如何使用流利的断言比较对象图中的嵌套列表

Posted 2023-03-24

【中文标题】如何使用流利的断言比较对象图中的嵌套列表

【英文标题】：How to compare nested lists in object graphs using fluent assertions

【发布时间】：2016-10-27 00:06:21

【问题描述】：

如果我有一个包含列表的预期对象图，如下所示：

        var expectedExperiment = new Experiment
        
            Number= "12345",
            AllocatedInstrument = "Instrument 1",
            Experimenters = new List<Experimenter>
            
                new Experimenter
                
                    Name = "Sue"
                    Role = "Scientist",
                    Id = 1,
                    Initials = "S"
                ,
                new Experimenter()
                
                    Name = "Mark",
                    Role = "Technician",
                    Id = 2,
                    Initials = "M"
                ,
            
        ;

当我只想在子对象列表中包含某些属性时，如何将它与我的实际对象进行比较。

例如，我想写这样的东西来比较所有父对象的属性和一些子对象的属性：

        actualExperiment.ShouldBeEquivalentTo(expectedExperiment, options => options
            .Including(o => o.Number)
            .Including(o => o.AllocatedInstrument)
            .Including(o => o.Experimenters.Select(e => e.Role))
            .Including(o => o.Experimenters.Select(e => e.Name)));

但我得到一个例外：

System.ArgumentException : Expression <o.Experimenters.Select(e => e.Role)> cannot be used to select a member.

在这种情况下，我不介意子项的顺序，但我想断言我关心的属性符合预期。

【参考方案1】：

您可以通过检查当前对象的运行时类型和选定的成员路径来做到这一点：

.Including(subjectInfo => subjectInfo.RuntimeType == typeof(Experimenter) &&
                          subjectInfo.SelectedMemberPath.EndsWith("Role"))

这可以提取到一个方法中以供进一步重用：

private Expression<Func<ISubjectInfo, bool>> BuildMemberExpression<TSource, TProperty>(Expression<Func<TSource,TProperty>> propertySelector)
    
        var memberExpression = propertySelector.Body as MemberExpression;
        if (memberExpression == null)
        
            throw new NotSupportedException();
        

        return subjectInfo => subjectInfo.RuntimeType == typeof(TSource) && 
                              subjectInfo.SelectedMemberPath.EndsWith(memberExpression.Member.Name);
    

现在这样使用它：

.Including(BuildMemberExpression((Experimenter e) => e.Name))
.Including(BuildMemberExpression((Experimenter e) => e.Role))