diff --git a/DESCRIPTION b/DESCRIPTION
index 6061899..cecb01c 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -13,9 +13,12 @@ Encoding: UTF-8
 LazyData: true
 RoxygenNote: 7.2.3
 Depends: 
-    R (>= 2.10)
+    R (>= 4.1.0)
 URL: https://eodagmbh.github.io/r-maplibregl/
 Imports: 
     geojsonsf,
     htmlwidgets,
     purrr
+Suggests: 
+    testthat (>= 3.0.0)
+Config/testthat/edition: 3
diff --git a/R/layer.R b/R/layer.R
index b5a8fb0..df8a1d6 100644
--- a/R/layer.R
+++ b/R/layer.R
@@ -8,16 +8,15 @@
 #'
 #' @export
 Layer <- function(type, id, source = NULL, paint = NULL, layout = NULL, ...) {
-  lay <- list(
+  list(
     type = type,
     id = id,
     source = source,
     paint = paint,
     layout = layout
   ) |>
-    purrr::compact()
-  class(lay) <- "MapLibreLayer"
-  return(lay)
+    purrr::compact() |>
+    set_maplibre_class("MapLibreLayer")
 }
 
 
diff --git a/R/marker.R b/R/marker.R
index 12c44f5..ee3a88a 100644
--- a/R/marker.R
+++ b/R/marker.R
@@ -4,30 +4,27 @@
 #' @param popup
 #' @export
 #' @example examples/markers.R
-Marker <- function(lngLat, popup , ...) {
-  mark <- list(
-    lngLat  = lngLat,
+Marker <- function(lngLat, popup = NULL, ...) {
+  list(
+    lngLat = lngLat,
     popup = popup,
     options = MarkerOptions(...)
   ) |>
-    purrr::compact()
-  class(mark) <- "MapLibreMarker"
-  return(mark)
+    purrr::compact() |>
+    set_maplibre_class("MapLibreMarker")
 }
 
-#' Title
-#'
-#' @param ...
-#'
-#' @return
-#' @export
-#'
-#' @examples
-MarkerOptions <- function(...){
+MarkerOptions <- function(...) {
   marker_options <- list(...)
-  stopifnot(sapply(marker_options[c("anchor", "color", "pitchAlignment", "rotationAlignment")], function(x){is.null(x) | is.character(x)}))
-  stopifnot(sapply(marker_options["draggable"], function(x) {is.null(x) | is.logical(x)}))
-  stopifnot(sapply(marker_options[c("rotation", "scale")], function(x) {is.null(x) | is.numeric(x)}))
+  stopifnot(sapply(marker_options[c("anchor", "color", "pitchAlignment", "rotationAlignment")], function(x) {
+    is.null(x) | is.character(x)
+  }))
+  stopifnot(sapply(marker_options["draggable"], function(x) {
+    is.null(x) | is.logical(x)
+  }))
+  stopifnot(sapply(marker_options[c("rotation", "scale")], function(x) {
+    is.null(x) | is.numeric(x)
+  }))
   marker_options <- marker_options |>
     purrr::compact()
   class(marker_options) <- "MarkerOptions"
diff --git a/R/utils.R b/R/utils.R
new file mode 100644
index 0000000..e5a170f
--- /dev/null
+++ b/R/utils.R
@@ -0,0 +1,4 @@
+set_maplibre_class <- function(.obj, class_name) {
+  class(.obj) <- c(class(.obj), class_name)
+  return(.obj)
+}
diff --git a/data-raw/basemaps.R b/data-raw/basemaps.R
index 69dd3ad..0da0cd6 100644
--- a/data-raw/basemaps.R
+++ b/data-raw/basemaps.R
@@ -3,10 +3,10 @@ PROVIDERS <- list(
     url = "https://basemaps.cartocdn.com/gl/%s-gl-style/style.json",
     themes = c("dark-matter", "voyager", "positron")
   )
-  #, mapbox = list(
+  # , mapbox = list(
   #  url = "mapbox://styles/mapbox/%s",
   #  themes = c("streets-v11", "outdoors-v11", "light-v10", "dark-v10", "satellite-v9", "satellite-steets-v11")
-  #)
+  # )
 )
 
 build_urls <- function(provider) {
diff --git a/tests/testthat.R b/tests/testthat.R
new file mode 100644
index 0000000..e29e8d3
--- /dev/null
+++ b/tests/testthat.R
@@ -0,0 +1,12 @@
+# This file is part of the standard setup for testthat.
+# It is recommended that you do not modify it.
+#
+# Where should you do additional test configuration?
+# Learn more about the roles of various files in:
+# * https://r-pkgs.org/testing-design.html#sec-tests-files-overview
+# * https://testthat.r-lib.org/articles/special-files.html
+
+library(testthat)
+library(maplibre)
+
+test_check("maplibre")
diff --git a/tests/testthat/test-layer.R b/tests/testthat/test-layer.R
new file mode 100644
index 0000000..ba736e1
--- /dev/null
+++ b/tests/testthat/test-layer.R
@@ -0,0 +1,17 @@
+test_that("layer spec", {
+  # Prepare
+  id <- "test"
+  type <- "fill"
+
+  # Act
+  layer <- Layer(
+    id = id,
+    type = type
+  )
+
+  # Assert
+  expect_equal(layer$id, id)
+  expect_equal(layer$type, type)
+  expect_s3_class(layer, c("list"))
+  expect_s3_class(layer, c("MapLibreLayer"))
+})
diff --git a/tests/testthat/test-marker.R b/tests/testthat/test-marker.R
new file mode 100644
index 0000000..38bb360
--- /dev/null
+++ b/tests/testthat/test-marker.R
@@ -0,0 +1,12 @@
+test_that("marker spec", {
+  # Prepare
+  lng_lat <- c(5, 5)
+
+  # Act
+  marker <- Marker(lng_lat)
+
+  # Assert
+  expect_equal(marker$lngLat, lng_lat)
+  expect_s3_class(marker, "list")
+  expect_s3_class(marker, "MapLibreMarker")
+})