TDD - Why does this Assert.AreSame pass? - c#

I have a test method...
[TestMethod]
public void MainViewModel_PropertiesReflectDataEntityProperties()
{
// Arrange
var facilityDataEntity = MockRepository.GenerateStub<FacilityDataEntity>();
var shopOrderDataEntity = MockRepository.GenerateStub<ShopOrderDataEntity>();
// Act
MainViewModel mainViewModel = new MainViewModel(facilityDataEntity, shopOrderDataEntity);
// Assert
Assert.AreSame(facilityDataEntity.Value, mainViewModel.FacilityValue);
}
... and the test passes. However, I have not implemented the mapping of the DataEntity's properties to the MainViewModel's properties yet! How can this be? I thought AreSame checks whether two references point to the same instance.
public class MainViewModel
{
private readonly FacilityDataEntity facilityDataEntity;
private readonly ShopOrderDataEntity shopOrderDataEntity;
public MainViewModel(FacilityDataEntity facilityDataEntity)
{
this.facilityDataEntity = facilityDataEntity;
}
public MainViewModel(FacilityDataEntity facilityDataEntity, ShopOrderDataEntity shopOrderDataEntity)
{
this.facilityDataEntity = facilityDataEntity;
this.shopOrderDataEntity = shopOrderDataEntity;
}
public ShopOrderDataEntity ShopOrderDataEntity
{
get { return shopOrderDataEntity; }
}
public FacilityDataEntity FacilityDataEntity
{
get { return facilityDataEntity; }
}
public int ShopOrder { get; set; }
public decimal RequiredQuantity { get; set; }
public string ItemCode { get; set; }
public string ItemDescription { get; set; }
public string FacilityValue { get; set; }
public string FacilityLabel { get; set; }
public static IEnumerable<MainViewModel> TranslateDataEntityList(IEnumerable<FacilityDataEntity> facilityDataEntityList)
{
foreach (FacilityDataEntity facilityDataEntity in facilityDataEntityList)
{
yield return new MainViewModel(facilityDataEntity);
}
}
public static IEnumerable<MainViewModel> TranslateDataEntityList(FacilityDataEntity facilityDataEntity, IEnumerable<ShopOrderDataEntity> shopOrderDataEntityList)
{
foreach (ShopOrderDataEntity shopOrderDataEntity in shopOrderDataEntityList)
{
yield return new MainViewModel(facilityDataEntity, shopOrderDataEntity);
}
}
}

Underneath it all, these tests are just using Object.ReferenceEquals:
true if objA is the same instance as objB or if both are null; otherwise, false.

I guess this is happening because they are both null.

in this case, I'd say its comparing null with null, which are the same.

Related

Check if an object exist in expected list

I have this class POCO
public class BankTransaction
{
public int Id { get; set; }
public decimal TransactionAmount { get; set; }
public TransactionTypeEnum TransactionType { get; set; }
public int BankAccountId { get; set; }
public BankTransaction(decimal TransactionAmount)
{
this.TransactionAmount = TransactionAmount;
}
}
public enum TransactionTypeEnum
{
Deposit, Withdraw, ThirdPartyTransfer
}
and this repository class insert the transaction
public class BankTransactionRepository : IBankTransactionRepository
{
// Mock DB
public List<BankTransaction> bankTransactions { get; private set; }
public BankTransactionRepository()
{
bankTransactions = new List<BankTransaction>();
}
public void InsertTransaction(BankTransaction bankTransaction)
{
bankTransactions.Add(bankTransaction);
}
}
and here is my xUnit unit test for InsertTransaction method which works except for expected.Should().Contain(trans); which support to check if trans object exists in expected list.
public class BankTransactionsTest
{
private BankTransactionRepository _bankTransaction;
public BankTransactionsTest()
{
_bankTransaction = new BankTransactionRepository();
}
// Arrange
[Theory, MemberData(nameof(InsertTransaction_InsertShouldPass_Data))]
public void InsertTransaction_InsertShouldPass(BankTransaction trans, List<BankTransaction> expected)
{
// Act
_bankTransaction.InsertTransaction(trans);
// Assert
Assert.Equal(expected.Count, _bankTransaction.bankTransactions.Count);
// Fluent Assertions to check if trans is in 'expected' list.
expected.Should().Contain(trans);
}
public static TheoryData<BankTransaction, List<BankTransaction>> InsertTransaction_InsertShouldPass_Data()
{
return new TheoryData<BankTransaction, List<BankTransaction>>
{
{
new BankTransaction(200.00M),
new List<BankTransaction>(){new BankTransaction(200.00M)}
},
{
new BankTransaction(50.50M),
new List<BankTransaction>(){new BankTransaction(50.50M)}
},
};
}
}
Change the approach to be more explicit about asserting the expected behavior:
That the object inserted when InsertTransaction is invoked, is actually contained in the subject under test.
public class BankTransactionsTest
{
private BankTransactionRepository _bankTransaction;
public BankTransactionsTest()
{
_bankTransaction = new BankTransactionRepository();
}
// Arrange
[Theory, MemberData(nameof(InsertTransaction_InsertShouldPass_Data))]
public void InsertTransaction_InsertShouldPass(BankTransaction transaction)
{
// Act
_bankTransaction.InsertTransaction(transaction);
// Assert
_bankTransaction.bankTransactions.Should().ContainEquivalentOf(transaction);
}
public static TheoryData<BankTransaction> InsertTransaction_InsertShouldPass_Data()
{
return new TheoryData<BankTransaction>
{
new BankTransaction(200.00M),
new BankTransaction(50.50M)
};
}
}

