Mocking issue: Can not instantiate proxy of class. Could not find a parameterless constructor

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I am trying to write unit test for a class which I can not change implementation.
Below is the error which I am seeing while writing tests.

Unit to Mock:

public class ClassA : IInterface

{

    public readonly ClassB _classB = null;



    public ClassA(ClassB classB)

    {

        _classB = classB;

    }



    private ClassP<ClassB, ClassC> _classP;



    public virtual ClassP<ClassB, ClassC> TargetToMock => _classP ?? (_classP = new ClassP<ClassB, ClassC>(_classB));

}

Mocking:

MockClassB = new Mock<ClassB>();



MockClassA = new Mock<ClassA>(MockClassB.Object);

Setup:

MockClassA

    .Setup(s => s.TargetToMock.SomeMethod(argument1, argument2))

    .Returns(SomeResponseObject);

Exception:

Castle.DynamicProxy.InvalidProxyConstructorArgumentsException : Can
not instantiate proxy of class: ClassP`2[[ClassB, Version=1.0.0.0,
Culture=neutral, PublicKeyToken=null],[ClassC, Version=1.0.0.0,
Culture=neutral, PublicKeyToken=null]].
Could not find a parameterless constructor.

edited Nov 5 at 2:20

asked Nov 5 at 1:57

sillydeveloper

New contributor

I think the correct way is MockClassA = new ClassA(MockClassB.Object)
– Kien Chu
Nov 5 at 2:00

you are right, actually I have a typo in the question
– sillydeveloper
Nov 5 at 2:18

add a comment |

up vote
0
down vote

favorite

I am trying to write unit test for a class which I can not change implementation.
Below is the error which I am seeing while writing tests.

Unit to Mock:

public class ClassA : IInterface

{

    public readonly ClassB _classB = null;



    public ClassA(ClassB classB)

    {

        _classB = classB;

    }



    private ClassP<ClassB, ClassC> _classP;



    public virtual ClassP<ClassB, ClassC> TargetToMock => _classP ?? (_classP = new ClassP<ClassB, ClassC>(_classB));

}

Mocking:

MockClassB = new Mock<ClassB>();



MockClassA = new Mock<ClassA>(MockClassB.Object);

Setup:

MockClassA

    .Setup(s => s.TargetToMock.SomeMethod(argument1, argument2))

    .Returns(SomeResponseObject);

Exception:

Castle.DynamicProxy.InvalidProxyConstructorArgumentsException : Can
not instantiate proxy of class: ClassP`2[[ClassB, Version=1.0.0.0,
Culture=neutral, PublicKeyToken=null],[ClassC, Version=1.0.0.0,
Culture=neutral, PublicKeyToken=null]].
Could not find a parameterless constructor.

edited Nov 5 at 2:20

asked Nov 5 at 1:57

sillydeveloper

New contributor

I think the correct way is MockClassA = new ClassA(MockClassB.Object)
– Kien Chu
Nov 5 at 2:00

you are right, actually I have a typo in the question
– sillydeveloper
Nov 5 at 2:18

add a comment |

up vote
0
down vote

favorite

I am trying to write unit test for a class which I can not change implementation.
Below is the error which I am seeing while writing tests.

Unit to Mock:

public class ClassA : IInterface

{

    public readonly ClassB _classB = null;



    public ClassA(ClassB classB)

    {

        _classB = classB;

    }



    private ClassP<ClassB, ClassC> _classP;



    public virtual ClassP<ClassB, ClassC> TargetToMock => _classP ?? (_classP = new ClassP<ClassB, ClassC>(_classB));

}

Mocking:

MockClassB = new Mock<ClassB>();



MockClassA = new Mock<ClassA>(MockClassB.Object);

Setup:

MockClassA

    .Setup(s => s.TargetToMock.SomeMethod(argument1, argument2))

    .Returns(SomeResponseObject);

Exception:

Castle.DynamicProxy.InvalidProxyConstructorArgumentsException : Can
not instantiate proxy of class: ClassP`2[[ClassB, Version=1.0.0.0,
Culture=neutral, PublicKeyToken=null],[ClassC, Version=1.0.0.0,
Culture=neutral, PublicKeyToken=null]].
Could not find a parameterless constructor.

edited Nov 5 at 2:20

asked Nov 5 at 1:57

sillydeveloper

New contributor

I am trying to write unit test for a class which I can not change implementation.
Below is the error which I am seeing while writing tests.

Unit to Mock:

public class ClassA : IInterface

{

    public readonly ClassB _classB = null;



    public ClassA(ClassB classB)

    {

        _classB = classB;

    }



    private ClassP<ClassB, ClassC> _classP;



    public virtual ClassP<ClassB, ClassC> TargetToMock => _classP ?? (_classP = new ClassP<ClassB, ClassC>(_classB));

}

Mocking:

MockClassB = new Mock<ClassB>();



MockClassA = new Mock<ClassA>(MockClassB.Object);

Setup:

MockClassA

    .Setup(s => s.TargetToMock.SomeMethod(argument1, argument2))

    .Returns(SomeResponseObject);

Exception:

Castle.DynamicProxy.InvalidProxyConstructorArgumentsException : Can
not instantiate proxy of class: ClassP`2[[ClassB, Version=1.0.0.0,
Culture=neutral, PublicKeyToken=null],[ClassC, Version=1.0.0.0,
Culture=neutral, PublicKeyToken=null]].
Could not find a parameterless constructor.

c# .net unit-testing mocking moq

edited Nov 5 at 2:20

asked Nov 5 at 1:57

sillydeveloper

New contributor

edited Nov 5 at 2:20

asked Nov 5 at 1:57

sillydeveloper

New contributor

edited Nov 5 at 2:20

asked Nov 5 at 1:57

sillydeveloper

New contributor

asked Nov 5 at 1:57

sillydeveloper

asked Nov 5 at 1:57

sillydeveloper

New contributor

sillydeveloper is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

I think the correct way is MockClassA = new ClassA(MockClassB.Object)
– Kien Chu
Nov 5 at 2:00

you are right, actually I have a typo in the question
– sillydeveloper
Nov 5 at 2:18

add a comment |

I think the correct way is MockClassA = new ClassA(MockClassB.Object)
– Kien Chu
Nov 5 at 2:00

you are right, actually I have a typo in the question
– sillydeveloper
Nov 5 at 2:18

I think the correct way is MockClassA = new ClassA(MockClassB.Object)
– Kien Chu
Nov 5 at 2:00

you are right, actually I have a typo in the question
– sillydeveloper
Nov 5 at 2:18

add a comment |

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