diff --git a/R/repro_code_utils.R b/R/repro_code_utils.R
index 71176de..439447e 100644
--- a/R/repro_code_utils.R
+++ b/R/repro_code_utils.R
@@ -9,7 +9,7 @@ pair_seq <- function(idxs) {
     return(integer(0))
   }
   
-  if (identical(length(idxs) %% 2L, 0L)) {
+  if (!identical(length(idxs) %% 2L, 0L)) {
     stop("The lenght of idxs is not even number")
   }
   
diff --git a/tests/testthat/test-source_methods.R b/tests/testthat/test-source_methods.R
index e951f35..cad2497 100644
--- a/tests/testthat/test-source_methods.R
+++ b/tests/testthat/test-source_methods.R
@@ -245,3 +245,33 @@ test_that("Updating filter on source works fine", {
   expect_setequal(coh$get_data(1, state = "post")$iris$Species, "setosa")
 })
 
+test_that("Removing step with ID '0' triggers warning", {
+  iris_source <- set_source(
+    tblist(iris = iris)
+    ) %>% add_filter(
+      discrete_filter_species
+    )
+
+  expect_warning(iris_source$rm_step("0"), "No steps to remove or wrong ID passed")
+})
+
+test_that("Initialize source with primary key set attribute primary_key", {
+  key <- 1
+  iris_source <- set_source(
+    tblist(iris = iris),
+    primary_keys = key)
+
+  type_of_primary_key <- typeof(key)
+  expect_equal(iris_source$primary_keys, key)
+  expect_type(iris_source$primary_keys, type_of_primary_key)
+  expect_false(is.null(iris_source$primary_keys))
+})
+
+test_that("get returns attributes of source", {
+  iris_source <- set_source(
+    tblist(iris = iris),
+    atribute1 = "test")
+
+  expect_type(iris_source$get("atribute1"), "character")
+  expect_type(iris_source$get("atribute2"), "NULL")
+})