Added kNearestNeighbour and refactored Vector to a package level above and added a constructor

test/machine_learning/VectorTest.java

@@ -0,0 +1,91 @@
+package machine_learning;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class VectorTest
+{
+
+    @Test
+    void shouldInitializeZeroVector()
+    {
+        var v = new Vector(3);
+
+        var expected = new Vector(0d, 0d, 0d);
+
+        assertEquals(3, v.dimension());
+        assertEquals(expected, v);
+    }
+
+    @Test
+    void shouldReturnCorrectVectorWhenAdding()
+    {
+        var v1 = new Vector(1d, 2d);
+        var v2 = new Vector(3d, 4d);
+
+        var result = v1.add(v2);
+        var expected = new Vector(4d, 6d);
+
+        assertEquals(expected, result);
+    }
+
+    @Test
+    void shouldReturnCorrectVectorWhenSubtracting()
+    {
+        var v1 = new Vector(1d, 2d);
+        var v2 = new Vector(3d, 4d);
+
+        var result = v1.subtract(v2);
+        var expected = new Vector(-2d, -2d);
+
+        assertEquals(expected, result);
+    }
+
+    @Test
+    void shouldReturnCorrectVectorWhenScalarMultiplying()
+    {
+        var v1 = new Vector(1d, 2d);
+        var v2 = new Vector(3d, 4d);
+
+        var result = v1.scalar(v2);
+        var expected = 11d;
+
+        assertEquals(expected, result);
+    }
+
+    @Test
+    void shouldReturnCorrectVectorWhenEuclid()
+    {
+        var v1 = new Vector(1d, 2d);
+
+        var result = v1.euclid();
+        var expected = Math.sqrt(5);
+
+        assertEquals(expected, result);
+    }
+
+    @Test
+    void shouldReturnCorrectDistance()
+    {
+        var v1 = new Vector(1d, 2d);
+        var v2 = new Vector(3d, 4d);
+
+        var result = v1.distance(v2);
+        var expected = Math.sqrt(8);
+
+        assertEquals(expected, result);
+    }
+
+    @Test
+    void shouldReturnCorrectVectorWhenDividing()
+    {
+        var v1 = new Vector(1d, 2d);
+        var div = 2d;
+
+        var result = v1.divide(div);
+        var expected = new Vector(0.5d, 1d);
+
+        assertEquals(expected, result);
+    }
+}