diff --git a/DESCRIPTION b/DESCRIPTION
index 32cd511..7090b75 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -22,5 +22,6 @@ Suggests: knitr,
     rmarkdown,
     dplyr,
     shiny,
-    manipulateWidget
+    manipulateWidget,
+    testthat
 VignetteBuilder: knitr
diff --git a/R/add_flows.R b/R/add_flows.R
index cf99253..8ac74c8 100644
--- a/R/add_flows.R
+++ b/R/add_flows.R
@@ -53,7 +53,7 @@ addFlows <- function(map, lng0, lat0, lng1, lat1, color = "blue", flow = 1,
   if (is.null(time)) time <- 1
   if (is.null(layerId)) layerId <- sprintf("_flow (%s,%s) -> (%s,%s)", lng0, lat0, lng1, lat1)
 
-  options <- .makeOptions(
+  options <- .preprocessArgs(
     required = list(lng0 = lng0, lat0 = lat0, lng1 = lng1, lat1 = lat1, layerId = layerId, time = time),
     optional = list(dir = dir, color = color, value = flow, maxValue = maxFlow,
                     minThickness = minThickness, maxThickness = maxThickness,
@@ -84,7 +84,7 @@ updateFlows <- function(map, layerId, color = NULL, flow = NULL, opacity = NULL,
                         minThickness = 1, maxThickness = 20) {
   if (is.null(time)) time <- 1
 
-  options <- .makeOptions(
+  options <- .preprocessArgs(
     required = list(layerId = layerId, time = time),
     optional = list(dir = dir, color = color, value = flow, maxValue = maxFlow,
                     minThickness = minThickness, maxThickness = maxThickness,
diff --git a/R/add_minicharts.R b/R/add_minicharts.R
index bc5443a..a5743c5 100644
--- a/R/add_minicharts.R
+++ b/R/add_minicharts.R
@@ -146,7 +146,7 @@ addMinicharts <- function(map, lng, lat, chartdata = 1, time = NULL, maxValues =
     labels <- "none"
   }
 
-  options <- .makeOptions(
+  options <- .preprocessArgs(
     required = list(lng = lng, lat = lat, layerId = layerId, time = time),
     optional = list(type = type, width = width, height = height,
                     opacity = opacity, labels = labels,
@@ -208,7 +208,7 @@ updateMinicharts <- function(map, layerId, chartdata = NULL, time = NULL, maxVal
     }
   }
 
-  options <- .makeOptions(
+  options <- .preprocessArgs(
     required = list(layerId = layerId, time = time),
     optional = list(type = type, width = width, height = height,
                     opacity = opacity, labels = labels,
diff --git a/R/make_options.R b/R/preprocess_args.R
similarity index 53%
rename from R/make_options.R
rename to R/preprocess_args.R
index d448dc6..4afa781 100644
--- a/R/make_options.R
+++ b/R/preprocess_args.R
@@ -1,6 +1,9 @@
 # Copyright © 2016 RTE Réseau de transport d’électricité
 
-#' Private function that prepare R arguments to be sent to javascript functions.
+#' Private function that prepare arguments for other functions. It transforms
+#' them in a table with one column per argument. In order to improve memory
+#' management, optional arguments with a single value are not added to the table
+#' but there value is stored in a specific list.
 #'
 #' @param required
 #'   Named list of required parameters
@@ -8,11 +11,13 @@
 #'   Named list of optional parameters
 #'
 #' @return
-#'   A data.frame where each column represent one parameter
+#'   A list with two elements:
+#'   - options: data.frame with required args and variing optional args
+#'   - staticOptions: a list with single value args.
 #'
 #' @noRd
 #'
-.makeOptions <- function(required, optional) {
+.preprocessArgs <- function(required, optional) {
   options <- do.call(data.frame, required)
   staticOptions <- list()
   for (o in names(optional)) {
diff --git a/tests/testthat.R b/tests/testthat.R
new file mode 100644
index 0000000..acc36c6
--- /dev/null
+++ b/tests/testthat.R
@@ -0,0 +1,4 @@
+library(testthat)
+library(leaflet.minicharts)
+
+test_check("leaflet.minicharts")
diff --git a/tests/testthat/test-preprocess_args.R b/tests/testthat/test-preprocess_args.R
new file mode 100644
index 0000000..3280e37
--- /dev/null
+++ b/tests/testthat/test-preprocess_args.R
@@ -0,0 +1,40 @@
+context(".preprocessArgs")
+
+describe(".preprocessArgs", {
+  it ("creates a data.frame with one column per argument", {
+    opts <- .preprocessArgs(list(a = 1:3, b = 4:6), list(c = 7:9, d = 10:12))
+    expect_is(opts$options, "data.frame")
+    expect_equal(dim(opts$options), c(3, 4))
+    expect_equal(names(opts$options), c("a", "b", "c", "d"))
+  })
+
+  it ("separates static optional arguments", {
+    opts <- .preprocessArgs(list(a = 1:3, b = 4:6), list(c = 7:9, d = 10))
+    expect_is(opts$options, "data.frame")
+    expect_equal(dim(opts$options), c(3, 3))
+    expect_equal(names(opts$options), c("a", "b", "c"))
+    expect_is(opts$staticOptions, "list")
+    expect_equal(names(opts$staticOptions), "d")
+  })
+
+  it ("does not separate static required arguments", {
+    opts <- .preprocessArgs(list(a = 1:3, b = 4), list(c = 7:9, d = 10:12))
+    expect_is(opts$options, "data.frame")
+    expect_equal(dim(opts$options), c(3, 4))
+    expect_equal(names(opts$options), c("a", "b", "c", "d"))
+    expect_equal(length(opts$staticOptions), 0)
+  })
+
+  it ("does not accept NULL required arguments", {
+    expect_error(.preprocessArgs(list(a = 1:3, b = NULL), list(c = 7:9, d = 10:12)))
+  })
+
+  it ("accepts NULL optional required", {
+    opts <- .preprocessArgs(list(a = 1:3, b = 4:6), list(c = 7:9, d = NULL))
+    expect_is(opts$options, "data.frame")
+    expect_equal(dim(opts$options), c(3, 3))
+    expect_equal(names(opts$options), c("a", "b", "c"))
+    expect_equal(length(opts$staticOptions), 0)
+  })
+
+})