Creating multiple regular expression requests in rapid succession yields same result (.NET framework)

[MagnusMikkelsen]

The test below (usually) fails in .NET framework fails in .NET framework, but not in core.

The underlying reason for this is that Xeger is used in autofixture without injecting an object of type Random, and Xeger uses new Random() - without injecting a seed.

The test passes, in .NET Core, because new Random() internally generates a unique seed.
However, as you probably know, in framework, it uses tick count as seed.

I haven't created a pr, because I didn't know where to do it to - does it make sense to create a pr with a failing test to master?

And I don't know if it should be fixed here in AF, or a pr should be created in the Fare repo.

What do you think? I'd like to fix this - but I'm not sure how to proceed...

        [Theory]
        [InlineData(@"^[A-Z]{27}$")]
        public void CreateTwoWithRegularExpressionRequestReturnsDifferentResults(string pattern)
        {
            // Arrange
            var sut = new RegularExpressionGenerator();
            
            var request = new RegularExpressionRequest(pattern);
            var dummyContext = new DelegatingSpecimenContext();
            // Act
            var result1 = sut.Create(request, dummyContext);
            var result2 = sut.Create(request, dummyContext);
            
            // Assert
            Assert.NotEqual(result1, result2);
        }

[moodmosaic]

Thank you for reporting this 👍 It looks like the issue can be fixed in Fare, as per moodmosaic/Fare#26 (comment).

[MagnusMikkelsen]

👍

[moodmosaic]

Using a singleton-scoped (e.g. private readonly or perhaps private static readonly) Random instance supplied in

AutoFixture/Src/AutoFixture/RegularExpressionGenerator.cs

Line 40 in d3e14a8

string regex = new Xeger(pattern).Generate();

as per this Xeger constructor overload should fix the issue.

[MagnusMikkelsen]

Using a singleton-scoped (e.g. private readonly or perhaps private static readonly) Random instance...
... should fix the issue.

I think that's what I'm trying to do in #1187 ?

AutoFixture/Src/AutoFixture/RegularExpressionGenerator.cs

Line 52 in 02f6b7c

string regex = new Xeger(pattern, this.random).Generate();