add tests for adding Vectors

test/test_vector.py

@@ -0,0 +1,12 @@
+import unittest
+
+from fancymath.vector import Vector
+
+
+class TestVector(unittest.TestCase):
+    def test_add_vector(self):
+        v1 = Vector(1, 2, 3)
+        v2 = Vector(-3, -2, -1)
+        v3 = v1 + v2
+        self.assertIsInstance(v3, Vector)
+        self.assertEqual(v3.x, v1.x + v2.x)