.Element(problemtree.tag)
         for item in problemtree:
-            # render child recursively
             item_xhtml = self._extract_html(item)
             if item_xhtml is not None:
                     tree.append(item_xhtml)
@@ -560,11 +552,12 @@ class LoncapaProblem(object):
             response_id += 1
 
             answer_id = 1
+            input_tags = inputtypes.registry.registered_tags()
             inputfields = tree.xpath("|".join(['//' + response.tag + '[@id=$id]//' + x
-                                               for x in (entry_types + solution_types)]),
+                                               for x in (input_tags + solution_tags)]),
                                     id=response_id_str)
 
-            # assign one answer_id for each entry_type or solution_type
+            # assign one answer_id for each input type or solution type
             for entry in inputfields:
                 entry.attrib['response_id'] = str(response_id)
                 entry.attrib['answer_id'] = str(answer_id)

common/lib/capa/capa/customrender.py

+"""
+This has custom renderers: classes that know how to render certain problem tags (e.g. <math> and
+<solution>) to html.
+
+These tags do not have state, so they just get passed the system (for access to render_template),
+and the xml element.
+"""
+
+from registry import TagRegistry
+
+import logging
+import re
+import shlex  # for splitting quoted strings
+import json
+
+from lxml import etree
+import xml.sax.saxutils as saxutils
+from registry import TagRegistry
+
+log = logging.getLogger('mitx.' + __name__)
+
+registry = TagRegistry()
+
+#-----------------------------------------------------------------------------
+class MathRenderer(object):
+    tags = ['math']
+
+    def __init__(self, system, xml):
+        '''
+        Render math using latex-like formatting.
+
+        Examples:
+
+        <math>$\displaystyle U(r)=4 U_0 $</math>
+        <math>$r_0$</math>
+
+        We convert these to [mathjax]...[/mathjax] and [mathjaxinline]...[/mathjaxinline]
+
+        TODO: use shorter tags (but this will require converting problem XML files!)
+        '''
+        self.system = system
+        self.xml = xml
+
+        mathstr = re.sub('\$(.*)\$', r'[mathjaxinline]\1[/mathjaxinline]', xml.text)
+        mtag = 'mathjax'
+        if not r'\displaystyle' in mathstr:
+            mtag += 'inline'
+        else:
+            mathstr = mathstr.replace(r'\displaystyle', '')
+        self.mathstr = mathstr.replace('mathjaxinline]', '%s]' % mtag)
+
+
+    def get_html(self):
+        """
+        Return the contents of this tag, rendered to html, as an etree element.
+        """
+        # TODO: why are there nested html tags here??  Why are there html tags at all, in fact?
+        html = '<html><html>%s</html><html>%s</html></html>' % (
+            self.mathstr, saxutils.escape(self.xml.tail))
+        try:
+            xhtml = etree.XML(html)
+        except Exception as err:
+            if self.system.DEBUG:
+                msg = '<html><div class="inline-error"><p>Error %s</p>' % (
+                    str(err).replace('<', '&lt;'))
+                msg += ('<p>Failed to construct math expression from <pre>%s</pre></p>' %
+                        html.replace('<', '&lt;'))
+                msg += "</div></html>"
+                log.error(msg)
+                return etree.XML(msg)
+            else:
+                raise
+        return xhtml
+
+
+registry.register(MathRenderer)
+
+#-----------------------------------------------------------------------------
+
+class SolutionRenderer(object):
+    '''
+    A solution is just a <span>...</span> which is given an ID, that is used for displaying an
+    extended answer (a problem "solution") after "show answers" is pressed.
+
+    Note that the solution content is NOT rendered and returned in the HTML. It is obtained by an
+    ajax call.
+    '''
+    tags = ['solution']
+
+    def __init__(self, system, xml):
+        self.system = system
+        self.id = xml.get('id')
+
+    def get_html(self):
+        context = {'id': self.id}
+        html = self.system.render_template("solutionspan.html", context)
+        return etree.XML(html)
+
+registry.register(SolutionRenderer)
+

common/lib/capa/capa/tests/__init__.py

@@ -4,13 +4,23 @@ import os
 
 from mock import Mock
 
+import xml.sax.saxutils as saxutils
+
 TEST_DIR = os.path.dirname(os.path.realpath(__file__))
 
