FluentAssertions:如何在每对元素上使用自定义比较来比较两个集合? [英] FluentAssertions: How to compare two collections using a custom comparison on each pair of elements?
本文介绍了FluentAssertions:如何在每对元素上使用自定义比较来比较两个集合?的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
给定以下输入:
var customers = new[] {
new Customer { Name = "John", Age = 42 },
new Customer { Name = "Mary", Age = 43 }
};
var employees = new[] {
new Employee { FirstName = "John", Age = 42 },
new Employee { FirstName = "Mary", Age = 43 }
};
使用FluentAssertions比较这些列表的最佳方式是什么?
我目前唯一的方法是这样--非常类似于Enumerable.SequenceEqual:
using (var customerEnumerator = customers.GetEnumerator())
using (var employeeEnumerator = employees.GetEnumerator())
{
while (customerEnumerator.MoveNext())
{
employeeEnumerator.MoveNext().Should().BeTrue();
var (customer, employee) = (customerEnumerator.Current, employee.Current);
customer.Name.Should().BeEquivalentTo(employee.FirstName);
customer.Age.Should().Be(employee.Age);
}
employeeEnumerator.MoveNext().Should().BeFalse();
}
当然,这既不容易阅读,也不能提供FA通常质量的诊断输出。是否有内置的FluentAssertions方法来进行此断言?
推荐答案
改进断言的一种方法是将比较提取到自定义IEquivalencyStep
中,以指导应该如何比较Customer
和Employee
。
它由两部分组成:
CanHandle
确定何时适用此比较,以及Handle
执行自定义比较。
public class CustomerEmployeeComparer : IEquivalencyStep
{
public bool CanHandle(IEquivalencyValidationContext context,
IEquivalencyAssertionOptions config)
{
return context.Subject is Customer
&& context.Expectation is Employee;
}
public bool Handle(IEquivalencyValidationContext context, IEquivalencyValidator
parent, IEquivalencyAssertionOptions config)
{
var customer = (Customer)context.Subject;
var employee = (Employee)context.Expectation;
customer.Name.Should().Be(employee.FirstName, context.Because, context.BecauseArgs);
customer.Age.Should().Be(employee.Age, context.Because, context.BecauseArgs);
return true;
}
}
要在断言中使用CustomerEmployeeComparer
,请通过在BeEquivalentTo
的EquivalencyAssertionOptions config
参数上调用Using(new CustomerEmployeeComparer())
来添加它。
注意:由于您的示例要求按顺序比较这两个列表,因此我已将WithStrictOrdering()
添加到下面的示例中。
[TestMethod]
public void CompareCustomersAndEmployeesWithCustomEquivalencyStep()
{
// Arrange
var customers = new[] {
new Customer { Name = "John", Age = 42 },
new Customer { Name = "Mary", Age = 43 }
};
var employees = new[] {
new Employee { FirstName = "John", Age = 42 },
new Employee { FirstName = "Mary", Age = 43 }
};
// Act / Assert
customers.Should().BeEquivalentTo(employees, opt => opt
.Using(new CustomerEmployeeComparer())
.WithStrictOrdering());
}
public class Employee
{
public string FirstName { get; set; }
public int Age { get; set; }
}
public class Customer
{
public string Name { get; set; }
public int Age { get; set; }
}
将第一个Employee
的名称更改为Jonathan,现在会显示以下失败消息:
Message: Expected item[0] to be "Jonathan" with a length of 8, but "John" has a length of 4, differs near "hn" (index 2).
With configuration:
- Use declared types and members
- Compare enums by value
- Include all non-private properties
- Include all non-private fields
- Match member by name (or throw)
- Without automatic conversion.
- UnitTestProject15.CustomerEmployeeComparer
- Without automatic conversion.
- Always be strict about the collection order
对于任何感兴趣的人来说,有一个相关的未决问题,即覆盖要比较的属性。 https://github.com/fluentassertions/fluentassertions/issues/535
这篇关于FluentAssertions:如何在每对元素上使用自定义比较来比较两个集合?的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!
查看全文