c# how to mock code line with several properties

I have this code:
Class VM
{
var MyVm;
public VM(ExternalEntities externalEntities){
MyVm = externalEntities.Reflcation.VM;
}
public bool IsVmPowerOn(){
//Do something
}
}
[TestMethod]
public void TestVM()
{
private Mock<IExternalEntities> m_externalEntities = new Mock<IExternalEntities>();
private Mock<IReflection> m_reflection = new Mock<IReflection>();
private Mock<IVm> m_vm= new Mock<IVm>();
m_externalEntities.Setup(x => x.Reflaction).Return(m_reflection.object);
m_reflection.Setup(x => x.VM).Return(m_vm.Object);
var testee = new VM(externalEntity.Object)
var ans = testee.IsVmPowerOn();
Assert.IsTrue(ans);
}
The problem is that externalEntities.Reflcation is null and the test throws a NullReferenceException so it can't activate the Vm property.
The test can't pass constructor.
The following code also throws a NullReferenceException:
m_externalEntities.Setup(x => x.Reflaction.VM).Return(m_vm.object);
How do you test this kind of code?
Why do I receive null after the setup and not the mock object?
You had a lot of compilation errors and missing pieces in your code. It was not compiling as-is. That being said, I fixed it up for you. Not sure what your trying to accomplish but this works.
public interface IVm
{
IVm MyVm { get; set; }
}
public class VM : IVm
{
public IVm MyVm { get; set; }
public VM(IExternalEntities externalEntities)
{
MyVm = externalEntities.Reflaction.VM;
}
public bool IsVmPowerOn()
{
//Do something
return true;
}
}
public interface IExternalEntities
{
IReflection Reflaction { get; set; }
}
public class ExternalEntities : IExternalEntities
{
public IReflection Reflaction { get; set; }
public ExternalEntities()
{
Reflaction = new Reflection();
}
}
public interface IReflection
{
IVm VM { get; set; }
}
public class Reflection : IReflection
{
public IVm VM { get; set; }
public Reflection()
{
VM = new VM(null);
}
}
Then using that, your test would look like this.
[TestMethod]
public void TestVM()
{
Mock<IExternalEntities> m_externalEntities = new Mock<IExternalEntities>();
Mock<IReflection> m_reflection = new Mock<IReflection>();
Mock<IVm> m_vm = new Mock<IVm>();
m_externalEntities.Setup(x => x.Reflaction).Returns(m_reflection.Object);
m_reflection.Setup(x => x.VM).Returns(m_vm.Object);
var testee = new VM(m_externalEntities.Object);
var ans = testee.IsVmPowerOn();
Assert.IsTrue(ans);
}