+def tst_render_template(template, context):
+    """
+    A test version of render to template.  Renders to the repr of the context, completely ignoring
+    the template name.  To make the output valid xml, quotes the content, and wraps it in a <div>
+    """
+    return '<div>{0}</div>'.format(saxutils.escape(repr(context)))
+
+
 test_system = Mock(
     ajax_url='courses/course_id/modx/a_location',
     track_function=Mock(),
     get_module=Mock(),
-    render_template=Mock(),
+    render_template=tst_render_template,
     replace_urls=Mock(),
     user=Mock(),
     filestore=fs.osfs.OSFS(os.path.join(TEST_DIR, "test_files")),

common/lib/capa/capa/tests/test_customrender.py

+from lxml import etree
+import unittest
+import xml.sax.saxutils as saxutils
+
+from . import test_system
+from capa import customrender
+
+# just a handy shortcut
+lookup_tag = customrender.registry.get_class_for_tag
+
+def extract_context(xml):
+    """
+    Given an xml element corresponding to the output of test_system.render_template, get back the
+    original context
+    """
+    return eval(xml.text)
+
+def quote_attr(s):
+    return saxutils.quoteattr(s)[1:-1]  # don't want the outer quotes
+
+class HelperTest(unittest.TestCase):
+    '''
+    Make sure that our helper function works!
+    '''
+    def check(self, d):
+        xml = etree.XML(test_system.render_template('blah', d))
+        self.assertEqual(d, extract_context(xml))
+
+    def test_extract_context(self):
+        self.check({})
+        self.check({1, 2})
+        self.check({'id', 'an id'})
+        self.check({'with"quote', 'also"quote'})
+
+
+class SolutionRenderTest(unittest.TestCase):
+    '''
+    Make sure solutions render properly.
+    '''
+
+    def test_rendering(self):
+        solution = 'To compute unicorns, count them.'
+        xml_str = """<solution id="solution_12">{s}</solution>""".format(s=solution)
+        element = etree.fromstring(xml_str)
+
+        renderer = lookup_tag('solution')(test_system, element)
+
+        self.assertEqual(renderer.id, 'solution_12')
+
+        # our test_system "renders" templates to a div with the repr of the context
+        xml = renderer.get_html()
+        context = extract_context(xml)
+        self.assertEqual(context, {'id' : 'solution_12'})
+
+
+class MathRenderTest(unittest.TestCase):
+    '''
+    Make sure math renders properly.
+    '''
+
+    def check_parse(self, latex_in, mathjax_out):
+        xml_str = """<math>{tex}</math>""".format(tex=latex_in)
+        element = etree.fromstring(xml_str)
+
+        renderer = lookup_tag('math')(test_system, element)
+
+        self.assertEqual(renderer.mathstr, mathjax_out)
+    
+    def test_parsing(self):
+        self.check_parse('$abc$', '[mathjaxinline]abc[/mathjaxinline]')
+        self.check_parse('$abc', '$abc')
+        self.check_parse(r'$\displaystyle 2+2$', '[mathjax] 2+2[/mathjax]')
+        
+
+    # NOTE: not testing get_html yet because I don't understand why it's doing what it's doing.
+        

common/lib/capa/capa/tests/test_inputtypes.py

 """
-Tests of input types (and actually responsetypes too).
+Tests of input types.
 
 TODO:
 - test unicode in values, parameters, etc.
@@ -7,27 +7,16 @@ TODO:
 - test funny xml chars -- should never get xml parse error if things are escaped properly.
 """
 
-from datetime import datetime
-import json
-from mock import Mock
-from nose.plugins.skip import SkipTest
-import os
+from lxml import etree
 import unittest
 import xml.sax.saxutils as saxutils
 
 from . import test_system
 from capa import inputtypes
 
-from lxml import etree
-
-def tst_render_template(template, context):
-    """
-    A test version of render to template.  Renders to the repr of the context, completely ignoring the template name.
-    """
-    return repr(context)
-
+# just a handy shortcut
+lookup_tag = inputtypes.registry.get_class_for_tag
 
-system = Mock(render_template=tst_render_template)
 
 def quote_attr(s):
     return saxutils.quoteattr(s)[1:-1]  # don't want the outer quotes
@@ -44,7 +33,7 @@ class OptionInputTest(unittest.TestCase):
         state = {'value': 'Down',
                  'id': 'sky_input',
                  'status': 'answered'}
-        option_input = inputtypes.get_class_for_tag('optioninput')(system, element, state)
+        option_input = lookup_tag('optioninput')(test_system, element, state)
 
         context = option_input._get_render_context()
 
