如何为此 Django 自定义标签编写测试用例

Question

• Django 版本：v1.10
• Python：3.5（事实证明这很重要..看看答案）

我找到这个答案是为了有一个 if-else 标签来比较 Django 模板中的 request.path

https://stackoverflow.com/a/19895344/80353

from django import template
from django.template.base import Node, NodeList, TemplateSyntaxError

register = template.Library()

class IfCurrentViewNode(Node):
    child_nodelists = ('nodelist_true', 'nodelist_false')

    def __init__(self, view_name, nodelist_true, nodelist_false):
        self.view_name = view_name
        self.nodelist_true, self.nodelist_false = nodelist_true, nodelist_false

    def __repr__(self):
        return "<IfCurrentViewNode>"

    def render(self, context):
        view_name = self.view_name.resolve(context, True)
        request = context['request']
        if request.resolver_match.url_name == view_name:
            return self.nodelist_true.render(context)
        return self.nodelist_false.render(context)


def do_ifcurrentview(parser, token):
    bits = token.split_contents()
    if len(bits) < 2:
        raise TemplateSyntaxError("'%s' takes at least one argument"
                                  " (path to a view)" % bits[0])
    view_name = parser.compile_filter(bits[1])
    nodelist_true = parser.parse(('else', 'endifcurrentview'))
    token = parser.next_token()
    if token.contents == 'else':
        nodelist_false = parser.parse(('endifcurrentview',))
        parser.delete_first_token()
    else:
        nodelist_false = NodeList()
    return IfCurrentViewNode(view_name, nodelist_true, nodelist_false)

@register.tag
def ifcurrentview(parser, token):
    """
    Outputs the contents of the block if the current view match the argument.

    Examples::

        {% ifcurrentview 'path.to.some_view' %}
            ...
        {% endifcurrentview %}

        {% ifcurrentview 'path.to.some_view' %}
            ...
        {% else %}
            ...
        {% endifcurrentview %}
    """
    return do_ifcurrentview(parser, token)

想知道是否有办法编写测试用例来覆盖此自定义代码？

我想保持我们的测试覆盖率

Answer 1

如果不是全部，您应该能够使用 mock 覆盖大部分内容。例如，假设您要测试渲染功能：

from unittest.mock import Mock

def test_render_url_match(self):
    mock_request = Mock()
    matching_url_name = 'url_name'
    mock_nodelist_true, mock_nodelist_false = Mock(), Mock()
    mock_view_name = Mock()
    mock_view_name.resolve.return_value = matching_url_name
    mock_request.resolver_match.url_name = matching_url_name
    mock_context = {'request': mock_request}

    custom_node = IfCurrentViewNode(mock_view_name, mock_nodelist_true, mock_nodelist_false)
    custom_node.render(mock_context)

    # You can then test that the correct function was called:
    # you can change to `assert_called_once` if using Python 3.6
    mock_nodelist_true.render.assert_called_once_with(mock_context)

通过以这种方式设置模拟，我已确保 request.resolver_match.url_name == view_name 为真，并点击此行：return self.nodelist_true.render(context)。然后，您可以设置 url 名称，使它们不匹配并覆盖错误的情况。

然后，对于do_ifcurrentview 函数，您也可以模拟出您需要的任何部分。也许您不想让parser.compile_filter 返回您需要的东西。只需模拟它并更改返回值：

with mock.patch('parser.compile_filter') as mock_compile_filter:
    mock_compile_filter.return_value = 'my_expected_view_name'