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: sr1_trustregion.rs
    path of file: ./repos/argmin/crates/argmin/src/solver/quasinewton
    
    the code of the file until where you have to start completion: // Copyright 2019-2024 argmin developers
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://apache.org/licenses/LICENSE-2.0> or the MIT license <LICENSE-MIT or
// http://opensource.org/licenses/MIT>, at your option. This file may not be
// copied, modified, or distributed except according to those terms.

use crate::core::{
    ArgminFloat, CostFunction, Error, Executor, Gradient, Hessian, IterState, OptimizationResult,
    Problem, Solver, TerminationReason, TerminationStatus, T
    
    fn test_init() {
        let subproblem = CauchyPoint::new();

        let param: Vec<f64> = vec![-1.0, 1.0];

        let mut sr1: SR1TrustRegion<_, f64> = SR1TrustRegion::new(subproblem);

        // Forgot to initialize the parameter vector
        let state: IterState<Vec<f64>, Vec<f64>, (), Vec<Vec<f64>>, (), f64> = IterState::new();
        let problem = TestProblem::new();
        let res = sr1.init(&mut Problem::new(problem), state);
        assert_error!(
            res,
            ArgminError,
            concat!(
                "Not initialized: \"`SR1TrustRegion` requires an initial parameter vector. Please ",
                "provide an initial guess via `Executor`s `configure` method.\""
            )
        );

        // All good.
        let state: IterState<Vec<f64>, Vec<f64>, (), Vec<Vec<f64>>, (), f64> =
            IterState::new().param(param.clone());
        let problem = TestProblem::new();
        let (mut state_out, kv) = sr1.init(&mut Problem::new(problem), state).unwrap();

        assert!(kv.is_none());

        let s_param = state_out.take_param().unwrap();

        for (s, p) in s_param.iter().zip(param.iter()) {
            assert_eq!(s.to_ne_bytes(), p.to_ne_bytes());
        }

        let s_grad = state_out.take_gradient().unwrap();

        for (s, p) in s_grad.iter().zip(param.iter()) {
            assert_eq!(s.to_ne_bytes(), p.to_ne_bytes());
        }

        assert_eq!(state_out.get_cost().to_ne_bytes(), 1.0f64.to_ne_bytes())
    }