Enforce MSGH007 for simple generators with parameters and finish SimpleMethodWithParameter test

[Copilot]

Simple [GeneratesMethod] generators are compile-time executors and must not accept runtime parameters, but this path was not validated and the existing test was unfinished. This PR completes the test and adds a dedicated validation path that emits MSGH007 on the generator method signature (not method body).

• Completed coverage for the unfinished scenario

  • Finalized SimpleMethodWithParameterTests_Test to assert:
    • MSGH007 is emitted.
    • Diagnostic location is in source.
    • Highlighted span includes method signature and excludes method body.

• Added simple-pattern parameter validation in generation pipeline

  • In GeneratesMethodGenerationPipeline, for non-switch and non-fluent groups:
    • detect generator methods with one or more parameters,
    • emit CannotUseRuntimeParameterForCompileTimeGeneratorError (MSGH007),
    • stop generation for that invalid group.

• Diagnostic location is now signature-scoped

  • Added signature span computation (method start -> end of parameter list) so errors target declaration signature rather than body content.

if (methodsWithParameters.Count > 0)
{
    foreach (GeneratesMethodGenerationTarget methodWithParameters in methodsWithParameters)
    {
        context.ReportDiagnostic(Diagnostic.Create(
            GeneratesMethodGeneratorDiagnostics.CannotUseRuntimeParameterForCompileTimeGeneratorError,
            GetMethodSignatureLocation(methodWithParameters.Syntax)));
    }

    return string.Empty;
}

Original prompt

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This section details on the original issue you should resolve

<issue_title>Continue working on SimpleMethodWithParameterTests_Test</issue_title>
<issue_description>1. Finish the test
2. Modify the generators so the test passes - generators should highlight the generator method signature (not body) and report analyzer error MSGH007</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Continue working on SimpleMethodWithParameterTests_Test #81

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ All tests successful. No failed tests found.

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[Copilot]

Pull request overview

This PR enforces that “simple pattern” [GeneratesMethod] generators (compile-time executors) cannot declare runtime parameters, and completes the previously unfinished test case to validate both the diagnostic (MSGH007) and its source location span.

Changes:

• Added a validation step in the simple-pattern generation path to emit MSGH007 when a generator method declares one or more parameters, and to skip generation for that invalid group.
• Implemented signature-scoped diagnostic location computation (start of method declaration through the end of the parameter list).
• Finished SimpleMethodWithParameterTests_Test to assert MSGH007 is emitted and that the highlighted span includes the signature but not the method body.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
EasySourceGenerators.Generators/GeneratesMethodGenerationPipeline.cs	Adds simple-pattern parameter validation and signature-scoped diagnostic locations for MSGH007.
EasySourceGenerators.GeneratorTests/SimpleMethodWithParameter.cs	Completes the test to verify MSGH007 emission and correct diagnostic span targeting.

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