我的模型中有ManyToMany字段，我以仅为此目的创建的ModelForm形式为其编写了自定义验证。验证工作正常，但我不知道如何正确编写单元测试。
#models.py
class Course(models.Model):
# some code
max_number_of_students = models.PositiveSmallIntegerField(
default=30)
class ClassOccurrence(models.Model):
course = models.ForeignKey(Course, on_delete=models.CASCADE)
students = models.ManyToManyField(User, blank=True)
# some code
# forms.py
class ClassOccurrenceForm(forms.ModelForm):
# some code
def clean(self):
# Checks if number of students inscribed is not greater than allowed
# for the course
cleaned_data = super(ClassOccurrenceForm, self).clean()
students = cleaned_data.get('students')
course = cleaned_data.get('course')
if students and course:
if students.count() > course.max_number_of_students:
raise ValidationError({
'students': "Too many students!})
return cleaned_data
问题出在这部分：
# tests.py
# some code
def test_clean_number_of_students_smaller_than_max_students_number(self):
self.course_0.max_number_of_students = 5
self.course_0.save()
users = UserFactory.create_batch(10)
self.assertRaises(ValidationError, self.class_occurrence_0.students.add(*users))
try:
self.class_occurrence_0.students.add(*users)
except ValidationError as e:
self.assertEqual(e.errors, {'students': ["Too many students!"]})
当前它无法按预期运行。在测试方法中，似乎没有在应该引发的地方引发ValidationError。有人可以帮我修复它吗？
答案 0 :(得分：0)
这似乎可行：
<html>
<head>
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css" integrity="sha384-ggOyR0iXCbMQv3Xipma34MD+dH/1fQ784/j6cY/iJTQUOhcWr7x9JvoRxT2MZw1T" crossorigin="anonymous">
</head>
<body>
<div class="container-fluid">
<div class="row">
<div class="col-12">
<!-- Inizio -->
<div id="carouselExampleCaptions" class="carousel slide" data-ride="carousel">
<ol class="carousel-indicators">
<li data-target="#carouselExampleCaptions" data-slide-to="0" class=""></li>
<li data-target="#carouselExampleCaptions" data-slide-to="1" class=""></li>
<li data-target="#carouselExampleCaptions" data-slide-to="2" class="active"></li>
</ol>
<div class="carousel-inner">
<div class="carousel-item">
<img class="d-block w-100" data-src="holder.js/800x400?auto=yes&bg=777&fg=555&text=First slide" alt="First slide [800x400]" src="data:image/svg+xml;charset=UTF-8,%3Csvg%20width%3D%22800%22%20height%3D%22400%22%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20viewBox%3D%220%200%20800%20400%22%20preserveAspectRatio%3D%22none%22%3E%3Cdefs%3E%3Cstyle%20type%3D%22text%2Fcss%22%3E%23holder_16be736b2af%20text%20%7B%20fill%3A%23555%3Bfont-weight%3Anormal%3Bfont-family%3AHelvetica%2C%20monospace%3Bfont-size%3A40pt%20%7D%20%3C%2Fstyle%3E%3C%2Fdefs%3E%3Cg%20id%3D%22holder_16be736b2af%22%3E%3Crect%20width%3D%22800%22%20height%3D%22400%22%20fill%3D%22%23777%22%3E%3C%2Frect%3E%3Cg%3E%3Ctext%20x%3D%22285.921875%22%20y%3D%22217.7609375%22%3EFirst%20slide%3C%2Ftext%3E%3C%2Fg%3E%3C%2Fg%3E%3C%2Fsvg%3E"
data-holder-rendered="true">
<div class="carousel-caption d-none d-block">
<h5>(1) This text should <br/> slide in front of <br/> the dog image</h5>
</div>
</div>
<div class="carousel-item">
