chore: add utility unit test

spec/utils_spec.lua

@@ -0,0 +1,19 @@
+local utils = require("utils")
+
+describe("findInArray", function()
+	it("should return the index of the found element", function()
+		local array = { { key = "hello" }, { key = "world" } }
+		local predicate = function(element)
+			return element.key == "world"
+		end
+		assert.are.same(2, utils.findInArray(array, predicate))
+	end)
+
+	it("should return nil if the element is not found", function()
+		local array = { { key = "hello" }, { key = "world" } }
+		local predicate = function(element)
+			return element.key == "foo"
+		end
+		assert.are.same(nil, utils.findInArray(array, predicate))
+	end)
+end)