for _, reg := range toRegister {
		registry.MustRegister(reg)
	}
	tro := vec.NewForLabelValuesSafe(0, 1, []string{"avalue"})
	exerciseTimingRatioHistogram(t, testHistogramName, t0, clk, registry, tro)
}

// exerciseTimingRatioHistogram does a rough behavioral test of a
// RatioedObserver.  A fake clock is used, and the exercise consists
// of repeatedly changing that fake clock by an amount of time chosen