<img class="d-block w-100" data-src="holder.js/800x400?auto=yes&bg=666&fg=444&text=Second slide" alt="Second slide [800x400]" src="data:image/svg+xml;charset=UTF-8,%3Csvg%20width%3D%22800%22%20height%3D%22400%22%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20viewBox%3D%220%200%20800%20400%22%20preserveAspectRatio%3D%22none%22%3E%3Cdefs%3E%3Cstyle%20type%3D%22text%2Fcss%22%3E%23holder_16be736b2b3%20text%20%7B%20fill%3A%23444%3Bfont-weight%3Anormal%3Bfont-family%3AHelvetica%2C%20monospace%3Bfont-size%3A40pt%20%7D%20%3C%2Fstyle%3E%3C%2Fdefs%3E%3Cg%20id%3D%22holder_16be736b2b3%22%3E%3Crect%20width%3D%22800%22%20height%3D%22400%22%20fill%3D%22%23666%22%3E%3C%2Frect%3E%3Cg%3E%3Ctext%20x%3D%22247.3125%22%20y%3D%22217.7609375%22%3ESecond%20slide%3C%2Ftext%3E%3C%2Fg%3E%3C%2Fg%3E%3C%2Fsvg%3E"
data-holder-rendered="true">
<div style="" class="carousel-caption d-none d-block">
<h5>(2) This text should <br/> slide in front of <br/> the dog image</h5>
</div>
</div>
<div class="carousel-item active">
<img class="d-block w-100" data-src="holder.js/800x400?auto=yes&bg=555&fg=333&text=Third slide" alt="Third slide [800x400]" src="data:image/svg+xml;charset=UTF-8,%3Csvg%20width%3D%22800%22%20height%3D%22400%22%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20viewBox%3D%220%200%20800%20400%22%20preserveAspectRatio%3D%22none%22%3E%3Cdefs%3E%3Cstyle%20type%3D%22text%2Fcss%22%3E%23holder_16be736b2b4%20text%20%7B%20fill%3A%23333%3Bfont-weight%3Anormal%3Bfont-family%3AHelvetica%2C%20monospace%3Bfont-size%3A40pt%20%7D%20%3C%2Fstyle%3E%3C%2Fdefs%3E%3Cg%20id%3D%22holder_16be736b2b4%22%3E%3Crect%20width%3D%22800%22%20height%3D%22400%22%20fill%3D%22%23555%22%3E%3C%2Frect%3E%3Cg%3E%3Ctext%20x%3D%22277%22%20y%3D%22217.7609375%22%3EThird%20slide%3C%2Ftext%3E%3C%2Fg%3E%3C%2Fg%3E%3C%2Fsvg%3E"
data-holder-rendered="true">
<div class="carousel-caption d-none d-block">
<h5>(3) This text should <br/> slide in front of <br/> the dog image</h5>
</div>
</div>
<div class="dog" style="position: relative; top: 30px; left:10px;">
<!--<img src="https://picsum.photos/id/237/120/180" />-->
</div>
</div>
<a class="carousel-control-prev" href="#carouselExampleCaptions" role="button" data-slide="prev">
<span class="carousel-control-prev-icon" aria-hidden="true"></span>
<span class="sr-only">Previous</span>
</a>
<a class="carousel-control-next" href="#carouselExampleCaptions" role="button" data-slide="next">
<span class="carousel-control-next-icon" aria-hidden="true"></span>
<span class="sr-only">Next</span>
</a>
</div>
<!-- Fine -->
</div>
</div>
</div>
<script src="https://code.jquery.com/jquery-3.3.1.slim.min.js" integrity="sha384-q8i/X+965DzO0rT7abK41JStQIAqVgRVzpbzo5smXKp4YfRvH+8abtTE1Pi6jizo" crossorigin="anonymous"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.7/umd/popper.min.js" integrity="sha384-UO2eT0CpHqdSJQ6hJty5KVphtPhzWj9WO1clHTMGa3JDZwrnQq4sF86dIHNDz0W1" crossorigin="anonymous"></script>
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/js/bootstrap.min.js" integrity="sha384-JjSmVgyd0p3pXB1rRibZUAYoIIy6OrQ6VrjIEaFf/nJGzIxFDsf4x0xIM+B07jRM" crossorigin="anonymous"></script>
</body>
</html>