package httpdl

import "testing"

// TestBelowSpeed covers the speedGuard decision, including the counter-reset
// case (item [1]): d.completed can jump backward when singleOnce rewrites it
// with an absolute StoreInt64 and a resumed Range is answered by a 200 that
// resets the offset to 0. A backward jump must NOT be read as a slow window, or
// a healthy download would be false-aborted.
func TestBelowSpeed(t *testing.T) {
	const limit = 1000
	cases := []struct {
		name      string
		prev, now int64
		want      bool
	}{
		{"fast", 0, 5000, false},
		{"exactly at limit aborts", 1000, 2000, true},
		{"just under limit aborts", 1000, 1999, true},
		{"just over limit ok", 1000, 2001, false},
		{"stalled aborts", 4242, 4242, true},
		{"counter reset is not slow", 1_000_000, 0, false},
		{"small backward jump is not slow", 5000, 4500, false},
	}
	for _, c := range cases {
		t.Run(c.name, func(t *testing.T) {
			if got := belowSpeed(c.prev, c.now, limit); got != c.want {
				t.Errorf("belowSpeed(%d, %d, %d) = %v; want %v", c.prev, c.now, limit, got, c.want)
			}
		})
	}
}