diff --git a/tests/test_utils.py b/tests/test_utils.py
new file mode 100644
index 0000000..e77c0a5
--- /dev/null
+++ b/tests/test_utils.py
@@ -0,0 +1,24 @@
+import pytest
+
+
+from google_books.utils import fh_date
+
+
+@pytest.mark.parametrize(
+    "arg,expectation",
+    [
+        ("nyp_20231208_google.txt", "20231208"),
+        ("nyp_20240101_google_recap.txt", "20240101"),
+    ],
+)
+def test_report_name_base_valid(arg, expectation):
+    assert fh_date(arg) == expectation
+
+
+@pytest.mark.parametrize(
+    "arg",
+    ["foo", "20231208_google.txt", "nyp_foo_google.txt", "nyp-20231208-google.txt"],
+)
+def test_report_name_base_invalid(arg):
+    with pytest.raises(ValueError):
+        fh_date(arg)