tower / files / test / rock-hull.test.ts

rock-hull.test.ts

1	import { describe, expect, it } from 'vitest'
2	import { ROCK_COVER, ROCK_MIN_KM, rockCover, rockShell } from '../src/views/rock-hull.js'
3
4	describe('the rock shell (D-076)', () => {
5	const h = rockShell()
6
7	it('never sinks into the metal skin', () => {
8	for (let i = 0; i < 4000; i++) {
9	const v = h((i * 2.399963) % (2 * Math.PI), (i * 0.1357) % 542 - 1)
10	expect(v).toBeGreaterThanOrEqual(ROCK_MIN_KM)
11	}
12	})
13
14	it('is one surface across the seam at theta = 0', () => {
15	for (const z of [3, 120, 333, 539]) expect(h(1e-9, z)).toBeCloseTo(h(2 * Math.PI - 1e-9, z), 5)
16	})
17
18	it('has relief worth the name: kilometres, not metres', () => {
19	const vals = Array.from({ length: 2000 }, (_, i) => h((i * 0.61) % (2 * Math.PI), (i * 0.27) % 540))
20	expect(Math.max(...vals) - Math.min(...vals)).toBeGreaterThan(3)
21	})
22
23	it('is the same rock on every load', () => {
24	expect(rockShell()(1, 100)).toBe(h(1, 100))
25	})
26	})
27
28	describe('the rock laid over the plant (D-081)', () => {
29	const cover = rockCover()
30	const samples = Array.from({ length: 4000 }, (_, i) => cover((i * 2.399963) % (2 * Math.PI), (i * 0.1357) % 540))
31
32	it('covers most of the hull and leaves some bare', () => {
33	const covered = samples.filter((c) => c >= ROCK_COVER).length / samples.length
34	expect(covered).toBeGreaterThan(0.5)
35	expect(covered).toBeLessThan(0.75)
36	})
37
38	it('is one field across the seam at theta = 0', () => {
39	for (const z of [3, 120, 333, 539]) expect(cover(1e-9, z)).toBeCloseTo(cover(2 * Math.PI - 1e-9, z), 5)
40	})
41
42	it('is dug clear round a clearing', () => {
43	const dug = rockCover([{ theta: 1, z: 200, r: 14 }])
44	for (let a = 0; a < 2 * Math.PI; a += 0.3) {
45	const d = 13 * Math.random()
46	expect(dug(1 + (d * Math.cos(a)) / 51, 200 + d * Math.sin(a))).toBe(0)
47	}
48	})
49	})