diff --git a/tests/test-transform_data.R b/tests/test-transform_data.R
new file mode 100644
index 000000000..a970d8652
--- /dev/null
+++ b/tests/test-transform_data.R
@@ -0,0 +1,39 @@
+test_that(
+  "epidist_transform_data with default settings returns data unchanged",
+  {
+    family <- epidist_family(prep_obs, family = lognormal())
+    formula <- epidist_formula(prep_obs, family = family, formula = bf(mu ~ 1))
+
+    transformed <- epidist_transform_data(prep_obs, family, formula)
+    expect_identical(transformed, prep_obs)
+  }
+)
+
+test_that("epidist_transform_data errors when passed incorrect inputs", {
+  family <- epidist_family(prep_obs, family = lognormal())
+  formula <- epidist_formula(prep_obs, family = family, formula = bf(mu ~ 1))
+
+  expect_error(epidist_transform_data(list(), family, formula))
+})
+
+test_that("epidist_transform_data_model.default returns data unchanged", {
+  family <- epidist_family(prep_obs, family = lognormal())
+  formula <- epidist_formula(prep_obs, family = family, formula = bf(mu ~ 1))
+
+  transformed <- epidist_transform_data_model(prep_obs, family, formula)
+  expect_identical(transformed, prep_obs)
+})
+
+test_that("epidist_transform_data works with different model types", {
+  family <- epidist_family(prep_obs, family = lognormal())
+  formula <- epidist_formula(prep_obs, family = family, formula = bf(mu ~ 1))
+
+  expect_identical(
+    epidist_transform_data(prep_naive_obs, family, formula),
+    prep_naive_obs
+  )
+  expect_identical(
+    epidist_transform_data(prep_obs_gamma, family, formula),
+    prep_obs_gamma
+  )
+})