Type Casting Exception With Inheritance

Here is my code below. It gives me Casting exception problem at selIngs.Add(da). tried with the 2nd way. it still give me the same exception. I wonder where I am doing wrong? Once I implement the interface or inherit the base class it should be ok to treat child class as the same. Any idea please?
//1st way
public interface IngredientInterface
{
double Concentration { get; set; }
string DateCreated { get; set; }
string DevCode { get; set; }
}
public class IngredientData : INotifyPropertyChanged, IngredientInterface
{
public string GroupCode
{
get { return groupCode; }
set
{
groupCode = value;
}
}
public double Setpoint { get; set; }
public bool IsHighlighted { get; set; }
public double PPT { get; set; }
}
public class FormulaUploadViewModelData: IngredientData
{
//.....
}
public class FormulaUploadViewModel :INotifyPropertyChanged
{
public FormulaUploadViewModel()
{
selIngs = new List<FormulaUploadViewModelData>();
}
private void IngsUp()
{
List<IngredientData> someIngData = new List<IngredientData>();
foreach (FormulaUploadViewModelData da in someIngData)
{
selIngs.Add(da); //here gives me casting exception
}
}
}
//2nd way
public class FormulaUploadViewModelData: IngredientInterface
{
//.....
}
public class FormulaUploadViewModel :INotifyPropertyChanged
{
public FormulaUploadViewModel()
{
selIngs = new List<FormulaUploadViewModelData>();
}
private void IngsUp()
{
List<IngredientInterface> someIngData = new List<IngredientInterface>();
foreach (FormulaUploadViewModelData da in someIngData)
{
selIngs.Add(da); //here gives me casting exception
}
}
}
All FormulaUploadViewModelData are IngredientInterface. So this will work:
var ingredients = new List<IngredientInterface>();
ingredients.Add(new FormulaUploadViewModelData());
But the opposite does not work because not all IngredientInterface are FormulaUploadViewModelData which is what should follow from allowing:
var formulas = new
List<FormulaUploadViewModelData>();
formulas(someIngredientInterface);
Solution? Make sure the da you are adding is in fact a FormulaUploadViewModelData. There is quite a few ways to do it, to name a couple:
Pattern matching
foreach (var da in someInData)
if (da is FormulaUploadViewModelData formula)
selIngs.Add(formula)
Use Enumerable.OfType<> extension method
foreach (var formula in
someInData.OfType<FormulaUploadViewModelData>())
selIngs.Add(formula)
Etc.

