parameterised-nunit.md

NUnit Parameterised Tests

UseParameters()

UseParameters() controls what parameters are used when naming files.

Verify.NUnit automatically detects the method parameters. So UseParameters() is not required unless using custom parameters.

If not all parameters are required, a subset can be passed in. In this scenario, the parameters passed in will match with the method parameter names from the start. For example the following will result in a file named ParametersSample.UseParametersSubSet_arg1=Value1_arg2=Value2.verified.txt

[TestCase("Value1", "Value2", "Value3")]
public Task UseParametersSubSet(string arg1, string arg2, string arg3)
{
    var somethingToVerify = $"{arg1} {arg2} {arg3} some text";
    return Verify(somethingToVerify)
        .UseParameters(arg1, arg2);
}

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If the number of parameters passed to UseParameters() is greater than the number of parameters in the test method, an exception will be thrown.

TestCase

[TestCase("Value1")]
[TestCase("Value2")]
public Task TestCaseUsage(string arg) =>
    Verify(arg);

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TestFixtureSourceUsage

When using a TestFixtureSource the name provided by NUnit will be as the TestMethodName.

[TestFixtureSource(nameof(FixtureArgs))]
public class TestFixtureSourceUsage(string arg1, int arg2)
{
    [Test]
    public Task Test() =>
        Verify(
            new
            {
                arg1,
                arg2
            });

    static object[] FixtureArgs =
    [
        new object[]
        {
            "Value1",
            1
        },
        new object[]
        {
            "Value2",
            2
        }
    ];
}

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Produces:

• TestFixtureSourceUsage.Test_arg1=Value1_arg2=1.verified.txt
• TestFixtureSourceUsage.Test_arg1=Value2_arg2=2.verified.txt

Unknown parameter types

For unknown types the parameter information cannot be derived. In these scenarios ToString() is used. To use custom text for a parameter use NameForParameter().

public class ComplexParametersSample
{
    [ModuleInitializer]
    public static void Initialize() =>
        VerifierSettings.NameForParameter<ComplexData>(_ => _.Value);

    [TestCaseSource(nameof(GetData))]
    public Task ComplexTestCaseSource(ComplexData arg) =>
        Verify(arg);

    public static IEnumerable<object[]> GetData()
    {
        yield return
        [
            new ComplexData("Value1")
        ];
        yield return
        [
            new ComplexData("Value2")
        ];
    }

    public record ComplexData(string Value);
}

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Overriding text used for parameters

UseTextForParameters() can be used to override the substitution text used for the {Parameters} part of the file convention.

{Directory}/{TestClassName}.{TestMethodName}_{Parameters}_{UniqueFor1}_{UniqueFor2}_{UniqueForX}.verified.{extension}

The below samples produce:

For the instance case:

• TheTest.UseTextForParameters_Value1.verified.txt
• TheTest.UseTextForParameters_Value2.verified.txt

For the fluent case:

• TheTest.UseTextForParametersFluent_Value1.verified.txt
• TheTest.UseTextForParametersFluent_Value2.verified.txt

Instance

[TestCase("Value1")]
[TestCase("Value2")]
public Task UseTextForParameters(string arg)
{
    var settings = new VerifySettings();
    settings.UseTextForParameters(arg);
    return Verify(arg + "UseTextForParameters", settings);
}

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Fluent

[TestCase("Value1")]
[TestCase("Value2")]
public Task UseTextForParametersFluent(string arg) =>
    Verify(arg + "UseTextForParametersFluent")
        .UseTextForParameters(arg);

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Ignore parameters for verified filename

By default, Verify expects every parameterized case to have a unique file name with the parameters appended to the file name. This behavior can be overridden by using IgnoreParametersForVerified(). In this case, the verified file name does not contain the parameter values, meaning it is the same for each testcase.

IgnoreParametersForVerified accepts an array for passing through the parameters. These values are passed to UseParameters. This is required for MSTest, and xUnit. Parameters should not be passed for NUnit, TUnit and Fixie since they are automatically detected.

The below samples produce:

For the instance case:

• NamerTests.IgnoreParametersForVerified_arg=One.received.txt
• NamerTests.IgnoreParametersForVerified_arg=Two.received.txt
• NamerTests.IgnoreParametersForVerified.verified.txt

For the fluent case:

• NamerTests.IgnoreParametersForVerifiedFluent_arg=One.received.txt
• NamerTests.IgnoreParametersForVerifiedFluent_arg=Two.received.txt
• NamerTests.IgnoreParametersForVerifiedFluent.verified.txt

Instance

[TestCase("One")]
[TestCase("Two")]
public Task IgnoreParametersForVerified(string arg)
{
    var settings = new VerifySettings();
    settings.IgnoreParametersForVerified();
    return Verify("value", settings);
}

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Fluent

[TestCase("One")]
[TestCase("Two")]
public Task IgnoreParametersForVerifiedFluent(string arg) =>
    Verify("value")
        .IgnoreParametersForVerified();

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IgnoreParametersForVerified with override parameters

The parameters passed to IgnoreParametersForVerified can be used pass custom parameters to UseParameters.

Instance

[TestCase("One")]
[TestCase("Two")]
public Task IgnoreParametersForVerifiedCustomParams(string arg)
{
    var settings = new VerifySettings();
    settings.IgnoreParametersForVerified($"Number{arg}");
    return Verify("value", settings);
}

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Fluent

[TestCase("One")]
[TestCase("Two")]
public Task IgnoreParametersForVerifiedCustomParamsFluent(string arg) =>
    Verify("value")
        .IgnoreParametersForVerified($"Number{arg}");

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Hashing parameters

Parameters can be hashed as an alternative to being stringified. This is useful when the parameters are large and could potentially generate file names that exceed allowances of the OS.

Hashing parameter is achieved by using HashParameters.

Overriding text used for parameters is respected when generating the hash.

XxHash64 is used to perform the hash.

Instance

[TestCase("Value1")]
[TestCase("Value2")]
public Task HashParametersUsage(string arg)
{
    var settings = new VerifySettings();
    settings.HashParameters();
    return Verify(arg, settings);
}

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Fluent

[TestCase("Value1")]
[TestCase("Value2")]
public Task HashParametersUsageFluent(string arg) =>
    Verify(arg)
        .HashParameters();

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