我不确定如何将EF融入我的业务逻辑测试中。让我举一个例子说明它在运行时是如何工作的（没有测试，常规应用程序运行）：
Context.Set<T>.Add(instance);
当我使用上面的泛型方法添加实体时，会将一个实例添加到上下文中，EF会修复幕后的所有导航属性。例如，如果存在[instance.Parent]属性和[parent.Instances]集合属性（1对多关系），EF将自动将实例添加到幕后的parent.Instances集合中。
我的代码取决于[parent.Instances]集合，如果它是空的，它将失败。当我使用MS测试框架编写单元测试时，如何重用EF的功能，所以它仍然可以完成幕后工作，但是将内存作为数据存储而不是实际的数据库？我对EF是否成功添加，修改或删除了数据库中的某些内容并不感兴趣，我只是想在内存集中获得EF魔法。
答案 0 :(得分：3)
我一直在使用我创建的模拟DbContext和模拟DbSet。它们将测试数据存储在内存中，并允许您执行可在DbSet上执行的大多数标准操作。
最初获取DbContext的代码必须进行更改，以便在单元测试下运行时获取MockDbContext。您可以使用以下代码确定您是否在MSTest下运行：
{ field_a: abc,
field_b: def,
sub_docs:
[ { score: 1 },
{ score: 1 },
{ score: 1 } ] }
以下是MockDbContext的代码：
public static bool IsInUnitTest
{
get
{
return AppDomain.CurrentDomain.GetAssemblies()
.Any(assembly =>
assembly.FullName.StartsWith(
"Microsoft.VisualStudio.QualityTools.UnitTestFramework"));
}
}
这是MockDbSet的代码：
using System;
using System.Collections.Generic;
using System.Data.Common;
using System.Data.Entity;
using System.Data.Entity.Core.Objects;
using System.Data.Entity.Infrastructure;
using System.Threading;
using System.Threading.Tasks;
namespace ConsoleApplication5
{
// ProductionDbContext would be DbContext class
// generated by Entity Framework
public class MockDbContext: ProductionDbContext
{
public MockDbContext()
{
LoadFakeData();
}
// Entities (for which we'll provide MockDbSet implementation
// and test data)
public override DbSet<Account> Accounts { get; set; }
public override DbSet<AccountGenLink> AccountGenLinks { get; set; }
public override DbSet<AccountPermit> AccountPermits { get; set; }
public override DbSet<AcctDocGenLink> AcctDocGenLinks { get; set; }
// DbContext method overrides
private int InternalSaveChanges()
{
// Just return 0 in the mock
return 0;
}
public override int SaveChanges()
{
return InternalSaveChanges();
}
public override Task<int> SaveChangesAsync()
{
return Task.FromResult(InternalSaveChanges());
}
public override Task<int> SaveChangesAsync(CancellationToken cancellationToken)
{
// Just ignore the cancellation token in the mock
return SaveChangesAsync();
}
private void LoadFakeData()
{
// Tables
Accounts = new MockDbSet<Account>(this);
Accounts.AddRange(new List<Account>
{
new Account
{
SSN_EIN = "123456789", CODE = "A", accttype = "CD",
acctnumber = "1", pending = false, BankOfficer1 = string.Empty,
BankOfficer2 = null, Branch = 0, type = "18", drm_rate_code = "18",
officer_code = string.Empty, open_date = new DateTime(2010, 6, 8),
maturity_date = new DateTime(2010, 11, 8), HostAcctActive = true,
EffectiveAcctStatus = "A"
},
new Account
{
SSN_EIN = "123456789", CODE = "A", accttype = "DD",
acctnumber = "00001234", pending = false, BankOfficer1 = "BCK",
BankOfficer2 = string.Empty, Branch = 0, type = "05", drm_rate_code = "00",
officer_code = "DJT", open_date = new DateTime(1998, 9, 14),
maturity_date = null, HostAcctActive = true,
EffectiveAcctStatus = "A"
},
new Account
{
SSN_EIN = "123456789", CODE = "A", accttype = "LN", acctnumber = "1",
pending = false, BankOfficer1 = "LMP", BankOfficer2 = string.Empty,
Branch = 0, type = "7", drm_rate_code = null, officer_code = string.Empty,
open_date = new DateTime(2001, 10, 24),
maturity_date = new DateTime(2008, 5, 2), HostAcctActive = true,
EffectiveAcctStatus = "A"
}
});
AccountGenLinks = new MockDbSet<AccountGenLink>(this);
AccountGenLinks.AddRange(new List<AccountGenLink>
{
// Add your test data here if needed
});
AccountPermits = new MockDbSet<AccountPermit>(this);
AccountPermits.AddRange(new List<AccountPermit>
{
// Add your test data here if needed
});
AcctDocLinks = new MockDbSet<AcctDocLink>(this);
AcctDocLinks.AddRange(new List<AcctDocLink>
{
new AcctDocLink { ID = 1, SSN_EIN = "123456789", CODE = "A", accttype = "DD",
acctnumber = "00001234", DocID = 50, DocType = 5 },
new AcctDocLink { ID = 25, SSN_EIN = "123456789", CODE = "6", accttype = "CD",
acctnumber = "1", DocID = 6750, DocType = 5 }
});
}
}
}
答案 1 :(得分：0)
如果您使用EntityFramework-Reverse-POCO-Code-First-Generator from Simon Hughes及其生成的FakeContext，则通过一些调整仍然可以使用Jeff Prince的方法。此处的微小区别是我们使用了部分类支持，并在FakeContext和FakeDbSet中实现了InitializePartial（）方法。更大的区别在于，反向POCO FakeContext不能从DbContext继承，因此我们无法轻松地使MetadataWorkspace知道哪些列是标识。答案是使用虚假的连接字符串创建“真实”上下文，并使用该上下文获取FakeDbSet的EntitySetBase。应当将其粘贴到新源文件的适当名称空间中，重命名上下文，并且在项目的其余部分中无需执行任何其他操作。
/// <summary>
/// This code will set Identity columns to be unique. It behaves differently from the real context in that the
/// identities are generated on add, not save. This is inspired by https://stackoverflow.com/a/31795273/1185620 and
/// modified for use with the FakeDbSet and FakeContext that can be generated by EntityFramework-Reverse-POCO-Code-
/// First-Generator from Simon Hughes.
