#include <bits/stdc++.h>

using i64 = long long;
using u64 = unsigned long long;
using u32 = unsigned;
#define pll pair<ll, ll>
#define pii pair<int, int>
#define vi vector<int>
#define fir(i, a, b) for (int i = a; i <= b; i++)
#define pqi priority_queue<int> // 优先队列

#define all(x) x.begin(), x.end()
#define pb push_back
#define mp make_pair
#define fi first
#define se second

// TODO: Dynamic ModInt

template <typename T>
constexpr T power(T a, u64 b)
{
    T res{1};
    for (; b != 0; b /= 2, a *= a)
    {
        if (b % 2 == 1)
        {
            res *= a;
        }
    }
    return res;
}

template <u32 P>
constexpr u32 mulMod(u32 a, u32 b)
{
    return 1ULL * a * b % P;
}

template <u64 P>
constexpr u64 mulMod(u64 a, u64 b)
{
    u64 res = a * b - u64(1.L * a * b / P - 0.5L) * P;
    res %= P;
    return res;
}

template <typename U, U P>
    requires std::unsigned_integral<U>
struct ModIntBase
{
public:
    constexpr ModIntBase() : x{0} {}

    template <typename T>
        requires std::integral<T>
    constexpr ModIntBase(T x_) : x{norm(x_ % T{P})}
    {
    }

    constexpr static U norm(U x)
    {
        if ((x >> (8 * sizeof(U) - 1) & 1) == 1)
        {
            x += P;
        }
        if (x >= P)
        {
            x -= P;
        }
        return x;
    }

    constexpr U val() const
    {
        return x;
    }

    constexpr ModIntBase operator-() const
    {
        ModIntBase res;
        res.x = norm(P - x);
        return res;
    }

    constexpr ModIntBase inv() const
    {
        return power(*this, P - 2);
    }

    constexpr ModIntBase &operator*=(const ModIntBase &rhs) &
    {
        x = mulMod<P>(x, rhs.val());
        return *this;
    }

    constexpr ModIntBase &operator+=(const ModIntBase &rhs) &
    {
        x = norm(x + rhs.x);
        return *this;
    }

    constexpr ModIntBase &operator-=(const ModIntBase &rhs) &
    {
        x = norm(x - rhs.x);
        return *this;
    }

    constexpr ModIntBase &operator/=(const ModIntBase &rhs) &
    {
        return *this *= rhs.inv();
    }

    friend constexpr ModIntBase operator*(ModIntBase lhs, const ModIntBase &rhs)
    {
        lhs *= rhs;
        return lhs;
    }

    friend constexpr ModIntBase operator+(ModIntBase lhs, const ModIntBase &rhs)
    {
        lhs += rhs;
        return lhs;
    }

    friend constexpr ModIntBase operator-(ModIntBase lhs, const ModIntBase &rhs)
    {
        lhs -= rhs;
        return lhs;
    }

    friend constexpr ModIntBase operator/(ModIntBase lhs, const ModIntBase &rhs)
    {
        lhs /= rhs;
        return lhs;
    }

    friend constexpr std::ostream &operator<<(std::ostream &os, const ModIntBase &a)
    {
        return os << a.val();
    }

    friend constexpr bool operator==(ModIntBase lhs, ModIntBase rhs)
    {
        return lhs.val() == rhs.val();
    }

    friend constexpr bool operator!=(ModIntBase lhs, ModIntBase rhs)
    {
        return lhs.val() != rhs.val();
    }

    friend constexpr bool operator<(ModIntBase lhs, ModIntBase rhs)
    {
        return lhs.val() < rhs.val();
    }

private:
    U x;
};

template <u32 P>
using ModInt = ModIntBase<u32, P>;

template <u64 P>
using ModInt64 = ModIntBase<u64, P>;

constexpr u32 P = 1000000007;
using Z = ModInt<P>;

void solve()
{
    int n;
    std::cin >> n;

    std::vector<int> h(n);
    for (int i = 0; i < n; i++)
    {
        std::cin >> h[i];
    }

    Z ans = (h[0] == 0 ? 1 : 0);
    for (int i = 1; i < n; i++)
    {
        if (h[i] < h[i - 1])
        {
            ans = 0;
            break;
        }

        if (h[i] == h[i - 1])
        {
            ans *= h[i] + 1 - i;
        }
        else
        {
            ans *= 2;
        }
    }

    if (h[n - 1] != n - 1)
    {
        ans = 0;
    }

    std::cout << ans << "\n";
}
signed main()
{
    std::ios::sync_with_stdio(false);
    std::cin.tie(0);

    int t;
    std::cin >> t;
    while (t--)
    {
        solve();
    }
    return 0;
}