🐛 Fixture cannot create Byte Array with RegularExpressionAttribute

[RonSijm]

when a Byte Array has a RegularExpressionAttribute, the Fixture seems to treat it as string.

Scenario

public class TestFixtureCanCreateByteArray
{
    [Fact]
    public void CanCreateByteArray()
    {
        var fixture = new Fixture();
        var result = fixture.Create<TestClass>();
    }
}

public class TestClass
{
    [System.ComponentModel.DataAnnotations.RegularExpression(@"^(?:[A-Za-z0-9+/]{4})*(?:[A-Za-z0-9+/]{2}==|[A-Za-z0-9+/]{3}=)?$")]
    public byte[] invoice { get; set; }
}

Expected Behavior

An array of bytes is generated matching the regular expression

Actual Behavior

Inner exception messages:
	System.ArgumentException: Object of type 'System.String' cannot be converted to type 'System.Byte[]'.

Tasks

• Updated all AutoFixture and related libraries
• Confirmed in support forums if behavior is expected

More Information

I encountered this after generating a client library based on a swagger for Hubspot.
Swagger API: https://api.hubspot.com/api-catalog-public/v1/apis/crm/v3/extensions/accounting line 1407

  "InvoicePdfResponse" : {
    "required" : [ "invoice" ],
    "type" : "object",
    "properties" : {
      "@result" : {
        "type" : "string",
        "description" : "Designates if the response is a success ('OK') or failure ('ERR').",
        "example" : "OK",
        "enum" : [ "OK", "ERR" ]
      },
      "invoice" : {
        "pattern" : "^(?:[A-Za-z0-9+/]{4})*(?:[A-Za-z0-9+/]{2}==|[A-Za-z0-9+/]{3}=)?$",
        "type" : "string",
        "description" : "The bytes of the invoice PDF.",
        "format" : "byte"
      }
    },
    "description" : "A response that contains the PDF of an invoice"
  },

[aivascu]

@RonSijm thank you for raising this, however I could not find any information about the RegularExpression attribute supporting neither byte nor char arrays.
I wrote these tests to check and it doesn't seem that the attribute can support values of the required types. Perhaps you're using a framework that implements custom validation support?

[Theory]
[InlineData("[0-9]+", new [] {'0', '1'})]
[InlineData("[A-Z]+", new [] {'A', 'Z'})]
[InlineData("[a-z]+", new [] {'d', 'c'})]
public void AttributeValidatesByteArray(string pattern, char[] value)
{
    var attribute = new RegularExpressionAttribute(pattern);
    object bytes = value.Select(x => (byte)x).ToArray();
    Validator.ValidateValue(bytes, new ValidationContext(this, null, null), new[] { attribute });
}

[Theory]
[InlineData("[0-9]+", new [] {'0', '1'})]
[InlineData("[A-Z]+", new [] {'A', 'Z'})]
[InlineData("[a-z]+", new [] {'d', 'c'})]
public void AttributeValidatesCharArray(string pattern, char[] value)
{
    var attribute = new RegularExpressionAttribute(pattern);
    Validator.ValidateValue(value, new ValidationContext(this, null, null), new[] { attribute });
}

[Theory]
[InlineData("[0-9]+", "01")]
[InlineData("[A-Z]+", "AZ")]
[InlineData("[a-z]+", "dc")]
public void AttributeValidatesString(string pattern, string value)
{
    var attribute = new RegularExpressionAttribute(pattern);
    Validator.ValidateValue(value, new ValidationContext(this, null, null), new[] { attribute });
}

[RonSijm]

I'm not 100% sure what the attribute is supposed to do (As I mentioned, I'm implementing a client based on the hubspot swagger link that I provided, but besides that I'm not familiar with what the endpoint expects)

If I had to guess, maybe the string form of the byte array is supposed to match the regex

Perhaps you're using a framework that implements custom validation support?

I used NSwag toolchain v13.11.3.0 to generate the client library. I don't know if the attribute is actually going to be validated by anything. I guess NSwag just added it because the pattern is specified in the swagger file.

In msdn: https://docs.microsoft.com/en-us/dotnet/api/system.componentmodel.dataannotations.regularexpressionattribute?view=net-6.0 their example seems to show:

[RegularExpression(@"^[a-zA-Z''-'\s]{1,40}$", ErrorMessage = "Characters are not allowed.")]
public object FirstName;

Using it on an object, and not specifically a string (Which I'm also not sure of of how that's supposed to work...

Anyways, if it's not valid, I suppose Fixture should just ignore it, instead of throw