diff --git a/unittests/test_json_schema_exporter.py b/unittests/test_json_schema_exporter.py
index 99ef153834b6ca558ddf29ca3dbde936421f764e..9fc597cd3c76c6fee2b533dda4e3160f24c649dc 100644
--- a/unittests/test_json_schema_exporter.py
+++ b/unittests/test_json_schema_exporter.py
@@ -279,6 +279,7 @@ def test_rt_with_references():
     rt.add_property(name="RefProp", datatype=db.REFERENCE)
 
     schema = rtjs(rt)
+    props = schema["properties"]
 
     rt = db.RecordType()
     rt.add_property(name="RefProp", datatype="OtherType")
@@ -295,6 +296,18 @@ def test_rt_with_references():
 
     schema = rtjs(rt)
 
+    rt = db.RecordType()
+    rt.add_property(name="FileProp", datatype=db.FILE)
+
+    with raises(NotImplementedError):
+        schema = rtjs(rt)
+
+    rt = db.RecordType()
+    rt.add_property(name="FileProp", datatype=db.LIST(db.FILE))
+
+    with raises(NotImplementedError):
+        schema = rtjs(rt)
+
 
 def test_broken():