Below is my class with a static readonly field:
public class Stats
{
public static readonly int MinPoints = 900;
public static readonly int MaxPoints = 1500;
public int Points { get; }
private Stats()
{
}
public Stats(int points) : this()
{
if (points < Stats.MinPoints || points > Stats.MaxPoints)
{
throw new InvalidOperationException();
}
Points = points;
}
}
When compiling, I don't have any errors. But when I try to instanciate a Stats
object, I'm getting a TypeInitializationException
. When replacing PlayerStatistics.MaxPoints
in the constructor with its proper value, the code works.
Here is the error I get when unit testing the constructor:
Expected a <System.InvalidOperationException> to be thrown, but found <System.TypeInitializationException>: "
"System.TypeInitializationException with message "The type initializer for 'League.Domain.Player.Stats' threw an exception."
at League.Domain.Player.Stats..ctor(Int32 points) in C:\dev\repos\League\League.Domain\Player\Stats.cs:line 24
at League.Tests.StatsSpecs.<>c__DisplayClass1_0.<Create_stats_with_incorrect_points_should_throw_exception>b__0() in C:\dev\repos\League\League.Tests\StatsSpecs.cs:line 36
at FluentAssertions.Specialized.ActionAssertions.InvokeSubject()
at FluentAssertions.Specialized.DelegateAssertions`1.InvokeSubjectWithInterception()
.
at FluentAssertions.Execution.XUnit2TestFramework.Throw(String message)
at FluentAssertions.Execution.TestFrameworkProvider.Throw(String message)
at FluentAssertions.Execution.DefaultAssertionStrategy.HandleFailure(String message)
at FluentAssertions.Execution.AssertionScope.FailWith(Func`1 failReasonFunc)
at FluentAssertions.Execution.AssertionScope.FailWith(Func`1 failReasonFunc)
at FluentAssertions.Execution.AssertionScope.FailWith(String message, Object[] args)
at FluentAssertions.Specialized.DelegateAssertions`1.Throw[TException](Exception exception, String because, Object[] becauseArgs)
at FluentAssertions.Specialized.DelegateAssertions`1.Throw[TException](String because, Object[] becauseArgs)
at League.Tests.StatsSpecs.Create_stats_with_incorrect_points_should_throw_exception(Int32 points) in C:\dev\repos\League\League.Tests\StatsSpecs.cs:line 38
And here is my unit test, written with XUnit:
[Theory]
[InlineData(899)]
[InlineData(1501)]
public void Create_stats_with_incorrect_points_should_throw_exception(int points)
{
Action action = () => new Stats(points);
action.Should().Throw<InvalidOperationException>();
}
Is there a way to still use the static readonly field in the constructor?
I was able to find the solution...
I tried to simplify my code too much, and omitted to put a line in my class:
public class Stats
{
// I didn't put this line of code, so it was working without it
public static readonly Stats New = new Stats(1000);
public static readonly int MinPoints = 900;
public static readonly int MaxPoints = 1500;
public int Points { get; }
private Stats()
{
}
public Stats(int points) : this()
{
if (points < Stats.MinPoints || points > Stats.MaxPoints)
{
throw new InvalidOperationException();
}
Points = points;
}
}
So as mentioned Dmitry Bychenko, static readonly field are not assign at compile time. So if I were to put these lines before the line I ommited, like this:
public static readonly int MinPoints = 900;
public static readonly int MaxPoints = 1500;
public static readonly Stats New = new Stats(1000);
It would work fine.
And thanks to his comment, using const instead of a static readonly field make my code work, at any place I put these these two constants in my class.
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