public static void AddTestExpr(this MetadataContext cx, Expression expr, params ParameterExpression[] parameters)
{
var typeCount = cx.DefinedTypes.Count;
var name = typeCount < 15 ? ((char)('C' + typeCount)).ToString() : "C" + typeCount;
var ns = ((TypeOrNamespace.NamespaceSignatureCase)cx.DefinedTypes.FirstOrDefault()?.Signature.Parent)?.Item ??
new NamespaceSignature("NS", NamespaceSignature.Global);
var type = TypeSignature.Class(name, ns, Accessibility.APublic);
var method = new MethodSignature(type, parameters.Select(p => new MethodParameter(p.Type, p.Name)).ToImmutableArray(), "M", expr.Type(), true, Accessibility.APublic, false, false, false, false, ImmutableArray <GenericParameter> .Empty);
var methodDef = new MethodDef(method, parameters.ToImmutableArray(), expr);
var typeDef = TypeDef.Empty(type).With(members: ImmutableArray.Create <MemberDef>(methodDef));
cx.AddType(typeDef);
cx.CommitWaitingTypes();
}