test: unit test for helper function

expected behavior is to return an ordered list of the unique values

tests/pytest/core/test_context_processors.py

@@ -0,0 +1,9 @@
+from benefits.core.context_processors import unique_values
+
+
+def test_unique_values():
+    original_list = ["a", "b", "c", "a", "a", "zzz", "b", "c", "d", "b"]
+
+    new_list = unique_values(original_list)
+
+    assert new_list == ["a", "b", "c", "zzz", "d"]