SetupShouldBeUsedOnlyForOverridableMembersAnalyzer.cs

using Microsoft.CodeAnalysis.Operations;

namespace Moq.Analyzers;

/// <summary>
/// Setup should be used only for overridable members.
/// </summary>
[DiagnosticAnalyzer(LanguageNames.CSharp)]
public class SetupShouldBeUsedOnlyForOverridableMembersAnalyzer : MoqDiagnosticAnalyzerBase
{
    private static readonly LocalizableString Title = "Moq: Invalid setup parameter";
    private static readonly LocalizableString Message = "Setup should be used only for overridable members, but '{0}' is not overridable";
    private static readonly LocalizableString Description = "Setup should be used only for overridable members.";

    private static readonly DiagnosticDescriptor Rule = new(
        DiagnosticIds.SetupOnlyUsedForOverridableMembers,
        Title,
        Message,
        DiagnosticCategory.Correctness,
        DiagnosticSeverity.Error,
        isEnabledByDefault: true,
        description: Description,
        helpLinkUri: $"https://github.com/rjmurillo/moq.analyzers/blob/{ThisAssembly.GitCommitId}/docs/rules/{DiagnosticIds.SetupOnlyUsedForOverridableMembers}.md");

    /// <inheritdoc />
    public override ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics { get; } = ImmutableArray.Create(Rule);

    private protected override void RegisterCompilationActions(CompilationStartAnalysisContext context, MoqKnownSymbols knownSymbols)
    {
        context.RegisterOperationAction(
            operationAnalysisContext => AnalyzeInvocation(operationAnalysisContext, knownSymbols),
            OperationKind.Invocation);
    }

    private static void AnalyzeInvocation(OperationAnalysisContext context, MoqKnownSymbols knownSymbols)
    {
        if (context.Operation is not IInvocationOperation invocationOperation)
        {
            return;
        }

        IMethodSymbol targetMethod = invocationOperation.TargetMethod;
        if ((!targetMethod.IsMoqSetupMethod(knownSymbols) && !targetMethod.IsMoqEventSetupMethod(knownSymbols))
            || !MoqVerificationHelpers.TryGetNonOverridableMockedMember(invocationOperation, knownSymbols, out ISymbol? mockedMemberSymbol))
        {
            return;
        }

        Diagnostic diagnostic = invocationOperation.Syntax.CreateDiagnostic(Rule, mockedMemberSymbol.ToDisplayString());
        context.ReportDiagnostic(diagnostic);
    }
}