You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: small_world_rand.rs
    path of file: ./repos/freenet-core/crates/core/src/topology
    
    the code of the file until where you have to start completion: #[cfg(test)]
pub(super) mod test_utils {
    use rand::Rng;

    use crate::ring::Distance;

    // Function to generate a random link distance based on Kleinberg's d^{-1} distribution
    pub(in crate::topology) fn random_l
    
    fn chi_squared_test() {
        let d_min = 0.01;
        let d_max = 0.5;
        let n = 10000; // Number of samples
        let num_bins = 20; // Number of bins for histogram
        let mut bins = vec![0; num_bins];

        // Generate a bunch of link distances
        for _ in 0..n {
            let d = random_link_distance(Distance::new(d_min)).as_f64();
            let bin_index = ((d - d_min) / (d_max - d_min) * (num_bins as f64)).floor() as usize;
            if bin_index < num_bins {
                bins[bin_index] += 1;
            }
        }

        // Perform chi-squared test
        let expected_counts: Vec<_> = (0..num_bins)
            .map(|i| {
                let lower = d_min + (d_max - d_min) * (i as f64 / num_bins as f64);
                let upper = d_min + (d_max - d_min) * ((i as f64 + 1.0) / num_bins as f64);
                ((upper - lower) / (upper.powf(-1.0) - lower.powf(-1.0))).floor() * n as f64
                    / num_bins as f64
            })
            .collect();

        let chi_squared = expected_counts
            .iter()
            .zip(bins.iter())
            .map(|(&e, &o)| ((o as f64 - e) * (o as f64 - e)) / e)
            .sum::<f64>();

        // Degrees of freedom is num_bins - 1
        let dof = num_bins - 1;
        let chi = ChiSquared::new(dof as f64).unwrap();

        let p_value = 1.0 - chi.cdf(chi_squared);

        // Check if p_value is above 0.05, indicating that we fail to reject the null hypothesis
        assert!(
            p_value > 0.05,
            "Chi-squared test failed, p_value = {}",
            p_value
        );
    }