测试驱动开发（Django）14

Marvin_Kai

393人浏览 · 2019-02-25 20:58:50

Marvin_Kai · 2019-02-25 20:58:50 发布

第14章简单的表单

Django鼓励使用表单类验证用户输入和显示错误信息。

14.1 把验证逻辑移动到表单中

在Django中视图很复杂则说明代码异味。考虑如何把逻辑移动到表单或模型类中。

Django表单的功能：

可以处理用户输入并加以验证
可以在模板中使用，并且有不同的渲染以及错误消息
可以把数据存入数据库

14.1.1 使用单元测试探索表单API

lists/forms.py

from django import forms

class ItemForm(forms.Form):
    item_text = forms.CharField()

lists/tests/test_forms.py

from django.test import TestCase
from lists.forms import ItemForm

class ItemFormTest(TestCase):
    def test_form_renders_tem_text_input(self):
        form = ItemForm()
        self.fail(form.as_p())

测试：AssertionError: <p><label for="id_item_text">Item text:</label> <input type="text" name="item_text" required id="id_item_text" /></p>

lists/tests/test_forms.py

class ItemFormTest(TestCase):

    def test_form_item_input_has_placeholder_and_css_classes(self):
        form = ItemForm()
        self.assertIn('placeholder="Enter a to-do item"', form.as_p())
        self.assertIn('class="form-control input-lg"', form.as_p())

AssertionError: <p><label for="id_item_text">Item text:</label> <input type="text" name="item_text" required id="id_item_text" /></p>

lists/forms.py

    widget = forms.fields.TextInput(attrs={
        'placeholder': 'Enter a to-do item',
        'class':'form-control input-lg'
    })

AssertionError: 'placeholder="Enter a to-do item"' not found in '<p><label for="id_item_text">Item text:</label> <input type="text" name="item_text" required id="id_item_text" /></p>'

14.1.2 换用Django中的ModelForm类

表单可用通过Django提供的ModelForm类来重用已经在模型中定义好的验证规则。

from django import forms
from lists.models import Item


class ItemForm(forms.models.ModelForm):

    class Meta:
        model = Item        #指定表单应用模型
        fields = ('text',)   #使用字段

AssertionError: 'placeholder="Enter a to-do item"' not found in '<p><label for="id_text">Text:</label> <textarea name="text" cols="40" rows="10" required id="id_text">\n</textarea></p>'


class ItemForm(forms.models.ModelForm):
    class Meta:
        model = Item  # 指定表单应用模型
        fields = ('text',)  # 使用字段
        widgets = {
            'text': forms.fields.TextInput(
                attrs={
                    'placeholder': 'Enter a to-do item',
                    'class': 'form-control input-lg',
                }
            ),
        }

通过测试

14.1.3 测试和定制表单验证

lists/tests/test_forms.py增加用一个测试

def test_form_validation_for_blank_items(self):
    form = ItemForm(data={'text':''})
    form.save()

ValueError: The Item could not be created because the data didn't validate.

def test_form_validation_for_blank_items(self):
    form = ItemForm(data={'text':''})
    self.assertFalse(form.is_valid())
    self.assertEqual(
        form.errors['text'],
        ["You can't have an empty list item"]
    )

AssertionError: ['This field is required.'] != ["You can't have an empty list item"]

那就修改默认错误提示

lists/forms.py

class Meta:
    model = Item  # 指定表单应用模型
    fields = ('text',)  # 使用字段
    widgets = {
        'text': forms.fields.TextInput(
            attrs={
                'placeholder': 'Enter a to-do item',
                'class': 'form-control input-lg',
            }
        ),
    }
    error_messages = {
        'text':{'required':"You can't have an empty list item"}
    }

通过测试

使用常量避免错误消息搅乱代码

EMPTY_ITEM_ERROR = "You can't have an empty list item"
[...]
        error_messages = {
            'text':{'required':EMPTY_ITEM_ERROR}
        }

修改测试

from lists.forms import ItemForm,EMPTY_ITEM_ERROR
[...]
        self.assertEqual(
            form.errors['text'],[EMPTY_ITEM_ERROR]  
        )

通过测试

提交： git commit -am 'new form for list items'

14.2 在视图中使用这个表单

14.2.1 在处理GET请求的视图中使用这个表单

lists/tests/test_views.py

from lists.forms import ItemForm


class HomePageTest(TestCase):

    def test_use_home_template(self):
        response = self.client.get('/')
        self.assertTemplateUsed(response, 'home.html')
    def test_home_page_uses_item_form(self):
        response = self.client.get('/')
        self.assertIsInstance(response.context['form'],ItemForm)

测试结果：KeyError: 'form'

修改视图：

from lists.forms import ItemForm


def home_page(request):
    return render(request, 'home.html',{'form':ItemForm()})

替换base.html input

<form method="POST" action="{% block form_action %}{% endblock %}">
    {% csrf_token %}
    {{ form.text }}
    {% if error %}

14.2.2 大量查找和替换

功能测试：selenium.common.exceptions.NoSuchElementException: Message: Unable to locate element: [id="id_new_item"]

提交以区分重命名和逻辑变动：git commit -am 'use new form in home_page,simplify tests. NB breaks stuff'

base.py 增加一个新辅助方法

def get_item_input_box(self):
    return self.browser.find_element_by_id('id_text')

使用get_item_input_box方法替换掉功能测试中id_new_item

grep -Ir item_text lists/ 找到之后替换为text

grep -r id_new_item lists/ 找到之后替换为id_text

通过单元测试

Ran 17 tests in 0.063s

功能测试：selenium.common.exceptions.NoSuchElementException: Message: Unable to locate element: [id="id_text"]

