Initial imports and defines.
----
    >>> cfolder = portal.cfolder
    >>> cfolder_url = cfolder.absolute_url()
    >>> doc01 = portal.doc01
    >>> doc01_url = doc01.absolute_url()
    >>> cart_url = '{0}/@@cart'.format(portal_url)

Go to doc01
-----------
    >>> browser.open(doc01_url)
    >>> '<select id="quantity" name="quantity">' in browser.contents
    True
    >>> browser.getControl(name="quantity").value = ['2']
    >>> 'value="2" selected="selected"' in browser.contents
    False
    >>> browser.getControl(name="form.button.AddToCart").click()
    >>> browser.open(cart_url)
    >>> 'value="2" selected="selected"' in browser.contents
    True
    >>> browser.getControl(name="quantity").value = ['4']
    >>> 'value="4" selected="selected"' in browser.contents
    False
    >>> browser.getControl(name="form.button.UpdateCartContent").click()
    >>> 'value="4" selected="selected"' in browser.contents
    True

Log in and change the Quantity Method
--------------------------------------
    >>> from plone.app.testing import TEST_USER_NAME, TEST_USER_PASSWORD
    >>> browser.login(TEST_USER_NAME, TEST_USER_PASSWORD)
    >>> browser.open(cfolder_url)
    >>> browser.getLink('Edit').click()
    >>> browser.getControl(name="quantity_method").value = ['Input']
    >>> browser.getControl('Save').click()

Log out and got to Product01.
------------------------------
    >>> browser.open(doc01_url)
    >>> try:
    ...     browser.getControl(name="form.button.AddToCart").click()
    ... except:
    ...     print portal.error_log.getLogEntries()[0]['tb_text']
    ...     import pdb; pdb.set_trace()
    >>> browser.open(cart_url)
    >>> 'name="quantity" size="3" value="4"' in browser.contents
    True

    >>> browser.open(doc01_url)
    >>> browser.getControl(name="quantity").value = 'aaa'
    >>> try:
    ...     browser.getControl(name="form.button.AddToCart").click()
    ... except:
    ...     print portal.error_log.getLogEntries()[0]['tb_text']
    ...     import pdb; pdb.set_trace()
    >>> browser.open(cart_url)
    >>> 'name="quantity" size="3" value="4"' in browser.contents
    True

    >>> browser.open(doc01_url)
    >>> browser.getControl(name="quantity").value = '-5'
    >>> browser.getControl(name="form.button.AddToCart").click()
    >>> browser.open(cart_url)
    >>> 'name="quantity" size="3" value="4"' in browser.contents
    True

    >>> browser.open(doc01_url)
    >>> browser.getControl(name="quantity").value = '3'
    >>> browser.getControl(name="form.button.AddToCart").click()
    >>> browser.open(cart_url)
    >>> 'name="quantity" size="3" value="7"' in browser.contents
    True

    >>> browser.open(doc01_url)
    >>> browser.getControl(name="quantity").value = '4'
    >>> browser.getControl(name="form.button.AddToCart").click()
    >>> browser.open(cart_url)
    >>> 'name="quantity" size="3" value="10"' in browser.contents
    True

In the cart.
------------
    >>> browser.getControl(name="quantity").value = ''
    >>> browser.getControl(name="form.button.UpdateCartContent").click()
    >>> 'name="quantity" size="3" value="10"' in browser.contents
    True

    >>> browser.getControl(name="quantity").value = 'aaa'
    >>> browser.getControl(name="form.button.UpdateCartContent").click()
    >>> 'name="quantity" size="3" value="10"' in browser.contents
    True

    >>> browser.getControl(name="quantity").value = '-5'
    >>> browser.getControl(name="form.button.UpdateCartContent").click()
    >>> 'name="quantity" size="3" value="10"' in browser.contents
    True

    >>> browser.getControl(name="quantity").value = '11'
    >>> browser.getControl(name="form.button.UpdateCartContent").click()
    >>> 'name="quantity" size="3" value="10"' in browser.contents
    True

    >>> browser.getControl(name="quantity").value = '5'
    >>> browser.getControl(name="form.button.UpdateCartContent").click()
    >>> 'name="quantity" size="3" value="5"' in browser.contents
    True
