keplerian-core/dist/test/simulation.test.js

High-performance TypeScript library for orbital mechanics calculations, providing numerical integration, state propagation, and perturbation modeling for Keplerian orbits.

import { simulate } from '../src/simulation';
describe('Simulation Function', () => {
    // Test case for basic simulation with RK4 integrator
    it('should simulate a basic orbit using RK4 integrator', () => {
        const initialConditions = {
            position: { x: 149.6e9, y: 0 }, // 1 AU
            velocity: { x: 0, y: 29780 } // Earth's orbital velocity around Sun
        };
        const simulationParams = {
            gravitationalConstant: 6.67430e-11,
            centralMass: 1.989e30, // Sun's mass
            orbitingMass: 5.972e24, // Earth's mass
            gravitationalParameter: 6.67430e-11 * 1.989e30, // G * M_sun
            timeStep: 3600, // 1 hour
            totalTime: 24 * 3600, // 1 Earth day
            integrator: 'rk4' // Using RK4 for better accuracy
        };
        const result = simulate(initialConditions, simulationParams, 'json');
        expect(result).toBeInstanceOf(Array);
        const states = result;
        expect(states.length).toBeGreaterThan(0);
        expect(states[0].position).toEqual(initialConditions.position);
    });
    // Test case for different integrator (Euler)
    it('should simulate an orbit using Euler integrator', () => {
        const initialConditions = {
            position: { x: 149.6e9, y: 0 },
            velocity: { x: 0, y: 29780 }
        };
        const simulationParams = {
            gravitationalConstant: 6.67430e-11,
            centralMass: 1.989e30,
            orbitingMass: 5.972e24,
            gravitationalParameter: 6.67430e-11 * 1.989e30,
            timeStep: 3600,
            totalTime: 24 * 3600,
            integrator: 'euler' // Using Euler integrator
        };
        const result = simulate(initialConditions, simulationParams, 'json');
        expect(result).toBeInstanceOf(Array);
        const states = result;
        expect(states.length).toBeGreaterThan(0);
    });
    // Test case for CSV format output
    it('should return CSV format when requested', () => {
        const initialConditions = {
            position: { x: 149.6e9, y: 0 },
            velocity: { x: 0, y: 29780 }
        };
        const simulationParams = {
            gravitationalConstant: 6.67430e-11,
            centralMass: 1.989e30,
            orbitingMass: 5.972e24,
            gravitationalParameter: 6.67430e-11 * 1.989e30,
            timeStep: 3600,
            totalTime: 24 * 3600,
            integrator: 'rk4'
        };
        const result = simulate(initialConditions, simulationParams, 'csv');
        expect(typeof result).toBe('string');
        expect(result).toContain('position.x,position.y,velocity.x,velocity.y');
    });
    // Test case for unknown integrator
    it('should throw an error for an unknown integrator', () => {
        const initialConditions = {
            position: { x: 0, y: 0 },
            velocity: { x: 0, y: 0 }
        };
        const simulationParams = {
            gravitationalConstant: 6.67430e-11,
            centralMass: 1.989e30,
            orbitingMass: 1,
            gravitationalParameter: 6.67430e-11 * 1.989e30,
            timeStep: 1,
            totalTime: 1,
            integrator: 'unknown' // Cast to any to test unknown case
        };
        expect(() => simulate(initialConditions, simulationParams, 'json')).toThrow('Unknown integrator: unknown');
    });
    // Test case for Leapfrog integrator
    it('should simulate an orbit using Leapfrog integrator', () => {
        const initialConditions = {
            position: { x: 149.6e9, y: 0 },
            velocity: { x: 0, y: 29780 }
        };
        const simulationParams = {
            gravitationalConstant: 6.67430e-11,
            centralMass: 1.989e30,
            orbitingMass: 5.972e24,
            gravitationalParameter: 6.67430e-11 * 1.989e30,
            timeStep: 3600,
            totalTime: 24 * 3600,
            integrator: 'leapfrog' // Using Leapfrog integrator
        };
        const result = simulate(initialConditions, simulationParams, 'json');
        expect(result).toBeInstanceOf(Array);
        const states = result;
        expect(states.length).toBeGreaterThan(0);
    });
    // Test case for RK2 integrator
    it('should simulate an orbit using RK2 integrator', () => {
        const initialConditions = {
            position: { x: 149.6e9, y: 0 },
            velocity: { x: 0, y: 29780 }
        };
        const simulationParams = {
            gravitationalConstant: 6.67430e-11,
            centralMass: 1.989e30,
            orbitingMass: 5.972e24,
            gravitationalParameter: 6.67430e-11 * 1.989e30,
            timeStep: 3600,
            totalTime: 24 * 3600,
            integrator: 'rk2' // Using RK2 integrator
        };
        const result = simulate(initialConditions, simulationParams, 'json');
        expect(result).toBeInstanceOf(Array);
        const states = result;
        expect(states.length).toBeGreaterThan(0);
    });
    // Test case for Velocity Verlet integrator
    it('should simulate an orbit using Velocity Verlet integrator', () => {
        const initialConditions = {
            position: { x: 149.6e9, y: 0 },
            velocity: { x: 0, y: 29780 }
        };
        const simulationParams = {
            gravitationalConstant: 6.67430e-11,
            centralMass: 1.989e30,
            orbitingMass: 5.972e24,
            gravitationalParameter: 6.67430e-11 * 1.989e30,
            timeStep: 3600,
            totalTime: 24 * 3600,
            integrator: 'velocity-verlet' // Using Velocity Verlet integrator
        };
        const result = simulate(initialConditions, simulationParams, 'json');
        expect(result).toBeInstanceOf(Array);
        const states = result;
        expect(states.length).toBeGreaterThan(0);
    });
});