下面的示例代码在生产中工作正常,但不能单位 测试因为EntityFunctions。
我的单元测试项目正在使用 InMemoryDatabase而不是真正的SQL数据库。我可以轻松解决我的问题 通过使用计算列在SQL数据库中创建视图的问题 myValue和newValue。我想找一种方法来进行单元测试工作 无需更改我的方法,也无需创建新的SQL视图
public class EcaseReferralCaseRepository : Repository
{
public class myType
{
public DateTime myValue;
public DateTime newValue;
}
public myType GetNewValues()
{
return
(myType)(from o in context.EcaseReferralCases
select new myType
{
// LINQ to Entity
myValue = (DateTime)System.Data.Objects.EntityFunctions.AddDays(o.StartDate, 0),
newValue = (DateTime)System.Data.Objects.EntityFunctions.AddDays(o.StartDate, 30)
// LINQ to Object
//myValue = o.StartDate.AddDays(0),
//newValue = o.StartDate.AddDays(30)
});
}
}
This link shows a good example to unit test EntityFunctions,我用这种方法来解决我的一个单元测试难度,但不知道如何解决这个问题。
答案 0 :(得分:5)
除非我弄错了,否则您将使用另一个IQueryable
切换EcaseReferralCases的实现,可能是LINQ To Objects可查询源。
最强大的方法可能是使用表达式访问者将EntityFunctions
的调用替换为您自己的L2Objects兼容函数。
这是我的实施:
using System;
using System.Data.Objects;
using System.Linq;
using System.Linq.Expressions;
static class EntityFunctionsFake
{
public static DateTime? AddDays(DateTime? original, int? numberOfDays)
{
if (!original.HasValue || !numberOfDays.HasValue)
{
return null;
}
return original.Value.AddDays(numberOfDays.Value);
}
}
public class EntityFunctionsFakerVisitor : ExpressionVisitor
{
protected override Expression VisitMethodCall(MethodCallExpression node)
{
if (node.Method.DeclaringType == typeof(EntityFunctions))
{
var visitedArguments = Visit(node.Arguments).ToArray();
return Expression.Call(typeof(EntityFunctionsFake), node.Method.Name, node.Method.GetGenericArguments(), visitedArguments);
}
return base.VisitMethodCall(node);
}
}
class VisitedQueryProvider<TVisitor> : IQueryProvider
where TVisitor : ExpressionVisitor, new()
{
private readonly IQueryProvider _underlyingQueryProvider;
public VisitedQueryProvider(IQueryProvider underlyingQueryProvider)
{
if (underlyingQueryProvider == null) throw new ArgumentNullException();
_underlyingQueryProvider = underlyingQueryProvider;
}
private static Expression Visit(Expression expression)
{
return new TVisitor().Visit(expression);
}
public IQueryable<TElement> CreateQuery<TElement>(Expression expression)
{
return new VisitedQueryable<TElement, TVisitor>(_underlyingQueryProvider.CreateQuery<TElement>(Visit(expression)));
}
public IQueryable CreateQuery(Expression expression)
{
var sourceQueryable = _underlyingQueryProvider.CreateQuery(Visit(expression));
var visitedQueryableType = typeof(VisitedQueryable<,>).MakeGenericType(
sourceQueryable.ElementType,
typeof(TVisitor)
);
return (IQueryable)Activator.CreateInstance(visitedQueryableType, sourceQueryable);
}
public TResult Execute<TResult>(Expression expression)
{
return _underlyingQueryProvider.Execute<TResult>(Visit(expression));
}
public object Execute(Expression expression)
{
return _underlyingQueryProvider.Execute(Visit(expression));
}
}
public class VisitedQueryable<T, TExpressionVisitor> : IOrderedQueryable<T>
where TExpressionVisitor : ExpressionVisitor, new()
{
private readonly IQueryable<T> _underlyingQuery;
private readonly VisitedQueryProvider<TExpressionVisitor> _queryProviderWrapper;
public VisitedQueryable(IQueryable<T> underlyingQuery)
{
_underlyingQuery = underlyingQuery;
_queryProviderWrapper = new VisitedQueryProvider<TExpressionVisitor>(underlyingQuery.Provider);
}
public IEnumerator<T> GetEnumerator()
{
return _underlyingQuery.GetEnumerator();
}
IEnumerator IEnumerable.GetEnumerator()
{
return GetEnumerator();
}
public Expression Expression
{
get { return _underlyingQuery.Expression; }
}
public Type ElementType
{
get { return _underlyingQuery.ElementType; }
}
public IQueryProvider Provider
{
get { return _queryProviderWrapper; }
}
}
这是一个使用示例:
var linq2ObjectsSource = new List<DateTime?>() { null }.AsQueryable();
var visitedSource = new VisitedQueryable<DateTime?, EntityFunctionsFakerVisitor>(linq2ObjectsSource);
var visitedQuery = visitedSource.Select(dt => EntityFunctions.AddDays(dt, 1));
var results = visitedQuery.ToList();
Assert.AreEqual(1, results.Count);
Assert.AreEqual(null, results[0]);
通过这种方式,您可以获得所有理想的特征:
EntityFunctions
; 答案 1 :(得分:1)
而不是打电话
System.Data.Objects.EntityFunctions.AddDays
直接,我会注入一个自定义接口,该接口将调用转发给该方法,但可以进行模拟以进行测试。
答案 2 :(得分:0)
我喜欢像Jean Hominal推荐的那样实现ExpressionVisitor。我的困难是如何在我的情况下定义linq2ObjectsSource,visitedSource和visitedQuery。最后,我只是为方法IQuerable GetSelectQuery(IQuerable查询)创建一个接口,然后在Production和Test项目中有相应的类,该类派生自该接口并具有GetSelectQuery(IQuerable查询)的实现。它工作正常。
public interface IEntityFunctionsExpressions
{
IQuerable<myType> GetSelectQuery(IQuerable<EcaseReferralCase> query);
}
在生产项目中:
public class EntityFunctionsExpressions : IEntityFunctionsExpressions
{
public EntityFunctionsExpressions()
{
}
public IQuerable<myType> GetSelectQuery(IQuerable<EcaseReferralCase> query)
{
// Expression for LINQ to Entities, does not work with LINQ to Objects
return
(myType)(from o in query
select new myType
{
// LINQ to Entity
myValue = (DateTime)System.Data.Objects.EntityFunctions.AddDays(o.StartDate, 0),
newValue = (DateTime)System.Data.Objects.EntityFunctions.AddDays(o.StartDate, 30)
});
}
}
单元测试项目中的:
public class MockEntityFunctionsExpressions : IEntityFunctionsExpressions
{
public MockEntityFunctionsExpressions()
{
}
public IQuerable<myType> GetSelectQuery(IQuerable<EcaseReferralCase> query)
{
// Expression for LINQ to Objects, does not work with LINQ to Entities
return
(myType)(from o in query
select new myType
{
// LINQ to Object
myValue = o.StartDate.AddDays(0),
newValue = o.StartDate.AddDays(30)
});
}
}
然后重写GetNewValues()方法:
public myType GetNewValues() { return myrepository.EntityFunctionsExpressions.GetSelectQuery(context.EcaseReferralCases);
}