From c4c1c840f8761ea45a3d2dcc912a59d8ced78cb5 Mon Sep 17 00:00:00 2001
From: LalleSX
Date: Sat, 24 Oct 2026 04:35:56 +0200
Subject: init

---
 src/physics/electricField.test.ts | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)
 create mode 100644 src/physics/electricField.test.ts

(limited to 'src/physics/electricField.test.ts')

diff --git a/src/physics/electricField.test.ts b/src/physics/electricField.test.ts
new file mode 100644
index 0000000..2e01309
--- /dev/null
+++ b/src/physics/electricField.test.ts
@@ -0,0 +1,21 @@
+import { describe, expect, it } from 'vitest';
+import { electricField, COULOMB_CONSTANT } from './electricField';
+
+describe('Coulomb electric field', () => {
+  it('points away from a positive charge with inverse-square magnitude', () => {
+    const field = electricField({ x: 2, y: 0, z: 0 }, [{ x: 0, y: 0, z: 0, coulombs: 1e-9 }]);
+    expect(field.x).toBeCloseTo(COULOMB_CONSTANT * 1e-9 / 4);
+    expect(field.y).toBe(0);
+    expect(field.z).toBe(0);
+  });
+  it('superposes opposite charges in the same direction at the midpoint', () => {
+    const field = electricField({ x: 0, y: 0, z: 0 }, [
+      { x: -1, y: 0, z: 0, coulombs: 1e-9 },
+      { x: 1, y: 0, z: 0, coulombs: -1e-9 },
+    ]);
+    expect(field.x).toBeCloseTo(2 * COULOMB_CONSTANT * 1e-9);
+  });
+  it('omits singular samples within the visualization exclusion radius', () => {
+    expect(electricField({ x: 0, y: 0, z: 0 }, [{ x: 0, y: 0, z: 0, coulombs: 1e-9 }])).toEqual({ x: 0, y: 0, z: 0 });
+  });
+});
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