Matching alias template as template argument

Consider the following code:

#include <type_traits>
#include <vector>

template<template<class...> class T, class... U>
struct is_specialization_of : std::false_type{};

template<template<class...> class T, class... U>
struct is_specialization_of<T, T<U...>> : std::true_type{};

template<class T, class U = int>
struct test{};

// (1) ok
static_assert(is_specialization_of<test, test<int>>::value);

template<class T>
using alias = test<T>;

// (2) fails
static_assert(is_specialization_of<alias, alias<int>>::value);

int main()
{
}

Why does (2), i.e. static_assert that uses alias template, fail?

How does the template argument deduction process in (2) differ from the one in (1)?