Mock IHttpContextAccessor in Unit Tests

Question

I have a method to get header value using IHttpContextAccessor

public class HeaderConfiguration : IHeaderConfiguration {     public HeaderConfiguration()     {      }      public string GetTenantId(IHttpContextAccessor httpContextAccessor)     {         return httpContextAccessor.HttpContext.Request.Headers["Tenant-ID"].ToString();     } } 

I am testing GetBookByBookId method

Let's say the method looks like this:

public class Book {     private readonly IHttpContextAccessor _httpContextAccessor;     private IHeaderConfiguration _headerConfiguration;     private string _tenantID;      public Book(IHeaderConfiguration headerConfiguration, IHttpContextAccessor httpContextAccessor){         var headerConfig = new HeaderConfiguration();         _httpContextAccessor = httpContextAccessor;         _tenantID = headerConfig.GetTenantId(_httpContextAccessor);     }      public Task<List<BookModel>> GetBookByBookId(string id){         //do something with the _tenantId         //...     } } 

Here's my unit test for GetBookByBookId method

[Fact] public void test_GetBookByBookId() {     //Arrange      //Mock IHttpContextAccessor     var mockHttpContextAccessor = new Mock<IHttpContextAccessor>();      mockHttpContextAccessor.Setup(req => req.HttpContext.Request.Headers["Tenant-ID"].ToString()).Returns(It.IsAny<string>());     //Mock HeaderConfiguration     var mockHeaderConfiguration = new Mock<IHeaderConfiguration>();     mockHeaderConfiguration.Setup(x => x.GetTenantId(mockHttpContextAccessor.Object)).Returns(It.IsAny<string>());      var book = new Book( mockHttpContextAccessor.Object, mockHeaderConfiguration.Object);      var bookId = "100";      //Act     var result = book.GetBookByBookId(bookId);      //Assert     result.Result.Should().NotBeNull().And.         BeOfType<List<BookModel>>(); } 

But for this line:

mockHttpContextAccessor.Setup(req => req.HttpContext.Request.Headers["Tenant-ID"].ToString()).Returns(It.IsAny<string>()); 

It says

System.NotSupportedException: 'Type to mock must be an interface or an abstract or non-sealed class. '

I was wondering what's the proper way to mock IHttpContextAccessor with header value?

Answer 1

You can use the DefaultHttpContext as a backing for the IHttpContextAccessor.HttpContext. Saves you having to set-up too many things

Next you cannot use It.IsAny<string>() as a Returns result. They were meant to be used in the set up expressions alone.

Check the refactor

[Fact] public async Task test_GetBookByBookId() {     //Arrange      //Mock IHttpContextAccessor     var mockHttpContextAccessor = new Mock<IHttpContextAccessor>();     var context = new DefaultHttpContext();     var fakeTenantId = "abcd";     context.Request.Headers["Tenant-ID"] = fakeTenantId;     mockHttpContextAccessor.Setup(_ => _.HttpContext).Returns(context);     //Mock HeaderConfiguration     var mockHeaderConfiguration = new Mock<IHeaderConfiguration>();     mockHeaderConfiguration         .Setup(_ => _.GetTenantId(It.IsAny<IHttpContextAccessor>()))         .Returns(fakeTenantId);      var book = new Book(mockHttpContextAccessor.Object, mockHeaderConfiguration.Object);      var bookId = "100";      //Act     var result = await book.GetBookByBookId(bookId);      //Assert     result.Should().NotBeNull().And.         BeOfType<List<BookModel>>(); } 

There may also be an issue with the Class Under Test as it is manually initializing the HeaderConfiguration when it should actually be explicitly injected.

public Book(IHeaderConfiguration headerConfiguration, IHttpContextAccessor httpContextAccessor) {     _httpContextAccessor = httpContextAccessor;     _tenantID = headerConfiguration.GetTenantId(_httpContextAccessor); } 

Answer 2

In my scenario I had to mock IHttpContextAccessor and access the inner request url bits.
I'm sharing it here because I spent a decent amount of time figuring this out and hopefully it'll help someone.

readonly Mock<IHttpContextAccessor> _HttpContextAccessor =    new Mock<IHttpContextAccessor>(MockBehavior.Strict);  void SetupHttpContextAccessorWithUrl(string currentUrl) {   var httpContext = new DefaultHttpContext();   setRequestUrl(httpContext.Request, currentUrl);    _HttpContextAccessor     .SetupGet(accessor => accessor.HttpContext)     .Returns(httpContext);    static void setRequestUrl(HttpRequest httpRequest, string url)   {     UriHelper       .FromAbsolute(url, out var scheme, out var host, out var path, out var query,          fragment: out var _);      httpRequest.Scheme = scheme;     httpRequest.Host = host;     httpRequest.Path = path;     httpRequest.QueryString = query;   } }