C# – Passing single value to params argument in NUnit TestCase

cnunitparameter-passingunit testing

I have the following test:

[ExpectedException(typeof(ParametersParseException))]
[TestCase("param1")]
[TestCase("param1", "param2")]
[TestCase("param1", "param2", "param3", "optParam4", "optParam5", "some extra parameter")]
public void Parse_InvalidParametersNumber_ThrowsException(params string[] args)
{
    new ParametersParser(args).Parse();
}

The first TestCase (obviously) fails with the following error:

System.ArgumentException : Object of type 'System.String' 
cannot be converted to type 'System.String[]'.

I tried to replace the TestCase definition with this one:

[TestCase(new[] { param1 })]

but now I get the following compilation error:

error CS0182: An attribute argument must be a constant expression, typeof expression or array creation expression of an attribute parameter type

My solution for now is moving the 'one parameter' case to a different test method.

Still, is there a way to get this test to run the same way as the others?

Best Answer

One way could be to use TestCaseSource, and have a method that returns each parameter set, instead of using TestCase.

Related Solutions

C# – How to pass objects into an attribute constructor

The values into attributes are limited to simple types; for example, basic constants (including strings) and typeof... you can't use new or other more complex code. In short; you can't do this. You can give it the type though:

[PropertyValidation(typeof(NullOrEmptyValidatorScheme)]

i.e. the PropertyValidation ctor takes a Type, and use Activator.CreateInstance inside the code to create the object. Note that you should ideally just store the string internally (AssemblyQualifiedName).

From ECMA 334v4:

§24.1.3 Attribute parameter types

The types of positional and named parameters for an attribute class are limited to the attribute parameter types, which are:

One of the following types: bool, byte, char, double, float, int, long, short, string.

The type object.

The type System.Type.

An enum type, provided it has public accessibility and the types in which it is nested (if any) also have public accessibility.

Single-dimensional arrays of the above types.

and

§24.2 Attribute specification

...

An expression E is an attribute-argument-expression if all of the following statements are true:

The type of E is an attribute parameter type (§24.1.3).

At compile-time, the value of E can be resolved to one of the following:

A constant value.

A typeof-expression (§14.5.11) specifying a non-generic type, a closed constructed type (§25.5.2), or an unbound generic type (§25.5).

A one-dimensional array of attribute-argument-expressions.

C# – DisplayName attribute from Resources

If you use MVC 3 and .NET 4, you can use the new Display attribute in the System.ComponentModel.DataAnnotations namespace. This attribute replaces the DisplayName attribute and provides much more functionality, including localization support.

In your case, you would use it like this:

public class MyModel
{
    [Required]
    [Display(Name = "labelForName", ResourceType = typeof(Resources.Resources))]
    public string name{ get; set; }
}

As a side note, this attribute will not work with resources inside App_GlobalResources or App_LocalResources. This has to do with the custom tool (GlobalResourceProxyGenerator) these resources use. Instead make sure your resource file is set to 'Embedded resource' and use the 'ResXFileCodeGenerator' custom tool.

(As a further side note, you shouldn't be using App_GlobalResources or App_LocalResources with MVC. You can read more about why this is the case here)

Best Answer

Related Solutions

C# – How to pass objects into an attribute constructor

C# – DisplayName attribute from Resources

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