///
/// Aside from changing the name of the FakeContext and the type used to in its InitializePartial() as
/// the 'realContext' this file can be pasted into another namespace for a completely unrelated context. If you
/// have additional implementation for the InitializePartial methods in the FakeContext or FakeDbSet, change the
/// name to InitializePartial2 and they will be called after InitializePartial is called here. Please don't add
/// code unrelated to the above purpose to this file - make another file to further extend the partial class.
/// </summary>
partial class FakeFooBarBazContext
{
/// <summary> Initialization of FakeContext to handle setting an identity for columns marked as
/// <c>IsStoreGeneratedIdentity</c> when an item is Added to the DbSet. If this signature
/// conflicts with another partial class, change that signature to implement
/// <see cref="InitializePartial2"/>, as that will be called when this is complete. </summary>
partial void InitializePartial()
{
// Here we need to get a 'real' ObjectContext so we can get the metadata for determining
// identity columns. Since FakeContext doesn't inherit from DbContext, create
// the real one with a bogus connection string.
using (var realContext = new FooBarBazContext("Server=."))
{
var objectContext = (realContext as IObjectContextAdapter).ObjectContext;
// Reflect over the public properties that return DbSet<> and get it. If it is
// of type FakeDbSet<>, call InitializeWithContext() on it.
var fakeDbSetGenericType = typeof(FakeDbSet<>);
var dbSetGenericType = typeof(DbSet<>);
var properties = this.GetType().GetProperties(BindingFlags.Public | BindingFlags.Instance);
foreach (var prop in properties)
{
if (!prop.PropertyType.IsGenericType || prop.GetMethod == null)
continue;
if (prop.PropertyType.GetGenericTypeDefinition() != dbSetGenericType)
continue;
var dbSetObj = prop.GetMethod.Invoke(this, null);
var dbSetObjType = dbSetObj?.GetType();
if (dbSetObjType?.GetGenericTypeDefinition() != fakeDbSetGenericType)
continue;
var initMethod = dbSetObjType.GetMethod(nameof(FakeDbSet<object>.InitializeWithContext),
BindingFlags.NonPublic | BindingFlags.Instance,
null, new[] {typeof(ObjectContext)}, new ParameterModifier[] { });
initMethod.Invoke(dbSetObj, new object[] {objectContext});
}
}
InitializePartial2();
}
partial void InitializePartial2();
}
partial class FakeDbSet<TEntity>
{
private EntitySetBase EntitySet { get; set; }
/// <summary> Initialization of FakeDbSet to handle setting an identity for columns marked as
/// <c>IsStoreGeneratedIdentity</c> when an item is Added to the DbSet. If this signature
/// conflicts with another partial class, change that signature to implement
/// <see cref="InitializePartial2"/>, as that will be called when this is complete. </summary>
partial void InitializePartial()
{
// The only way we know something was added to the DbSet from this partial class
// is to hook the CollectionChanged event.
_data.CollectionChanged += DataOnCollectionChanged;
InitializePartial2();
}
internal void InitializeWithContext(ObjectContext objectContext)
{
// Get entity set for entity. Used when we figure out whether to generate IDENTITY values
EntitySet = objectContext
.MetadataWorkspace
.GetItems<EntityContainer>(DataSpace.SSpace).First()
.BaseEntitySets
.FirstOrDefault(item => item.Name == typeof(TEntity).Name);
}
private void DataOnCollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
{
if (e.Action != NotifyCollectionChangedAction.Add)
return;
foreach (TEntity entity in e.NewItems)
GenerateIdentityColumnValues(entity);
}
/// <summary> The purpose of this method, which is called after a row is added, is to ensure that Identity column values are
/// properly initialized. If this was a real Entity Framework, this task would be handled by the data provider
/// when SaveChanges[Async]() is called and the value(s) would then be propagated back into the entity.