@@ -80,7 +69,7 @@ class ChoiceGroupTest(unittest.TestCase):
                      'id': 'sky_input',
                      'status': 'answered'}
 
-            option_input = inputtypes.get_class_for_tag('choicegroup')(system, element, state)
+            option_input = lookup_tag('choicegroup')(test_system, element, state)
 
             context = option_input._get_render_context()
 
@@ -119,7 +108,7 @@ class ChoiceGroupTest(unittest.TestCase):
                  'id': 'sky_input',
                  'status': 'answered'}
 
-        the_input = inputtypes.get_class_for_tag(tag)(system, element, state)
+        the_input = lookup_tag(tag)(test_system, element, state)
 
         context = the_input._get_render_context()
 
@@ -164,7 +153,7 @@ class JavascriptInputTest(unittest.TestCase):
         element = etree.fromstring(xml_str)
 
         state = {'value': '3',}
-        the_input = inputtypes.get_class_for_tag('javascriptinput')(system, element, state)
+        the_input = lookup_tag('javascriptinput')(test_system, element, state)
 
         context = the_input._get_render_context()
 
@@ -191,7 +180,7 @@ class TextLineTest(unittest.TestCase):
         element = etree.fromstring(xml_str)
 
         state = {'value': 'BumbleBee',}
-        the_input = inputtypes.get_class_for_tag('textline')(system, element, state)
+        the_input = lookup_tag('textline')(test_system, element, state)
 
         context = the_input._get_render_context()
 
@@ -219,7 +208,7 @@ class TextLineTest(unittest.TestCase):
         element = etree.fromstring(xml_str)
 
         state = {'value': 'BumbleBee',}
-        the_input = inputtypes.get_class_for_tag('textline')(system, element, state)
+        the_input = lookup_tag('textline')(test_system, element, state)
 
         context = the_input._get_render_context()
 
@@ -260,7 +249,7 @@ class FileSubmissionTest(unittest.TestCase):
         state = {'value': 'BumbleBee.py',
                  'status': 'incomplete',
                  'feedback' : {'message': '3'}, }
-        the_input = inputtypes.get_class_for_tag('filesubmission')(system, element, state)
+        the_input = lookup_tag('filesubmission')(test_system, element, state)
 
         context = the_input._get_render_context()
 
@@ -304,7 +293,7 @@ class CodeInputTest(unittest.TestCase):
                  'status': 'incomplete',
                  'feedback' : {'message': '3'}, }
 
-        the_input = inputtypes.get_class_for_tag('codeinput')(system, element, state)
+        the_input = lookup_tag('codeinput')(test_system, element, state)
 
         context = the_input._get_render_context()
 
@@ -354,7 +343,7 @@ class SchematicTest(unittest.TestCase):
         state = {'value': value,
                  'status': 'unsubmitted'}
 
-        the_input = inputtypes.get_class_for_tag('schematic')(system, element, state)
+        the_input = lookup_tag('schematic')(test_system, element, state)
 
         context = the_input._get_render_context()
 
@@ -393,7 +382,7 @@ class ImageInputTest(unittest.TestCase):
         state = {'value': value,
                  'status': 'unsubmitted'}
 
-        the_input = inputtypes.get_class_for_tag('imageinput')(system, element, state)
+        the_input = lookup_tag('imageinput')(test_system, element, state)
 
         context = the_input._get_render_context()
 
@@ -447,7 +436,7 @@ class CrystallographyTest(unittest.TestCase):
         state = {'value': value,
                  'status': 'unsubmitted'}
 
-        the_input = inputtypes.get_class_for_tag('crystallography')(system, element, state)
+        the_input = lookup_tag('crystallography')(test_system, element, state)
 
         context = the_input._get_render_context()
 
@@ -476,7 +465,7 @@ class ChemicalEquationTest(unittest.TestCase):
         element = etree.fromstring(xml_str)
 
         state = {'value': 'H2OYeah',}
-        the_input = inputtypes.get_class_for_tag('chemicalequationinput')(system, element, state)
+        the_input = lookup_tag('chemicalequationinput')(test_system, element, state)
 
         context = the_input._get_render_context()