diff --git a/tests/testthat/test-add_n.tbl_survfit.R b/tests/testthat/test-add_n.tbl_survfit.R
new file mode 100644
index 000000000..890886087
--- /dev/null
+++ b/tests/testthat/test-add_n.tbl_survfit.R
@@ -0,0 +1,35 @@
+test_that("add_n.tbl_survfit() works", {
+  # add_n.tbl_survfit works
+  fit1 <- survival::survfit(survival::Surv(ttdeath, death) ~ 1, trial)
+  fit2 <- survival::survfit(survival::Surv(ttdeath, death) ~ grade, trial)
+
+  expect_silent(
+    res1 <- list(fit1, fit2) |>
+      tbl_survfit(times = c(12, 24)) |>
+      add_n()
+  )
+  expect_equal(
+    as.data.frame(res1, col_label = FALSE)$N,
+    c("200", "200", NA, NA, NA)
+  )
+
+
+  # add_n.tbl_survfit does not accept additional arguments
+  expect_error(
+    res2 <- list(fit1, fit2) |>
+      tbl_survfit(times = c(12, 24)) |>
+      add_n(statistic = "{N_nonmiss} / {N_obs}"),
+    regexp = "`...` must be empty"
+  )
+
+  # mess with the call object, trigger `safe_survfit_eval` function
+  trial2 <- NA
+  fit1$call$data <- trial2
+
+  expect_error(
+    res3 <- list(fit1, fit2) |>
+      tbl_survfit(times = c(12, 24)) |>
+      add_n(),
+    regexp = "error may be a due to the construction of the original"
+  )
+})
diff --git a/tests/testthat/test-add_nevent.tbl_survfit.R b/tests/testthat/test-add_nevent.tbl_survfit.R
new file mode 100644
index 000000000..78d5aa5a8
--- /dev/null
+++ b/tests/testthat/test-add_nevent.tbl_survfit.R
@@ -0,0 +1,48 @@
+test_that("add_n.tbl_survfit() works", {
+  tbl <- trial |>
+    tbl_survfit(
+      include = trt,
+      y = "Surv(ttdeath, death)",
+      times = 12
+    )
+
+  # total N events added to table is accurate
+  expect_silent(
+    res <- tbl |> add_nevent()
+  )
+
+  expect_equal(
+    as.data.frame(res, col_label = FALSE)$nevent,
+    c("112", NA, NA)
+  )
+
+  # stacked fits work
+  fit1 <- survival::survfit(survival::Surv(ttdeath, death) ~ 1, trial)
+  fit2 <- survival::survfit(survival::Surv(ttdeath, death) ~ trt, trial)
+
+  expect_silent(
+    res1 <- list(fit1, fit2) |>
+      tbl_survfit(times = c(12, 24)) |>
+      add_nevent()
+  )
+  expect_equal(
+    as.data.frame(res1, col_label = FALSE)$nevent,
+    c("112", "112", NA, NA)
+  )
+
+
+  # add_nevent.tbl_survfit does not accept additional arguments (yet)
+  expect_error(
+    res2 <- tbl |> add_nevent(location = "level"),
+    regexp = "`...` must be empty"
+  )
+
+  # mess with the tbl_survfit object to trigger error
+  res3 <- list(fit1, fit2) |>
+    tbl_survfit(times = c(12, 24))
+  class(res3$inputs$x[[1]]) <- NULL
+  expect_error(
+    res3 |> add_nevent(),
+    regexp = "objects must have class"
+  )
+})
diff --git a/tests/testthat/test-add_p.tbl_survfit.R b/tests/testthat/test-add_p.tbl_survfit.R
new file mode 100644
index 000000000..d2f76aec9
--- /dev/null
+++ b/tests/testthat/test-add_p.tbl_survfit.R
@@ -0,0 +1,14 @@
+test_that("add_p.tbl_survfit() works", {
+  tbl <- trial |>
+    tbl_survfit(
+      include = trt,
+      y = "Surv(ttdeath, death)",
+      times = 12
+    )
+
+  # total N added to table is accurate
+  expect_error(
+    res <- tbl |> add_p(),
+    NA
+  )
+})