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Unit Testing of Analyzers

NuGet Package​

dotnet add package roslynator.testing.csharp.xunit

or

dotnet add package roslynator.testing.csharp.mstest

Example: Test Analyzer With Code Fix​

using Roslynator.Testing.CSharp.Xunit;
using Xunit;

public class AccessibilityModifiersTests
    : XunitDiagnosticVerifier<AccessibilityModifiersAnalyzer, AccessibilityModifiersCodeFixProvider>
{
    public override DiagnosticDescriptor Descriptor { get; } = AccessibilityModifiersAnalyzer.Descriptor;

    [Fact]
    public async Task Test()
    {
        await VerifyDiagnosticAndFixAsync(
            source: @"
namespace N
{
    class [|C|]
    {
    }
}
",
            expectedSource: @"
namespace N
{
    internal class C
    {
    }
}
",
            options: Options.AddConfigOption("roslynator_accessibility_modifiers", "explicit"));
    }
}

Example: Test Analyzer Without Code Fix​

Use EmptyCodeFixProvider in tests of analyzers without a code fix.

using Roslynator.Testing.CSharp.Xunit;
using Xunit;

public class UnusedParameterTests
    : XunitDiagnosticVerifier<UnusedParameterAnalyzer, EmptyCodeFixProvider>
{
    public override DiagnosticDescriptor Descriptor { get; } = DiagnosticDescriptors.UnusedParameter;

    [Fact]
    public async Task Test()
    {
        await VerifyDiagnosticAsync(
            source: @"
class C
{
    void M([|object p|])
    {
    }
}
"
);
    }
}

How to Mark Diagnostic's Location​

Diagnostic's location is marked directly in a test code using [| and |] tokens.

How to Add Config Options​

Each test method has parameter options of type TestOptions:

options: Options.AddConfigOption("option_key", "option_value")