analyzerTestFixture.md

Analyzer Test Fixture

The BaseAnalyzerTestFixture provides a base implementation of a test fixture that tests a specific diagnostic rule, as returned by TestedDiagnosticRule.

By default, TestedDiagnosticRule will be the DiagnosticDescriptor returned by the DiagnosticDescriptorStorage property. The rule ID is detected from the name of the test fixture type.

For example, a test fixture for the CS0101 rule should be named CS0101..., which would be successfully detected. Otherwise, the property TestedDiagnosticRule should be overridden to return the actual DiagnotsicDescriptor that will be accounted.

Below are listed templates for using the abstracted test fixtures.

Diagnostic Test Fixture Template

An example of defining a diagnostic test fixture using the Gu.Roslyn.Asserts framework:

using Gu.Roslyn.Asserts;
using Microsoft.CodeAnalysis.Diagnostics;
using Microsoft.VisualStudio.TestTools.UnitTesting;
using RoseLynn.Analyzers;
using RoseLynn.Testing;

public abstract class BaseExampleDiagnosticTests<TAnalyzer> : BaseDiagnosticTests
    where TAnalyzer : DiagnosticAnalyzer, new()
{
    protected ExpectedDiagnostic ExpectedDiagnostic => ExpectedDiagnostic.Create(TestedDiagnosticRule);
    protected sealed override DiagnosticDescriptorStorageBase DiagnosticDescriptorStorage => ExampleDiagnosticDescriptorStorage.Instance;

    protected sealed override DiagnosticAnalyzer GetNewDiagnosticAnalyzerInstance() => new TAnalyzer();
    protected override UsingsProviderBase GetNewUsingsProviderInstance() => ExampleUsingsProvider.Instance;

    protected override void ValidateCode(string testCode)
    {
        RoslynAssert.Valid(GetNewDiagnosticAnalyzerInstance(), testCode);
    }
    protected override void AssertDiagnostics(string testCode)
    {
        RoslynAssert.Diagnostics(GetNewDiagnosticAnalyzerInstance(), ExpectedDiagnostic, testCode);
    }
}

Code Fix Test Fixture Template

An example of defining a code fix test fixture using the Microsoft.CodeAnalysis.Testing framework:

using Microsoft.CodeAnalysis.Diagnostics;
using Microsoft.VisualStudio.TestTools.UnitTesting;
using RoseLynn.Analyzers;
using RoseLynn.Testing;
using System.Threading.Tasks;

public abstract class BaseCodeFixTests<TAnalyzer, TCodeFix> : BaseCodeFixDiagnosticTests<TAnalyzer, TCodeFix>
    where TAnalyzer : DiagnosticAnalyzer, new()
    where TCodeFix : ExampleCodeFixProvider, new()
{
    protected sealed override DiagnosticDescriptorStorageBase DiagnosticDescriptorStorage => ExampleDiagnosticDescriptorStorage.Instance;

    protected sealed override async Task VerifyCodeFixAsync(string markupCode, string expected, int codeActionIndex)
    {
        await CSharpCodeFixVerifier<TAnalyzer, TCodeFix>.VerifyCodeFixAsync(markupCode, expected, codeActionIndex);
    }
}

Note: The CSharpCodeFixVerifier<TAnalyzer, TCodeFix> type is an automatically generated type from the code analyzer template in Visual Studio 2019.