NullReferenceException in unittesting with NUnit, NSubstitute, and async method
I'm doing some unit testing in C# using NUnit and NSubstitute. I have a class called Adapter, which has a method, GetTemplates(), I want to unit test. GetTemplates() uses httpclient, which I have mocked out using an interface.
The call in GetTemplates looks something like:
public async Task<List<Template>> GetTemplates()
{
//Code left out for simplificity.
var response = await _client.GetAsync($"GetTemplates");
if (!response.IsSuccessStatusCode)
{
throw new Exception();
}
}
I want _client.GetAsync to return a HttpResponseMessage with a HttpStatusCode.BadRequest so that I can test if the exception is being thrown.
The test method looks like:
[Test]
public void GetTemplate_ReturnBadRequestHttpMessage_ThrowException()
{
//Arrange.
var httpMessage = new HttpResponseMessage(HttpStatusCode.BadRequest);
_client.GetAsync("").Returns(Task.FromResult(httpMessage));
//Act.
var ex = Assert.ThrowsAsync<Exception>(async () => await _Adapter.GetSigningTemplates());
//Assert.
Assert.IsInstanceOf<Exception>(ex);
}
When the method has run, it returns
System.NullReferenceException: Object reference not set to an instance of an object.
What did I do wrong?
asp.net unit-testing async-await nunit nsubstitute
edited Nov 14 '18 at 11:04
Nkosi
112k16123190
asked Nov 14 '18 at 9:02
FrederikFrederik
638
add a comment |
I'm doing some unit testing in C# using NUnit and NSubstitute. I have a class called Adapter, which has a method, GetTemplates(), I want to unit test. GetTemplates() uses httpclient, which I have mocked out using an interface.
The call in GetTemplates looks something like:
public async Task<List<Template>> GetTemplates()
{
//Code left out for simplificity.
var response = await _client.GetAsync($"GetTemplates");
if (!response.IsSuccessStatusCode)
{
throw new Exception();
}
}
I want _client.GetAsync to return a HttpResponseMessage with a HttpStatusCode.BadRequest so that I can test if the exception is being thrown.
The test method looks like:
[Test]
public void GetTemplate_ReturnBadRequestHttpMessage_ThrowException()
{
//Arrange.
var httpMessage = new HttpResponseMessage(HttpStatusCode.BadRequest);
_client.GetAsync("").Returns(Task.FromResult(httpMessage));
//Act.
var ex = Assert.ThrowsAsync<Exception>(async () => await _Adapter.GetSigningTemplates());
//Assert.
Assert.IsInstanceOf<Exception>(ex);
}
When the method has run, it returns
System.NullReferenceException: Object reference not set to an instance of an object.
What did I do wrong?
asp.net unit-testing async-await nunit nsubstitute
edited Nov 14 '18 at 11:04
Nkosi
112k16123190
asked Nov 14 '18 at 9:02
FrederikFrederik
638
add a comment |
I'm doing some unit testing in C# using NUnit and NSubstitute. I have a class called Adapter, which has a method, GetTemplates(), I want to unit test. GetTemplates() uses httpclient, which I have mocked out using an interface.
The call in GetTemplates looks something like:
public async Task<List<Template>> GetTemplates()
{
//Code left out for simplificity.
var response = await _client.GetAsync($"GetTemplates");
if (!response.IsSuccessStatusCode)
{
throw new Exception();
}
}
I want _client.GetAsync to return a HttpResponseMessage with a HttpStatusCode.BadRequest so that I can test if the exception is being thrown.
The test method looks like:
[Test]
public void GetTemplate_ReturnBadRequestHttpMessage_ThrowException()
{
//Arrange.
var httpMessage = new HttpResponseMessage(HttpStatusCode.BadRequest);
_client.GetAsync("").Returns(Task.FromResult(httpMessage));
//Act.
var ex = Assert.ThrowsAsync<Exception>(async () => await _Adapter.GetSigningTemplates());
//Assert.
Assert.IsInstanceOf<Exception>(ex);
}
When the method has run, it returns
System.NullReferenceException: Object reference not set to an instance of an object.
What did I do wrong?
asp.net unit-testing async-await nunit nsubstitute
edited Nov 14 '18 at 11:04
Nkosi
112k16123190
asked Nov 14 '18 at 9:02
FrederikFrederik
638
I'm doing some unit testing in C# using NUnit and NSubstitute. I have a class called Adapter, which has a method, GetTemplates(), I want to unit test. GetTemplates() uses httpclient, which I have mocked out using an interface.
The call in GetTemplates looks something like:
public async Task<List<Template>> GetTemplates()
{
//Code left out for simplificity.
var response = await _client.GetAsync($"GetTemplates");
if (!response.IsSuccessStatusCode)
{
throw new Exception();
}
}
I want _client.GetAsync to return a HttpResponseMessage with a HttpStatusCode.BadRequest so that I can test if the exception is being thrown.
The test method looks like:
[Test]
public void GetTemplate_ReturnBadRequestHttpMessage_ThrowException()
{
//Arrange.
var httpMessage = new HttpResponseMessage(HttpStatusCode.BadRequest);
_client.GetAsync("").Returns(Task.FromResult(httpMessage));
//Act.
var ex = Assert.ThrowsAsync<Exception>(async () => await _Adapter.GetSigningTemplates());
//Assert.
Assert.IsInstanceOf<Exception>(ex);
}
When the method has run, it returns
System.NullReferenceException: Object reference not set to an instance of an object.
