use approx::assert_relative_eq;

use feos::pcsaft::{PcSaft, PcSaftParameters};

use feos_core::parameter::{IdentifierOption, Parameter};

use feos_core::{EquationOfState, StateBuilder};

use ndarray::*;

use quantity::si::*;

use std::error::Error;

use std::sync::Arc;

#[test]

fn test_dln_phi_dp() -> Result<(), Box<dyn Error>> {

let params = PcSaftParameters::from_json(

vec!["propane", "butane"],

"tests/pcsaft/test_parameters.json",

None,

IdentifierOption::Name,

)?;

let saft = Arc::new(PcSaft::new(Arc::new(params)));

let t = 300.0 * KELVIN;

let p = BAR;

let h = 1e-1 * PASCAL;

let s = StateBuilder::new(&saft)

.temperature(t)

.pressure(p)

.molefracs(&arr1(&[0.5, 0.5]))

.vapor()

.build()?;

let sh = StateBuilder::new(&saft)

.temperature(t)

.pressure(p + h)

.molefracs(&arr1(&[0.5, 0.5]))

.vapor()

.build()?;

let ln_phi = s.ln_phi()[0];

let ln_phi_h = sh.ln_phi()[0];

let dln_phi_dp = s.dln_phi_dp().get(0);

let dln_phi_dp_h = (ln_phi_h - ln_phi) / h;

assert_relative_eq!(dln_phi_dp, dln_phi_dp_h, max_relative = 1e-6);

Ok(())

}

#[test]

fn test_virial_is_not_nan() -> Result<(), Box<dyn Error>> {

let params = PcSaftParameters::from_json(

vec!["water_np"],

"tests/pcsaft/test_parameters.json",

None,

IdentifierOption::Name,

)?;

let saft = Arc::new(PcSaft::new(Arc::new(params)));

let virial_b = saft.second_virial_coefficient(300.0 * KELVIN, None)?;

assert!(!virial_b.is_nan());

Ok(())

}