Asserting Result Objects

With the package FluentResults.Extensions.FluentAssertions you can assert result objects in an elegant way.

Asserting Methods

Result should be failed

var actualResult = Result.Fail("Error 1");
actualResult.Should().BeFailure();

Result should be success

var actualResult = Result.Ok();
actualResult.Should().BeSuccess();

Result should have specific value

var actualResult = Result.Ok(1);
actualResult.Should().HaveValue(1);

Result should have a specific reason

var actualResult = Result.Ok(1);
actualResult.Should().HaveReason("Error 1");
actualResult.Should().HaveReason<CustomError>("Error 2");
actualResult.Should().HaveReason(new { ... });

If you don't set an ErrorMessageComparison via parameter then the default comparison is used. The default comparison is set globally via FluentResultAssertionsConfig.ErrorMessageComparison which is by default ErrorMessageComparisonLogics.Equal. The comparison ErrorMessageComparisonLogics.ActualContainsExpected which is the default comparison logic for FluentResults.Extensions.FluentAssertions < v2.0 is also available and can be set globally or via parameter. If you need some another custom comparison logic feel free to set your own. The comparison is only a Func<string, string, bool> with the parameters actual error message and expected error message.

var actualResult = Result.Ok();
actualResult.Should().HaveReason("Error 1", ErrorMessageComparisonLogics.ActualContainsExpected);

Reason should have specific metadata

With the That property you switch to the reason context to assert the reason.

var actualResult = Result.Fail(new CustomError().WithMetadata("ErrorCode", "123"));
actualResult.Should().HaveReason("Error 1")
                     .That.HaveMetadata("ErrorCode", "123");

Reason should satisfy conditions

var actualResult = Result.Fail(new CustomError() { ErrorCode = "123" });
actualResult.Should().HaveReason("Error 1")
                     .That.Satisfy<CustomError>(r => r.ErrorCode.Should().Be("123"));

Result should satisfy conditions

var actualResult = Result.Ok(1);
actualResult.Should().BeFailure()
                     .And.Satisfy(result => {
                         result.Errors.Should().ContainEquivalentOf(new Error("Error 1"));
                      });