What did I do wrong?
asp.net unit-testing async-await nunit nsubstitute
asp.net unit-testing async-await nunit nsubstitute
edited Nov 14 '18 at 11:04
Nkosi
112k16123190
asked Nov 14 '18 at 9:02
FrederikFrederik
638
edited Nov 14 '18 at 11:04
Nkosi
112k16123190
asked Nov 14 '18 at 9:02
FrederikFrederik
638
edited Nov 14 '18 at 11:04
Nkosi
112k16123190
edited Nov 14 '18 at 11:04
Nkosi
112k16123190
edited Nov 14 '18 at 11:04
Nkosi
112k16123190
112k16123190
asked Nov 14 '18 at 9:02
FrederikFrederik
638
asked Nov 14 '18 at 9:02
FrederikFrederik
638
asked Nov 14 '18 at 9:02
FrederikFrederik
638
638
add a comment |
add a comment |
1 Answer
1
active
oldest
votes
That is because the arrangement of the mocked client does not match what is actually invoked when the test is exercised.
The client expects
var response = await _client.GetAsync($"GetTemplates");
but the setup is for
_client.GetAsync("")
note the different arguments passed. When mocks do not get exactly what was setup they usually return the default value of their return type, which in this case is null.
Change the test to use the expected parameter
_client.GetAsync($"GetTemplates").Returns(Task.FromResult(httpMessage));
Reference Return for specific args
or use an argument matcher
_client.GetAsync(Arg.Any<string>()).Returns(Task.FromResult(httpMessage));
Reference Argument matchers
answered Nov 14 '18 at 11:02
NkosiNkosi
112k16123190
Thanks, it's working. I also realized that I had a wrong order in the constructor.
– Frederik
Nov 14 '18 at 11:56
add a comment |
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1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
That is because the arrangement of the mocked client does not match what is actually invoked when the test is exercised.
The client expects
var response = await _client.GetAsync($"GetTemplates");
but the setup is for
_client.GetAsync("")
note the different arguments passed. When mocks do not get exactly what was setup they usually return the default value of their return type, which in this case is null.
Change the test to use the expected parameter
_client.GetAsync($"GetTemplates").Returns(Task.FromResult(httpMessage));
Reference Return for specific args
or use an argument matcher
_client.GetAsync(Arg.Any<string>()).Returns(Task.FromResult(httpMessage));
Reference Argument matchers
answered Nov 14 '18 at 11:02
NkosiNkosi
112k16123190
Thanks, it's working. I also realized that I had a wrong order in the constructor.
– Frederik
Nov 14 '18 at 11:56
add a comment |
That is because the arrangement of the mocked client does not match what is actually invoked when the test is exercised.
The client expects
var response = await _client.GetAsync($"GetTemplates");
but the setup is for
_client.GetAsync("")
note the different arguments passed. When mocks do not get exactly what was setup they usually return the default value of their return type, which in this case is null.
Change the test to use the expected parameter
_client.GetAsync($"GetTemplates").Returns(Task.FromResult(httpMessage));
Reference Return for specific args
or use an argument matcher
_client.GetAsync(Arg.Any<string>()).Returns(Task.FromResult(httpMessage));
Reference Argument matchers
answered Nov 14 '18 at 11:02
NkosiNkosi
112k16123190
Thanks, it's working. I also realized that I had a wrong order in the constructor.
– Frederik
Nov 14 '18 at 11:56
add a comment |
That is because the arrangement of the mocked client does not match what is actually invoked when the test is exercised.
The client expects
var response = await _client.GetAsync($"GetTemplates");
but the setup is for
_client.GetAsync("")
note the different arguments passed. When mocks do not get exactly what was setup they usually return the default value of their return type, which in this case is null.
Change the test to use the expected parameter
_client.GetAsync($"GetTemplates").Returns(Task.FromResult(httpMessage));
Reference Return for specific args
or use an argument matcher
_client.GetAsync(Arg.Any<string>()).Returns(Task.FromResult(httpMessage));
Reference Argument matchers
answered Nov 14 '18 at 11:02
NkosiNkosi
112k16123190
That is because the arrangement of the mocked client does not match what is actually invoked when the test is exercised.
The client expects
var response = await _client.GetAsync($"GetTemplates");
but the setup is for
_client.GetAsync("")
note the different arguments passed. When mocks do not get exactly what was setup they usually return the default value of their return type, which in this case is null.
Change the test to use the expected parameter
_client.GetAsync($"GetTemplates").Returns(Task.FromResult(httpMessage));
Reference Return for specific args
or use an argument matcher
_client.GetAsync(Arg.Any<string>()).Returns(Task.FromResult(httpMessage));
Reference Argument matchers
answered Nov 14 '18 at 11:02
NkosiNkosi
112k16123190
edited Nov 14 '18 at 11:08
answered Nov 14 '18 at 11:02
NkosiNkosi
112k16123190
answered Nov 14 '18 at 11:02
NkosiNkosi
112k16123190
answered Nov 14 '18 at 11:02
NkosiNkosi
112k16123190
112k16123190
Thanks, it's working. I also realized that I had a wrong order in the constructor.
– Frederik
Nov 14 '18 at 11:56
add a comment |
Thanks, it's working. I also realized that I had a wrong order in the constructor.
– Frederik
Nov 14 '18 at 11:56
Thanks, it's working. I also realized that I had a wrong order in the constructor.
– Frederik
Nov 14 '18 at 11:56
Thanks, it's working. I also realized that I had a wrong order in the constructor.
– Frederik
Nov 14 '18 at 11:56
add a comment |
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