--- a
+++ b/tests/deseq2/test_interactions.py
@@ -0,0 +1,42 @@
+import unittest
+
+import numpy as np
+import patsy
+
+from inmoose.deseq2 import DESeq, makeExampleDESeqDataSet
+from inmoose.utils import Factor
+
+
+@unittest.skip("lfcShrink is not implemented")
+class Test(unittest.TestCase):
+    def test_interation_errors(self):
+        """test that interactions throw errors"""
+        dds = makeExampleDESeqDataSet(n=100, m=8)
+        dds.obs["group"] = Factor(np.repeat(["X", "Y"], dds.n_obs / 2))
+        dds.design = "~ condition + group + condition:group"
+        dds = DESeq(dds)
+        self.assertEqual(dds.resultsNames()[3], "conditionB.groupY")
+
+        # interactions error
+        with self.assertRaisesRegex(
+            ValueError, expected_regex="designs with interations"
+        ):
+            DESeq(dds, betaPrior=True)
+
+        # also lfcShrink
+        res = dds.results(name="conditionB.groupY")
+        with self.assertRaises(NotImplementedError):
+            res = lfcShrink(dds, coef=4, res=res, type="normal")  # noqa: F821
+
+        res = dds.results(contrast=["condition", "B", "A"])
+        with self.assertRaises(NotImplementedError):
+            res = lfcShrink(  # noqa: F821
+                dds, contrast=["condition", "B", "A"], res=res, type="normal"
+            )
+
+        # however, this is allowed
+        dds2 = dds.copy()
+        dds2.design = patsy.dmatrix("~ condition + group + condition:group", dds2.obs)
+        dds2 = DESeq(dds2)
+        dds2.results(name="conditionB.groupY")
+        lfcShrink(dds2, coef=4, res=res, type="normal")  # noqa: F821