diff --git a/r_bindings/causalgraphs/tests/testthat/test.R b/r_bindings/causalgraphs/tests/testthat/test.R
index 749c454..b2fe214 100644
--- a/r_bindings/causalgraphs/tests/testthat/test.R
+++ b/r_bindings/causalgraphs/tests/testthat/test.R
@@ -6,9 +6,102 @@ test_that("basic DAG operations", {
   dag$add_node("A", FALSE)
   dag$add_node("B", FALSE)
   dag$add_edge("A", "B", 20)
+
   expect_setequal(dag$nodes(), c("A", "B"))
-  expect_equal(dag$node_count(), 2)
-  expect_equal(dag$edge_count(), 1)
+  expect_equal(dag$node_count(), 2L)
+  expect_equal(dag$edge_count(), 1L)
+
   expect_equal(dag$get_parents("B"), "A")
   expect_equal(dag$get_children("A"), "B")
-})
\ No newline at end of file
+
+  e <- dag$edges()
+  expect_true(is.list(e) && all(c("from", "to") %in% names(e)))
+  expect_equal(length(e$from), 1L)
+  expect_equal(paste0(e$from, "->", e$to), "A->B")
+})
+
+test_that("add_nodes_from with and without latent mask", {
+  # With latent mask
+  dag1 <- RDAG$new()
+  dag1$add_nodes_from(c("X", "Y", "Z"), c(TRUE, FALSE, TRUE))
+  expect_setequal(dag1$nodes(), c("X", "Y", "Z"))
+  expect_setequal(dag1$latents(), c("X", "Z"))
+
+  # Without latent mask (all observed). Pass NULL explicitly.
+  dag2 <- RDAG$new()
+  dag2$add_nodes_from(c("A", "B", "C"), NULL)
+  expect_setequal(dag2$nodes(), c("A", "B", "C"))
+  expect_length(dag2$latents(), 0L)
+})
+
+test_that("add_node defaults latent=FALSE and duplicate adds are no-ops", {
+  dag <- RDAG$new()
+  dag$add_node("L", FALSE)
+  dag$add_node("L", TRUE)
+  expect_setequal(dag$nodes(), "L")
+  expect_length(dag$latents(), 0L)
+  expect_equal(dag$node_count(), 1L)
+})
+
+test_that("add_edge auto-adds missing nodes; optional weight works", {
+  dag <- RDAG$new()
+
+  dag$add_edge("S", "T", NULL)
+  expect_setequal(dag$nodes(), c("S", "T"))
+  expect_equal(dag$node_count(), 2L)
+  expect_equal(dag$edge_count(), 1L)
+  expect_equal(dag$get_parents("T"), "S")
+  expect_equal(dag$get_children("S"), "T")
+
+  # another edge with an explicit weight
+  dag$add_edge("T", "U", 0.5)
+  expect_equal(dag$edge_count(), 2L)
+
+  # edge list is order-insensitive for assertions
+  e <- dag$edges()
+  got <- paste0(e$from, "->", e$to)
+  expect_setequal(got, c("S->T", "T->U"))
+})
+
+test_that("get_parents / get_children errors on unknown node", {
+  dag <- RDAG$new()
+  dag$add_nodes_from(c("A","B"), NULL)
+  dag$add_edge("A","B", NULL)
+
+  expect_error(dag$get_parents("Z"))
+  expect_error(dag$get_children("Z"))
+})
+
+test_that("get_ancestors_of returns nodes plus all their ancestors", {
+  dag <- RDAG$new()
+  dag$add_nodes_from(c("A","B","C","D"), NULL)
+  dag$add_edge("A","B", NULL)
+  dag$add_edge("B","C", NULL)
+  dag$add_edge("D","C", NULL)
+
+  # ancestors(C) = {A, B, D, C}  (includes the node itself per implementation)
+  anc_C <- dag$get_ancestors_of(c("C"))
+  expect_setequal(anc_C, c("A","B","C","D"))
+
+  # ancestors(B, D) = {A, B, D}
+  anc_BD <- dag$get_ancestors_of(c("B","D"))
+  expect_setequal(anc_BD, c("A","B","D"))
+
+  # Unknown node should error
+  expect_error(dag$get_ancestors_of(c("C","Z")))
+})
+
+test_that("nodes(), edges(), node_count(), edge_count(), latents() remain consistent", {
+  dag <- RDAG$new()
+  dag$add_nodes_from(c("L1","O1","O2"), c(TRUE, FALSE, FALSE))
+  dag$add_edge("O1","O2", NULL)
+  dag$add_edge("L1","O2", NULL)
+
+  expect_equal(dag$node_count(), 3L)
+  expect_equal(dag$edge_count(), 2L)
+  expect_setequal(dag$latents(), "L1")
+  expect_setequal(dag$nodes(), c("L1","O1","O2"))
+
+  e <- dag$edges()
+  expect_setequal(paste0(e$from, "->", e$to), c("O1->O2","L1->O2"))
+})