Fix simple generator execution for parameterized methods

[Copilot]

Simple-pattern generator methods with parameters were failing at generation time with TargetParameterCountException (MSGH004). The runtime invocation path only handled zero args or a single converted arg, which broke methods like SimpleMethodWithParameter_Generator(int).

• Runtime invocation: robust parameter binding

  • Updated GeneratesMethodExecutionRuntime.ConvertArguments(...) to bind all method parameters instead of only the first.
  • Added strict over-arity handling (args.Length > parameters.Length).
  • For missing/null inputs, now supplies CLR default values per parameter type (e.g. 0 for int, null for reference/nullable types), allowing simple-pattern generators with parameters to execute.

• Regression coverage in generator runtime tests

  • Added a focused test in GeneratesMethodExecutionRuntimeTests to assert simple generator methods with parameters execute successfully using defaulted inputs.

• Issue test expectation alignment

  • Corrected SimpleMethodWithParameter generated-code expectation to match the actual partial signature (int return type + int someIntParameter) rather than a parameterless/string signature.

private static object?[]? ConvertArguments(object?[]? args, MethodInfo methodInfo)
{
    ParameterInfo[] parameters = methodInfo.GetParameters();
    if (parameters.Length == 0) return null;
    if (args != null && args.Length > parameters.Length) throw new TargetParameterCountException();

    object?[] convertedArguments = new object?[parameters.Length];
    for (int parameterIndex = 0; parameterIndex < parameters.Length; parameterIndex++)
    {
        ParameterInfo parameter = parameters[parameterIndex];
        object? argument = args != null && parameterIndex < args.Length ? args[parameterIndex] : null;
        if (argument == null)
        {
            convertedArguments[parameterIndex] = GetDefaultValue(parameter.ParameterType);
            continue;
        }

        Type targetType = Nullable.GetUnderlyingType(parameter.ParameterType) ?? parameter.ParameterType;
        convertedArguments[parameterIndex] = Convert.ChangeType(argument, targetType);
    }

    return convertedArguments;
}

Original prompt

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This section details on the original issue you should resolve

<issue_title>Simple methods with parameters generator fails</issue_title>
<issue_description>Take a look at the SimpleMethodWithParameterTests. It does not compile - the generators fails. But it shouln't. Fix it.

MSGH004: Failed to execute generator method 'SimpleMethodWithParameter_Generator': Error executing generator method 'SimpleMethodWithParameter_Generator': System.Reflection.TargetParameterCountException: Parameter count mismatch.
at System.Reflection.MethodBaseInvoker.ThrowTargetParameterCountException()
at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
at EasySourceGenerators.Generators.GeneratesMethodExecutionRuntime.ExecuteGeneratorMethodWithArgs(IMethodSymbol generatorMethod, IReadOnlyList`1 allPartialMethods, Compilation compilation, Object[] args)</issue_description>

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

• Fixes Simple methods with parameters generator fails #79

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[codecov]

Codecov Report

❌ Patch coverage is 75.00000% with 6 lines in your changes missing coverage. Please review.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
...tors.Generators/GeneratesMethodExecutionRuntime.cs	75.00%	4 Missing and 2 partials ⚠️

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