diff --git a/R/filter_by_species.R b/R/filter_by_species.R
index e26c25b..bdd06ef 100644
--- a/R/filter_by_species.R
+++ b/R/filter_by_species.R
@@ -16,7 +16,7 @@
 #' @examples
 #' ## ADD EXAMPLE ----
 
-filter_by_species <- function (data, species, rm_na = FALSE) {
+filter_by_species <- function(data, species, rm_na = FALSE) {
   
   ## Check data object ----
   
@@ -44,6 +44,11 @@ filter_by_species <- function (data, species, rm_na = FALSE) {
   }
 
 
+  if (all(!(species %in% unique(data$"taxa")))) {
+    stop("The species provided are absent from 'data'", call. = FALSE)
+  }
+  
+  
   ## Filter by species ----
   
   data <- data[data$"taxa" %in% species, ]
diff --git a/tests/testthat/test-filter_by_species.R b/tests/testthat/test-filter_by_species.R
new file mode 100644
index 0000000..b107e05
--- /dev/null
+++ b/tests/testthat/test-filter_by_species.R
@@ -0,0 +1,93 @@
+## Data for tests ----
+
+df_cpr  <- data.frame("data_type" = rep("CPR North", 5),
+                      "species"   = c("n_pachyderma", "n_pachyderma", 
+                                      "conglobatus", "g_rubescens", 
+                                      "g_rubescens"))
+
+df_net  <- data.frame("data_type"     = rep("Net", 5),
+                      "t_parkerae_VT" = c(1:5),
+                      "conglobatus"   = c(1:5),
+                      "g_rubescens"   = c(1:5))
+
+df <- data.frame("data_type" = rep("Net", 5),
+                 "taxa"      = c("n_pachyderma", "n_pachyderma", 
+                                 "conglobatus", "g_rubescens", 
+                                 "g_rubescens"),
+                 "counts"    = c(1:4, NA))
+
+df2 <- data.frame("data_type" = rep("Net", 5),
+                 "taxa"      = c("n_pachyderma", "n_pachyderma", 
+                                 "conglobatus", "g_rubescens", 
+                                 "g_rubescens"),
+                 "counts"    = c(1:3, NA, NA))
+
+
+## filter_by_species() ----
+
+test_that("Test filter_by_species() for error", {
+  
+  expect_error(filter_by_species(df_cpr),
+               "This function is not designed to work with 'CPR North' data",
+               fixed = TRUE)
+  
+  expect_error(filter_by_species(df_net),
+               paste0("This function requires data in long format. Please use ", 
+                      "the function 'reshape_data()'"),
+               fixed = TRUE)
+  
+  expect_error(filter_by_species(df),
+               "Argument 'species' is required",
+               fixed = TRUE)
+  
+  expect_error(filter_by_species(df, species = 1),
+               "Argument 'species' must be a character of length >= 1",
+               fixed = TRUE)
+  
+  expect_error(filter_by_species(df, species = "toto"),
+               "The species provided are absent from 'data'",
+               fixed = TRUE)
+  
+  expect_error(filter_by_species(df, species = c("toto", "titi")),
+               "The species provided are absent from 'data'",
+               fixed = TRUE)
+})
+
+test_that("Test filter_by_species() for success", {
+  
+  expect_silent(res <- filter_by_species(df, species = c("conglobatus")))
+  
+  expect_true(is.data.frame(res))
+  expect_equal(ncol(res), ncol(df))
+  expect_equal(nrow(res), 1L)
+  
+  expect_silent(res <- filter_by_species(df, species = c("conglobatus", 
+                                                         "g_rubescens")))
+  
+  expect_true(is.data.frame(res))
+  expect_equal(ncol(res), ncol(df))
+  expect_equal(nrow(res), 3L)
+  
+  expect_silent(res <- filter_by_species(df, species = c("conglobatus", 
+                                                         "g_rubescens"),
+                                         rm_na = TRUE))
+  
+  expect_true(is.data.frame(res))
+  expect_equal(ncol(res), ncol(df))
+  expect_equal(nrow(res), 2L)
+  
+  expect_silent(res <- filter_by_species(df2, species = "g_rubescens",
+                                         rm_na = TRUE))
+  
+  expect_true(is.data.frame(res))
+  expect_equal(ncol(res), ncol(df))
+  expect_equal(nrow(res), 0L)
+  
+  expect_silent(res <- filter_by_species(df, species = c("conglobatus", 
+                                                         "g_rubescens",
+                                                         "titi")))
+  
+  expect_true(is.data.frame(res))
+  expect_equal(ncol(res), ncol(df))
+  expect_equal(nrow(res), 3L)
+})