如何使用 Fluent Assertion 比较因属性而异的两个集合？

Question

我有 public class RuleInfo 是从内部创建的 class Rule.

private static RuleInfo CreateRuleInfo(Rule r)
{
    return new RuleInfo
    {
        RuleCode = r.RuleId,
        DisplayName = r.RuleCode,
        Description = r.Description,
        LegacyRuleCode = null
    };
}

它们的属性名称各不相同，因此 ShouldBeEquivalentTo() 或 ShouldAllBeEquivalentTo() 不起作用。

现在我正在比较它们manually/explicitly:

foreach (var x in Enumerable.Zip(infs, rules, (i, r) => new { Info = i, Rule = r }))
{
    x.Info.ShouldBeEquivalentTo(
        new
        {
            RuleCode = x.Rule.RuleId,
            DisplayName = x.Rule.RuleCode,
            Description = x.Rule.Description,
            LegacyRuleCode = (string)null
        });
}

是否有更好、更紧凑、更简洁、更易读的方式？

Answer 1

遗憾的是，当前无法在比较不同类型时指定属性之间的映射。关于它有一个开放的issue。

下面是比较两个集合的另一种方法的示例。请注意，我假设 == 执行值相等。因此，如果您所有的财产都是 int 和 string，那么您就安全到家了。

ruleInfos.Should().Equal(rules, (ruleInfo, rule) =>
    ruleInfo.RuleCode == rule.RuleId
     && ruleInfo.DisplayName == rule.RuleCode
    && ruleInfo.Description == rule.Description
);

例如没有重载 == 的引用类型，您需要优雅地处理空值，例如

(PropertyA == PropertyB) || (PropertyA?.Equals(PropertyB) == true

Answer 2

一个选项是向全局选项配置添加自定义等效步骤：

class DifferentObjectsEquivalencyStep<T1, T2> : IEquivalencyStep {
    private readonly Func<T1, T2> _converter;

    public DifferentObjectsEquivalencyStep(Func<T1, T2> converter) {
        _converter = converter;
    }

    public bool CanHandle(IEquivalencyValidationContext context, IEquivalencyAssertionOptions config) {
        return context.Subject is T1 && context.Expectation is T2 || context.Subject is T2 && context.Expectation is T1;
    }

    public bool Handle(IEquivalencyValidationContext context, IEquivalencyValidator parent, IEquivalencyAssertionOptions config) {            
        var first = context.Subject is T1 ? (T1) context.Subject : (T1) context.Expectation;
        var second = context.Subject is T2 ? (T2) context.Subject : (T2) context.Expectation;
        second.ShouldBeEquivalentTo(_converter(first));
        return true;
    }
}

然后在进行所有比较之前的某处：

AssertionOptions.AssertEquivalencyUsing(c => c.Using(
            new DifferentObjectsEquivalencyStep<Rule, RuleInfo>(CreateRuleInfo)));

之后，常规 ShouldBeEquivalentTo（和 ShouldAllBeEquivalentTo）将起作用：

rule.ShouldBeEquivalentTo(info);

如何使用 Fluent Assertion 比较因属性而异的两个集合？

How to compare two collections that vary by properties using Fluent Assertion?

c#

unit-testing

fluent-assertions