I have read through FluenAssertions Extensibility page, but I still cannot understand how to create a Should().BeEquivalentTo() comparison method for collection of objects, if I already implemented Should().BeEquivalentTo() for an object, while preserving the all other assertion methods for the same collection.
Here is a simplified example: The class that I want to check:
public class CalculationResult
{
public DateTime Date { get; set; }
public int Id { get; set; }
public bool CalcState { get; set; }
public double Result { get; set; }
}
The class I convert a table row in Specflow test suite
public class CalcResultBdd
{
public DateTime Date { get; set; }
public double Result { get; set; }
}
The class to class comparison class is:
public class CalculationResultAssertions : ReferenceTypeAssertions<CalculationResult, CalculationResultAssertions>
{
public CalculationResultAssertions(CalculationResult instance)
{
Subject = instance;
}
protected override string Identifier => "CalculationResult";
[CustomAssertion]
public AndConstraint<CalculationResultAssertions> BeEquivalentTo(
CalcResultBdd expectedResult,
double precision = 0.001,
string because = "",
params object[] becauseArgs)
{
Execute.Assertion.
BecauseOf(because, becauseArgs).
ForCondition(expectedResult != null).
FailWith("You cannot assert that calculation result is correct if you do not pass a proper object").
Then.
ForCondition(precision >= 0).
FailWith("You cannot compare double values if you provide negative precision").
Then.
Given(() => Subject).
ForCondition(s => s.CalcState).
FailWith("Expected CalcState to be \"true\"").
Then.
ForCondition(s => s.Date == expectedResult.Date).
FailWith(
"Expected Date to be {0}{reason}, but found {1}",
_ => expectedResult.Date.ToString("yyyy-MM-dd"),
s => s.Date.ToString("yyyy-MM-dd")).
Then.
ForCondition(s => Math.Abs(s.Result - expectedResult.Result) <= precision).
FailWith(
"Expected Result to be {0} with precision {1}{reason}, but found {2}",
_ => expectedResult.Result,
_ => precision,
s => s.Result);
return new AndConstraint<CalculationResultAssertions>(this);
}
}
Static class linking FluentAssertions and custom assertions class:
public static class AssertionExtensions
{
public static CalculationResultAssertions Should(this CalculationResult instance)
{
return new CalculationResultAssertions(instance);
}
}
If I run the following, without redefining the BeEquivalentTo for List<CalculationResult>
List<CalculationResult> actualResults = /* getting results here */
actualResults.Should().BeEquivalentTo(new CalcResultBdd[] { /* expected results here */ })
FluentAssertions will use build-in structural comparison instead of custom comparison. Is it possible for me to change something in my code so that Fluent assertions uses the custom comparison instead?
