first test

eslint.config.mjs

@@ -1,14 +1,24 @@
 // @ts-check
 
-import eslint from '@eslint/js';
-import tseslint from 'typescript-eslint';
+import eslint from '@eslint/js'
+import tseslint from 'typescript-eslint'
+import jest from 'eslint-plugin-jest'
 
 export default tseslint.config(
   eslint.configs.recommended,
   ...tseslint.configs.recommended,
+  {
+    files: ['test/**'],
+    ...jest.configs['flat/recommended']
+  },
   {
     ignores: [
       'lib/'
     ]
+  },
+  {
+    rules: {
+      'semi': ['error', 'never']
+    }
   }
-);
+)

jest.config.js

@@ -0,0 +1,8 @@
+/** @type {import('ts-jest').JestConfigWithTsJest} **/
+// eslint-disable-next-line no-undef
+module.exports = {
+  testEnvironment: "node",
+  transform: {
+    "^.+.tsx?$": ["ts-jest", {}],
+  },
+}

package.json

@@ -19,7 +19,7 @@
     "build-demo": "pnpm --prefix demo build",
     "deploy-demo": "pnpm build-demo && gh-pages -d demo/build",
     "lint": "eslint",
-    "test": "jest --passWithNoTests"
+    "test": "jest"
   },
   "keywords": [
     "body",
@@ -43,11 +43,14 @@
     "@eslint/js": "^9.9.0",
     "@rollup/plugin-typescript": "^11.1.6",
     "@types/eslint__js": "^8.42.3",
+    "@types/jest": "^29.5.12",
     "@types/node": "^22.5.0",
     "eslint": "^9.9.0",
+    "eslint-plugin-jest": "^28.8.0",
     "gh-pages": "^6.1.1",
     "jest": "^29.7.0",
     "rollup": "^4.21.0",
+    "ts-jest": "^29.2.4",
     "ts-node": "^10.9.2",
     "tslib": "^2.6.3",
     "typescript": "^5.5.4",

rollup.config.mjs

@@ -1,7 +1,7 @@
 import fs from 'fs'
 import typescript from '@rollup/plugin-typescript'
 
-const packageJson = JSON.parse(fs.readFileSync('./package.json'));
+const packageJson = JSON.parse(fs.readFileSync('./package.json'))
 
 export default {
   input: 'src/index.ts',

src/Body.spec.ts

@@ -0,0 +1,17 @@
+import Body from "./Body"
+import Vector from "./Vector"
+
+describe('Body', () => {
+  describe('moveBodyThroughTime', () => {
+    it('should move body through delta time', () => {
+      const body = new Body({
+        position: new Vector(0, 0, 0),
+        velocity: new Vector(1, 2, -3)
+      })
+
+      body.moveBodyThroughTime(1)
+
+      expect(body.velocity).toEqual(new Vector(1, 2, -3))
+    })
+  })
+})

src/Body.ts

@@ -1,4 +1,4 @@
-import Vector from './Vector';
+import Vector from './Vector'
 
 export default class Body {
   mass: number
@@ -37,7 +37,7 @@ export default class Body {
   }
 
   setExternalForces(externalForces: Vector[]) {
-    this.externalForces = externalForces;
+    this.externalForces = externalForces
 
     this.netExternalForce = this.externalForces.reduce((total, force) => {
       total.x += force.x
@@ -59,7 +59,7 @@ export default class Body {
     const deltaPosition = this.velocity.scaleBy(deltaTime)
     this.position = this.position.sum(deltaPosition)
     if (this.pastPositions.length >= this.tailLength) {
-      this.pastPositions.pop();
+      this.pastPositions.pop()
     }
     this.pastPositions.unshift(this.position)
   }