test: Add tests for vector & fix: Precise loss of unit vector creation

src/simulator/vector.ts

@@ -38,13 +38,21 @@ export class Vector implements IVector {
     }
 
     public static createUnitVector(angle: number): Vector {
-        return new Vector(Math.cos(angle), Math.sin(angle));
+        const fixedAngle = parseFloat(angle.toFixed(3));
+
+        return new Vector(Math.round(Math.cos(fixedAngle)), Math.round(Math.sin(fixedAngle)));
     }
 }
 
 export class VectorCollection extends LinkedNodes<Vector> {
-    public constructor() {
+    public constructor(iterable?: Iterable<Vector>) {
         super();
+
+        if(iterable) {
+            for(const item of iterable) {
+                this.push(item);
+            }
+        }
     }
 
     public getSum(): Vector {

src/test/vector.test.ts

@@ -0,0 +1,64 @@
+import { Vector, VectorCollection } from "@/simulator/vector";
+
+describe("vector-tests", () => {
+    it("zero-vector", () => {
+        const zero = Vector.Zero;
+
+        expect(zero.x).toBe(0);
+        expect(zero.y).toBe(0);
+        expect(zero.length).toBe(0);
+    });
+
+    it("vector-length", () => {
+        const vector = new Vector(3, 4);
+
+        expect(vector.length).toBe(5);
+    });
+
+    it("vector-addition", () => {
+        const vector1 = new Vector(3, 4);
+        const vector2 = new Vector(5, 6);
+
+        expect(Vector.add(vector1, vector2)).toEqual(new Vector(8, 10));
+    });
+
+    it("vector-subtraction", () => {
+        const vector1 = new Vector(3, 4);
+        const vector2 = new Vector(5, 6);
+
+        expect(Vector.sub(vector1, vector2)).toEqual(new Vector(-2, -2));
+    });
+
+    it("vector-multiplication", () => {
+        const vector1 = new Vector(3, 4);
+        const vector2 = new Vector(5, 6);
+
+        // 3 * 5 + 4 * 6 = 39
+        expect(Vector.multiply(vector1, vector2)).toBe(39);
+    });
+
+    it("vector-multiply-scalar", () => {
+        const vector = new Vector(3, 4);
+
+        expect(Vector.multiplyScalar(vector, 100)).toEqual(new Vector(300, 400));
+    });
+
+    it("vector-create-unit-vector", () => {
+        const vector = Vector.createUnitVector(Math.PI / 2);
+
+        expect(vector).toEqual(new Vector(-0, 1));
+    });
+});
+
+describe("vector-collection-tests", () => {
+    const vectors = new VectorCollection([
+        new Vector(3, 4),
+        new Vector(5, 6),
+        new Vector(7, 8),
+        new Vector(9, 10),
+    ]);
+
+    it("sum-of-vectors", () => {
+        expect(vectors.getSum()).toEqual(new Vector(24, 28));
+    });
+});