14.3 在POST请求的视图中使用这个表单

14.3.1 修改new_list视图的单元测试

lists/tests/test_views.py

分拆 test_validation_errors_are_sent_back_to_home_page_template方法

class NewListTest(TestCase):
    def test_for_invalid_input_renders_home_template(self):
        response = self.client.post('/lists/new', data={'text': ''})
        self.assertEqual(response.status_code, 200)
        self.assertTemplateUsed(response, 'home.html')

    def test_validation_errors_are_shown_on_home_page(self):
        response = self.client.post('/lists/new', data={'text': ''})
        self.assertContains(response, escape(EMPTY_ITEM_ERROR))

    def test_for_invalid_input_passes_form_to_template(self):
        response = self.client.post('/lists/new',data={'text':''})
        self.assertIsInstance(response.context['form'],ItemForm)

单元测试：

KeyError: 'form'

14.3.2 在视图中使用这个表单

视图：

def new_list(request):
    form = ItemForm(data=request.POST)
    if form.is_valid():
        list_ = List.objects.create()
        Item.objects.create(text=request.POST['text'], list=list_)
        return redirect(list_)
    else:
        return render(request, 'home.html', {'form': form})

单元测试：AssertionError: False is not true : Couldn't find 'You can't have an empty list item' in response

14.3.3 使用这个表单在模板中显示错误消息

base.html

<form method="POST" action="{% block form_action %}{% endblock %}">
    {% csrf_token %}
    {{ form.text }}
    {% if form.errors %}
        <div class="form-group has-error">
            <div class="help-block">{{ form.text.errors }}</div>
        </div>
    {% endif %}
</form>

单元测试：AssertionError: False is not true : Couldn't find 'You can't have an empty list item' in response

14.4 在其他视图中使用这个表单

lists/tests/test_views.py增加一个新的测试

class ListViewTest(TestCase):
[...]
    def test_displays_item_form(self):
        list_ = List.objects.create()
        response = self.client.get(f'/lists/{list_.id}/')
        self.assertIsInstance(response.context['form'], ItemForm)
        self.assertContains(response, 'name="text"')

KeyError: 'form' ,解决错误：修改视图

def view_list(request, list_id):
[...]
    form = ItemForm()
    return render(request, 'list.html', {'list': list_, 'form':form,'error': error})

14.4.1 定义辅助方法，简化测试

lists/tests/test_views.py

分拆test_validation_errors_end_up_on_lists_page方法

   def post_invalid_input(self):
        list_ = List.objects.create()
        return self.client.post(
            f'/lists/{list_.id}/',
            data={'text': ''}
        )

    def test_for_inwalid_input_noting_saved_to_db(self):
        self.post_invalid_input()
        self.assertEqual(Item.objects.count(), 0)

    def test_for_invalid_input_renders_list__template(self):
        response = self.post_invalid_input()
        self.assertEqual(response.status_code, 200)
        self.assertTemplateUsed(response, 'list.html')

    def test_for_invalid_input_passes_form_template(self):
        response = self.post_invalid_input()
        self.assertIsInstance(response.context['form'], ItemForm)

    def test_for_invalid_input_shows_error_on_page(self):
        response = self.post_invalid_input()
        self.assertContains(response, escape(EMPTY_ITEM_ERROR))

测试结果：AssertionError: False is not true : Couldn't find 'You can't have an empty list item' in response

视图：

def view_list(request, list_id):
    list_ = List.objects.get(id=list_id)
    error = None
    form = ItemForm(data=request.POST)
    if request.method == 'POST':
        form = ItemForm()
        if form.is_valid():
            Item.objects.create(text=request.POST['text'], list=list_)
            return redirect(list_)

    return render(request, 'list.html', {'list': list_, 'form': form})

单元测试：

Ran 23 tests in 0.085s

功能测试：selenium.common.exceptions.NoSuchElementException: Message: Unable to locate element: .has-error

14.4.2 意想不到的好处：HTML5自带的客户端验证

Django为输入框添加了required属性，HTML5的特性，浏览器会在客户端做验证，输入无效禁止提交表单。

python manage.py test functional_tests

Ran 4 tests in 43.807s

14.5 提交修改

git commit -am 'use form in all views, back to working state'

14.6 自定制错误并非无意义，因为并不是所有的浏览器都自带验证

14.7 使用表单自带的save方法

lists/tests/test_forms.py

def test_form_save_handles_saving_to_a_list(self):
    list_ = List.objects.create()
    form = ItemForm(data={'text':'do me'})
    new_item = form.save(for_list = list_)
    self.assertEqual(new_item,Item.objects.first())
    self.assertEqual(new_item.text,'do me')
    self.assertEqual(new_item.list,list_)

TypeError: save() got an unexpected keyword argument 'for_list'

lists/forms.py

def save(self, for_list):
    self.instance.list = for_list
    return super().save()

Ran 24 tests in 0.084s

修改视图：

def new_list(request):
    form = ItemForm(data=request.POST)
    if form.is_valid():
        list_ = List.objects.create()
        form.save(for_list=list_)
        return redirect(list_)
    else:
        return render(request, 'home.html', {'form': form})

Ran 24 tests in 0.084s

def view_list(request, list_id):
    list_ = List.objects.get(id=list_id)
    form = ItemForm()
    if request.method == 'POST':
        form = ItemForm(data=request.POST)
        if form.is_valid():
            form.save(for_list=list_)
            return redirect(list_)

    return render(request, 'list.html', {'list': list_, 'form': form})

Ran 24 tests in 0.083s

功能测试：

Ran 4 tests in 33.001s

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