/// In the case of FakeDbSet, there is nothing that will do that, so we have to make this at-least token effort
/// to ensure the columns are properly initialized, even if it is done at the incorrect time.
/// </summary>
private void GenerateIdentityColumnValues(TEntity entity)
{
foreach (var member in EntitySet.ElementType.Members)
{
if (!member.IsStoreGeneratedIdentity)
continue;
foreach (var metadataProperty in member.TypeUsage.EdmType.MetadataProperties)
{
if (metadataProperty.Name != "PrimitiveTypeKind")
continue;
var entityProperty = entity.GetType().GetProperty(member.Name);
var identityColumnGetter = entityProperty.GetGetMethod();
// Note that we'll get the current value of the column and,
// if it is nonzero, we'll leave it alone. We do this because
// the test data in our mock DbContext provides values for the
// Identity columns and many of those values are foreign keys
// in other entities (where we also provide test data). We don't
// want to disturb any existing relationships defined in the test data.
bool isDefaultForType;
var columnType = (PrimitiveTypeKind)metadataProperty.Value;
switch (columnType)
{
case PrimitiveTypeKind.SByte:
isDefaultForType = default(SByte) == (SByte)identityColumnGetter.Invoke(entity, null);
break;
case PrimitiveTypeKind.Int16:
isDefaultForType = default(Int16) == (Int16)identityColumnGetter.Invoke(entity, null);
break;
case PrimitiveTypeKind.Int32:
isDefaultForType = default(Int32) == (Int32)identityColumnGetter.Invoke(entity, null);
break;
case PrimitiveTypeKind.Int64:
isDefaultForType = default(Int64) == (Int64)identityColumnGetter.Invoke(entity, null);
break;
case PrimitiveTypeKind.Decimal:
isDefaultForType = default(Decimal) == (Decimal)identityColumnGetter.Invoke(entity, null);
break;
default:
// In SQL Server, an Identity column can be of one of the following data types:
// tinyint (SqlByte, byte), smallint (SqlInt16, Int16), int (SqlInt32, Int32),
// bigint (SqlInt64, Int64), decimal (with a scale of 0) (SqlDecimal, Decimal),
// or numeric (with a scale of 0) (SqlDecimal, Decimal). Those are handled above.
// 'If we don't know, we throw'
throw new InvalidOperationException($"Unsupported Identity Column Type {columnType}");
}
// From this point on, we can return from the method, as only one identity column is
// possible per table and we found it.
if (!isDefaultForType)
return;
var identityColumnSetter = entityProperty.GetSetMethod();
lock (Local)
{
switch (columnType)
{
case PrimitiveTypeKind.SByte:
{
SByte maxExistingColumnValue = 0;
foreach (var item in Local.ToList())
maxExistingColumnValue = Math.Max(maxExistingColumnValue, (SByte) identityColumnGetter.Invoke(item, null));
identityColumnSetter.Invoke(entity, new object[] {(SByte) (++maxExistingColumnValue)});
return;
}
case PrimitiveTypeKind.Int16:
{
Int16 maxExistingColumnValue = 0;
foreach (var item in Local.ToList())
maxExistingColumnValue = Math.Max(maxExistingColumnValue, (Int16) identityColumnGetter.Invoke(item, null));
identityColumnSetter.Invoke(entity, new object[] {(Int16) (++maxExistingColumnValue)});
return;
}
case PrimitiveTypeKind.Int32:
{
Int32 maxExistingColumnValue = 0;
foreach (var item in Local.ToList())
maxExistingColumnValue = Math.Max(maxExistingColumnValue, (Int32) identityColumnGetter.Invoke(item, null));
identityColumnSetter.Invoke(entity, new object[] {(Int32) (++maxExistingColumnValue)});
return;
}
case PrimitiveTypeKind.Int64:
{
Int64 maxExistingColumnValue = 0;
foreach (var item in Local.ToList())
maxExistingColumnValue = Math.Max(maxExistingColumnValue, (Int64) identityColumnGetter.Invoke(item, null));
identityColumnSetter.Invoke(entity, new object[] {(Int64) (++maxExistingColumnValue)});
return;
}
case PrimitiveTypeKind.Decimal:
{
Decimal maxExistingColumnValue = 0;
foreach (var item in Local.ToList())
maxExistingColumnValue = Math.Max(maxExistingColumnValue, (Decimal) identityColumnGetter.Invoke(item, null));
identityColumnSetter.Invoke(entity, new object[] {(Decimal) (++maxExistingColumnValue)});
return;
}
}
}
}
}
}
partial void InitializePartial2();
}