In this blog,
we will learn how to write the unit test that verify, the exception has been thrown
in case of invalid input or validation rules violation.
There are two
way, we can verify that calling method has been throw specified type exception:
·
Assert.ThrowException
method
·
ExpectedException
attribute
Here is a business
class, which perform the validation rule and create or update person record and
if validation rule is dishonored, it throw validation exception
What are the benefits of unit testing?
public class PersonEngine
{
IPersonReposirty _personReposirty;
public PersonEngine(IPersonReposirty personReposirty)
{
_personReposirty
= personReposirty;
}
public Person CreatePerson(Person person)
{
if(person.PersonName == null)
{
throw new ValidationException("Person Name Cannot be
blank");
}
if (!validSSN(person.SSN))
{
throw new ValidationException("SSN is
not valid");
}
return
_personReposirty.CreatePerson(person);
}
private bool validSSN(string ssn)
{
return Regex.IsMatch(ssn, @"^(?:\d{9}|\d{3}-\d{2}-\d{4})$");
}
}
The PersonEngine
Class performs the below validations before call to repository object to create
a new person record.
·
Person
Name should not be blank.
·
SSN
should be invalid format.
By Using Assert.ThrowsException
method:
Here are unit tests which use Assert.ThrowsException
method to verify that
if the business or validation are failed, it throw Validation Exception
1.
Verify
Person Name, Person Name is required
[TestMethod]
public void Verify_Person_Name_Blank()
{
PersonEngine personEngine;
Mock<IPersonReposirty> _mockRepository = new Mock<IPersonReposirty>();
Person person = new Person
{
PersonName =
null,
SSN = "123456789"
};
_mockRepository.Setup(x => x.CreatePerson(person)).Returns(person);
personEngine = new PersonEngine(_mockRepository.Object);
Assert.ThrowsException<ValidationException>(() => personEngine.CreatePerson(person));
}
2.
Verify
SSN Length, It should be 9 digit
[TestMethod]
public void Verify_SSN_InValid_Length()
{
PersonEngine personEngine;
Mock<IPersonReposirty> _mockRepository = new Mock<IPersonReposirty>();
Person person = new Person
{
PersonName =
new PersonName { FirstName = "Tom", LastName = "Dick" },
SSN = "12345678"
};
_mockRepository.Setup(x => x.CreatePerson(person)).Returns(person);
personEngine = new PersonEngine(_mockRepository.Object);
Assert.ThrowsException<ValidationException>(() => personEngine.CreatePerson(person));
}
3.
Verify
SSN Format , It should be {3}-{2}-{4}
[TestMethod]
public void Verify_SSN_InValid_Format()
{
PersonEngine personEngine;
Mock<IPersonReposirty> _mockRepository = new Mock<IPersonReposirty>();
Person person = new Person
{
PersonName =
new PersonName { FirstName = "Tom", LastName = "Dick" },
SSN = "1234-567-89"
};
_mockRepository.Setup(x => x.CreatePerson(person)).Returns(person);
personEngine = new PersonEngine(_mockRepository.Object);
Assert.ThrowsException<ValidationException>(() => personEngine.CreatePerson(person));
}
Here is unit
test result:
By Using ExpectedException
Attribute:
Here are unit tests which use ExpectedException Attribute to verify that if the business or validation are
failed, it throw Validation Exception
1.
Verify
Person Name, Person Name is required
[TestMethod]
[ExpectedException(typeof(ValidationException))]
public void Verify_Person_Name_Blank()
{
PersonEngine personEngine;
Mock<IPersonReposirty> _mockRepository = new Mock<IPersonReposirty>();
Person person = new Person
{
PersonName =
null,
SSN = "123456789"
};
_mockRepository.Setup(x => x.CreatePerson(person)).Returns(person);
personEngine = new PersonEngine(_mockRepository.Object);
personEngine.CreatePerson(person);
}
2.
Verify
SSN Length, It should be 9 digit
[TestMethod]
[ExpectedException(typeof(ValidationException))]
public void Verify_SSN_InValid_Length()
{
PersonEngine personEngine;
Mock<IPersonReposirty> _mockRepository = new Mock<IPersonReposirty>();
Person person = new Person
{
PersonName =
new PersonName { FirstName = "Tom", LastName = "Dick" },
SSN = "12345678"
};
_mockRepository.Setup(x => x.CreatePerson(person)).Returns(person);
personEngine = new PersonEngine(_mockRepository.Object);
personEngine.CreatePerson(person);
}
3.
Verify
SSN Format , It should be {3}-{2}-{4}
[TestMethod]
[ExpectedException(typeof(ValidationException))]
public void Verify_SSN_InValid_Format()
{
PersonEngine personEngine;
Mock<IPersonReposirty> _mockRepository = new Mock<IPersonReposirty>();
Person person = new Person
{
PersonName =
new PersonName { FirstName = "Tom", LastName = "Dick" },
SSN = "1234-567-89"
};
_mockRepository.Setup(x => x.CreatePerson(person)).Returns(person);
personEngine = new PersonEngine(_mockRepository.Object);
personEngine.CreatePerson(person);
}
