#include <stdio.h>
#include <math.h>
#include <stdlib.h>
#include <string.h>

#define maxn 1024*128

long first[maxn], v[maxn*2], next[maxn*2], sel[maxn], val[maxn], fii[maxn], n;

int cmpint(const void *a, const void *b) {
	return -( *(long *)a - * ( long *)b);
}

long rez (long a) {
	sel[a] = -1;
	val[a] = 0;
	long x = first[a];
	while(x) {
		if (sel[v[x]] == 0) {
			rez(v[x]);
		}
		x = next[x];
	}
	x = first[a];
	long t = 0;
	while(x) {
		if (sel[v[x]] == 1) {
			fii[++t] = val[v[x]];
		}
		x = next[x];
	}
	
	qsort(fii + 1, t, sizeof(fii[1]), cmpint);
	sel[a] = 1;
	for (long i = 1; i <= t; ++i) {
		if (fii[i] + i > val[a]) {
			val[a] = fii[i] + i;
		}
	}
	return val[a];
}


int main() {
	freopen("zvon.in","r",stdin);
	freopen("zvon.out","w",stdout);
	
	long nr_caz, a, b;
	scanf("%ld", &nr_caz);
	
	for (long ii = 1; ii <= nr_caz; ++ii) {
		scanf("%ld", &n);
		memset(first, 0, sizeof(first));
		memset(sel, 0, sizeof(first));
		for (long i = 1; i < n; ++i) {
			scanf("%ld %ld", &a, &b);
			v[i * 2 - 1] = a;
			v[i * 2] = b;
			next[i * 2] = first[a];
			next[i * 2 - 1] = first[b];
			first[a] = i * 2;
			first[b] = i * 2 - 1;
		}
		printf("%ld\n", rez(1));
	}
	return 0 ;
}