C# Accessing custom attribute of owner object

How can I access the custom attribute of the parent or owner object.
Look at the FieldInfo property of the SQLFieldInfo struct
Here's a more detailed program that will compile and run that shows what I need.
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
Employee myclass = new Employee();
// Load from sql server...
myclass.Name = "Alain";
myclass.Age = 51;
//----
MessageBox.Show(myclass.Name.ToString()); // Should return Alain
MessageBox.Show(myclass.Age.FieldInfo.Type.ToString()); // Should output "int"
}
}
// This next class is generated by a helper exe that reads SQL table design and create the class from it
[SQLTableAttribute(DatabaseName = "Employees", Schema = "dbo", TableName = "Employees")]
public class Employee
{
[SQLFieldAttribute(FieldName = "ID", Type = SqlDbType.Int)]
public SQLFieldInfo<int> ID { get; set; }
[SQLFieldAttribute(FieldName = "Name", Type = SqlDbType.NVarChar, Size = 200)]
public SQLFieldInfo<String> Name { get; set; }
[SQLFieldAttribute(FieldName = "Age", Type = SqlDbType.Int)]
public SQLFieldInfo<int> Age { get; set; }
}
public struct SQLFieldInfo<T>
{
private readonly T value;
public SQLFieldInfo(T Value)
{
this.value = Value;
}
public static implicit operator SQLFieldInfo<T>(T Value)
{
return new SQLFieldInfo<T>(Value);
}
public T Value
{
get
{
return this.value;
}
}
public override string ToString()
{
return this.value.ToString();
}
public SQLFieldAttribute FieldInfo
{
get
{
// Need to retreive the attribute class of the parent or declaring member
return null;
}
}
}
// Holds the sql field information
public class SQLFieldAttribute : Attribute
{
public string FieldName { get; set; }
public SqlDbType Type { get; set; }
public bool AllowNull { get; set; }
public int Size { get; set; }
}
// Holds the sql table information
public class SQLTableAttribute : Attribute
{
public string DatabaseName { get; set; }
public string Schema { get; set; } = "dbo";
public string TableName { get; set; }
}
Thank you!
Alain
My data class is as follows (should be fairly translatable to A above):
public class Foo
{
[Argument(Help = "Name", AssignmentDelimiter = "=")]
public string Name
{
get;
set;
}
}
A helper class is responsible of reading attribute values of objects:
static public string GetCommandLineDelimiter<T>(Expression<Func<T>> property)
{
if(property != null)
{
var memberExpression = (MemberExpression)property.Body;
string propertyName = memberExpression.Member.Name;
PropertyInfo prop = typeof(Arguments).GetProperty(propertyName);
if(prop != null)
{
object[] dbFieldAtts = prop.GetCustomAttributes(typeof(ArgumentAttribute), true);
if(dbFieldAtts.Length > 0)
{
return ((ArgumentAttribute)dbFieldAtts[0]).AssignmentDelimiter;
}
}
}
return null;
}
To use it, simply:
string delimiter = GetCommandLineDelimiter(() => myObject.Name);
That will get the attribute value of AssignmentDelimiter on property Name, i.e. "=".
First, MSDN is your friend.
Then, if you want to get the attributes for ancestors just specify true in the inherit flag of the method:
var attribute = typeof(A).GetProperty("myprop").GetCustomAttributes(true)
.OfType<MycustomAttrib>().FirstOrDefault();
This works. I am doing a lazy initialization of a reference to the custom attribute by using reflection to look at all the properties of all the types.
public class MycustomAttribAttribute : Attribute
{
public MycustomAttribAttribute(string name)
{
this.Name=name;
}
public string Name { get; private set; }
}
class A
{
public A() { MyProp=new B(); }
[MycustomAttrib(name: "OK")]
public B MyProp { get; set; }
}
class B
{
private static Lazy<MycustomAttribAttribute> att = new Lazy<MycustomAttribAttribute>(() =>
{
var types = System.Reflection.Assembly.GetExecutingAssembly().DefinedTypes;
foreach(var item in types)
{
foreach(var prop in item.DeclaredProperties)
{
var attr = prop.GetCustomAttributes(typeof(MycustomAttribAttribute), false);
if(attr.Length>0)
{
return attr[0] as MycustomAttribAttribute;
}
}
}
return null;
});
public string MyProp2
{
get
{
return att.Value.Name;
}
}
}
class Program
{
static void Main(string[] args)
{
// Finds the attribute reference and returns "OK"
string name = (new A()).MyProp.MyProp2;
// Uses the stored attribute reference to return "OK"
string name2 = (new A()).MyProp.MyProp2;
}
}

Stack overflow error in singleton pattern

I have implemented Single Pattern. Here is my code i am getting the an error when i call the Test.BuildData() function. Please help
public class WordDataItem
{
public string Word { get; set; }
public string Definition { get; set; }
public int WordGroupKey { get; set; }
}
public class WordDataGroup
{
public List<WordDataItem> listItem = new List<WordDataItem>();
public int GroupKey { get; set; }
}
public sealed class WordDataSource
{
private static WordDataSource _dataSoruce;
private List<WordDataGroup> listGroup = new List<WordDataGroup>();
public List<WordDataGroup> ListGroup
{
get { return listGroup; }
set { listGroup = value; }
}
private WordDataSource() { }
public static WordDataSource Instance
{
get
{
if (Instance == null)
{
_dataSoruce = new WordDataSource();
}
return _dataSoruce;
}
}
}
public static class Test
{
public static void BuildData()
{
WordDataSource.Instance.ListGroup.Add(new WordDataGroup() { GroupKey = 8, listItem = new List<WordDataItem>() { new WordDataItem() {Word = "Hello", Definition="Greetings", WordGroupKey = 8}} });
}
}
I get an error of stack over flow when i call the Test.BuildData() function.
Your Instance property is recursively calling into itself when you check if it is null.
Try this:
public static WordDataSource Instance
{
get
{
if (_dataSoruce == null)
{
_dataSoruce = new WordDataSource();
}
return _dataSoruce;
}
}

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