#include<bits/stdc++.h>

using namespace std;

const int maxi=1e6+2;
int h[maxi];
void solve()
{
    int n,k;

    cin>>n;
    cin>>k;

    for (int i=1;i<=n;i++)
        cin>>h[i];
    int ans=0;
    ans+=(h[1]-1)/k;

    for (int i=2;i<=n;i++)
        ans+=(h[i]-h[i-1]-1)/k;

    cout<<ans<<endl;

    return;
}
int main()
{
    int t;
    cin>>t;

    while(t--)
        solve();

    return 0;
}