diff --git a/tests/testthat/test-api.R b/tests/testthat/test-api.R
new file mode 100644
index 0000000..c6b3738
--- /dev/null
+++ b/tests/testthat/test-api.R
@@ -0,0 +1,52 @@
+context("api")
+
+test_that("hex api covered",{
+
+  str_pal <- "viridis"
+  mat_pal <- colourvalues::get_palette("viridis")
+  int_mat_pal <- matrix( as.integer( mat_pal ), ncol = 4, byrow = TRUE )
+  nv_mat_pal <- matrix( as.numeric( as.integer( mat_pal ) ), ncol = 4, byrow = T )
+  unk_pal <- list()
+
+  iv <- 1L:5L
+  nv <- c(1.1,2.2,3.3,4.4,5.5)
+  sv <- letters[1:5]
+  lst <- list(1:5)
+  fv <- as.factor( iv )
+  lv <- c(FALSE, TRUE)
+
+  alpha = 1L
+
+  ## Teting numeric and int palettes reutrn same results
+  res1 <- colourvalues:::rcpp_colour_values_hex(
+    x = iv, palette = int_mat_pal, alpha = 255.0
+  )
+  res2 <- colourvalues:::rcpp_colour_values_hex(
+    x = iv, palette = nv_mat_pal, alpha = 255.0
+  )
+  expect_equal( res1, res2 )
+
+  expect_error(
+    colourvalues:::rcpp_colour_values_hex(
+      x = iv, palette = unk_pal, alpha = 255.0
+    )
+    , "colourvalues - Unknown palette type"
+  )
+
+  res_lst <- colourvalues:::rcpp_colour_values_hex(
+    x = lst, palette = mat_pal, alpha = 255.0
+  )
+
+  res_iv <- colourvalues:::rcpp_colour_values_hex(
+    x = iv, palette = mat_pal, alpha = 255.0
+  )
+
+  res_lv <- colourvalues:::rcpp_colour_values_hex(
+    x = lv, palette = mat_pal, alpha = 255.0
+  )
+
+  expect_equal( res_lst[[1]], res_iv )
+  expect_equal( res_lv, colourvalues::colour_values(1:2) )
+
+
+})