#!/usr/bin/env python
# coding: utf-8

# In[4]:


xml="""
<quiz>
<!-- question: 850758  -->
  <question type="coderunner">
    <name>
      <text>How many items in a list?</text>
    </name>
    <questiontext format="html">
      <text><![CDATA[<p>Write a function <code>how_many(list_in)</code> which returns the number of items in <code>list_in</code>.</p>
<p><br></p>]]></text>
    </questiontext>
    <generalfeedback format="html">
      <text><![CDATA[<p><b>len() </b>returns the length (the number of items) of an object. The argument may be a sequence (such as a string, bytes, tuple, list, or range) or a collection (such as a dictionary, set, or frozen set).<br></p>]]></text>
    </generalfeedback>
    <defaultgrade>1</defaultgrade>
    <penalty>0</penalty>
    <hidden>0</hidden>
    <idnumber></idnumber>
    <coderunnertype>python3</coderunnertype>
    <prototypetype>0</prototypetype>
    <allornothing>1</allornothing>
    <penaltyregime>10, 20, ...</penaltyregime>
    <precheck>0</precheck>
    <showsource>0</showsource>
    <answerboxlines>6</answerboxlines>
    <answerboxcolumns>100</answerboxcolumns>
    <answerpreload>def how_many(list_in):
    '''returns the number of elements in list_in'''
    </answerpreload>
    <globalextra></globalextra>
    <useace></useace>
    <resultcolumns></resultcolumns>
    <template></template>
    <iscombinatortemplate></iscombinatortemplate>
    <allowmultiplestdins></allowmultiplestdins>
    <answer>def how_many(list_in):
    '''returns the number of elements in list_in'''
    return len(list_in)</answer>
    <validateonsave>1</validateonsave>
    <testsplitterre></testsplitterre>
    <language></language>
    <acelang></acelang>
    <sandbox></sandbox>
    <grader></grader>
    <cputimelimitsecs></cputimelimitsecs>
    <memlimitmb></memlimitmb>
    <sandboxparams></sandboxparams>
    <templateparams></templateparams>
    <hoisttemplateparams>1</hoisttemplateparams>
    <twigall>0</twigall>
    <uiplugin></uiplugin>
    <attachments>0</attachments>
    <attachmentsrequired>0</attachmentsrequired>
    <maxfilesize>10240</maxfilesize>
    <filenamesregex></filenamesregex>
    <filenamesexplain></filenamesexplain>
    <displayfeedback>1</displayfeedback>
    <testcases>
      <testcase testtype="0" useasexample="1" hiderestiffail="0" mark="1.0000000" >
      <testcode>
                <text>print ( how_many(['fig', 'kiwi', 13.7]))</text>
      </testcode>
      <stdin>
                <text></text>
      </stdin>
      <expected>
                <text>3</text>
      </expected>
      <extra>
                <text></text>
      </extra>
      <display>
                <text>SHOW</text>
      </display>
    </testcase>
      <testcase testtype="0" useasexample="0" hiderestiffail="0" mark="1.0000000" >
      <testcode>
                <text>print(how_many([]))</text>
      </testcode>
      <stdin>
                <text></text>
      </stdin>
      <expected>
                <text>0 </text>
      </expected>
      <extra>
                <text></text>
      </extra>
      <display>
                <text>SHOW</text>
      </display>
    </testcase>
      <testcase testtype="0" useasexample="0" hiderestiffail="0" mark="1.0000000" >
      <testcode>
                <text>print(how_many([' ']))</text>
      </testcode>
      <stdin>
                <text></text>
      </stdin>
      <expected>
                <text>1</text>
      </expected>
      <extra>
                <text></text>
      </extra>
      <display>
                <text>SHOW</text>
      </display>
    </testcase>
      <testcase testtype="0" useasexample="1" hiderestiffail="0" mark="1.0000000" >
      <testcode>
                <text>print(how_many([['only', 'count'], ['the' 'top'], ['level', 'lists']]))</text>
      </testcode>
      <stdin>
                <text></text>
      </stdin>
      <expected>
                <text>3</text>
      </expected>
      <extra>
                <text></text>
      </extra>
      <display>
                <text>SHOW</text>
      </display>
    </testcase>
      <testcase testtype="0" useasexample="0" hiderestiffail="0" mark="1.0000000" >
      <testcode>
                <text>print(how_many([1, [2, 3, [4, 5], 6], 7]))</text>
      </testcode>
      <stdin>
                <text></text>
      </stdin>
      <expected>
                <text>3</text>
      </expected>
      <extra>
                <text></text>
      </extra>
      <display>
                <text>SHOW</text>
      </display>
    </testcase>
    </testcases>
  </question>

</quiz>
"""


# In[5]:


import xml.etree.ElementTree as ET


root = ET.fromstring(xml)
root


# In[7]:


root.tag


# In[9]:


for child in root:
    print(child.tag, child.attrib)
    for gchild in child:
        print(gchild.tag, gchild.attrib)


# In[31]:


from IPython.display import HTML
for question in root.findall('question'):
    display(HTML(question.find('questiontext/text').text))
    answer = question.find('answer').text
    print(answer)
    print()
    tests = question.find('testcases')
    for test in tests.findall('testcase'):
        print(test.find('testcode/text').text, test.find('expected/text').text)


# There are a couple of ways we can evaluate the code represented by the string, specifically using `eval()` or `exec()`.
# 
# - `exec()` doesn't return anything;
# - `eval()` returns the final value;

# In[32]:


exec(answer)


# In[33]:


how_many(['fig', 'kiwi', 13.7])


# In[122]:


get_ipython().run_cell_magic('capture', 'my_answer --no-stderr', "answers = []\nfor question in root.findall('question'):\n    tests = question.find('testcases')\n    for test in tests.findall('testcase'):\n        exec(test.find('testcode/text').text)\n        answers.append(test.find('expected/text').text)\n")


# The way the question is written and handled is really shonky... I suspect it gives all sorts of opportunities for false somethings?!

# In[124]:


my_answer.stdout, '\n'.join(answers)+'\n'


# In[57]:


my_answer.stdout, '\n'.join(answers)+'\n'


# If we try to do some simple assertion tests on evaluated code, things all go wrong... we need to to type checking, white space clearning (nut might whitespace be important?) etc etc.

# In[121]:


import re
    
for question in root.findall('question'):
    tests = question.find('testcases')
    for test in tests.findall('testcase'):
        _test = test.find('testcode/text').text
        print(_test, '..')
        matches = re.findall(r"print\s*\(\s*(.*)\s*\)", _test)
        if matches:
            print(matches[0])
            answer = eval(matches[0])
            
            #Hack the assertion so tests pass - this leads to a loss of information
            # and suggests there's something wrong with how answers are represented?
            assert str(answer) == test.find('expected/text').text.strip()


# ## Addenda - Possibly Useful Fragments

# In[112]:


#The following replicates the %%capture 

#https://stackoverflow.com/a/3906309/454773
import sys
from io import StringIO
import contextlib


@contextlib.contextmanager
def stdoutIO(stdout=None):
    old = sys.stdout
    if stdout is None:
        stdout = StringIO()
    sys.stdout = stdout
    yield stdout
    sys.stdout = old
    
with stdoutIO() as s:
    exec('print("hello")')
    
s.getvalue()