Add Lua unit tests to builtin using busted (#9184)

builtin/common/tests/vector_spec.lua

@@ -0,0 +1,46 @@
+_G.vector = {}
+dofile("builtin/common/vector.lua")
+
+describe("vector", function()
+	describe("new()", function()
+		it("constructs", function()
+			assert.same({ x = 0, y = 0, z = 0 }, vector.new())
+			assert.same({ x = 1, y = 2, z = 3 }, vector.new(1, 2, 3))
+			assert.same({ x = 3, y = 2, z = 1 }, vector.new({ x = 3, y = 2, z = 1 }))
+
+			local input = vector.new({ x = 3, y = 2, z = 1 })
+			local output = vector.new(input)
+			assert.same(input, output)
+			assert.are_not.equal(input, output)
+		end)
+
+		it("throws on invalid input", function()
+			assert.has.errors(function()
+				vector.new({ x = 3 })
+			end)
+
+			assert.has.errors(function()
+				vector.new({ d = 3 })
+			end)
+		end)
+	end)
+
+	it("equal()", function()
+			local function assertE(a, b)
+				assert.is_true(vector.equals(a, b))
+			end
+			local function assertNE(a, b)
+				assert.is_false(vector.equals(a, b))
+			end
+
+			assertE({x = 0, y = 0, z = 0}, {x = 0, y = 0, z = 0})
+			assertE({x = -1, y = 0, z = 1}, {x = -1, y = 0, z = 1})
+			local a = { x = 2, y = 4, z = -10 }
+			assertE(a, a)
+			assertNE({x = -1, y = 0, z = 1}, a)
+	end)
+
+	it("add()", function()
+		assert.same({ x = 2, y = 4, z = 6 }, vector.add(vector.new(1, 2, 3), { x = 1, y = 2, z = 3 }))
+	end)
+end)