test: clear datetime between searches

Author: sbrunato

Diff for: tests/api/test_search.py

@@ -85,6 +85,10 @@ def test_temporal_search_two_tailed():
     assert search.start_date is None
     assert search.end_date == utcnow
 
+    search = Search(collections=["collection1"])
+    assert search.start_date is None
+    assert search.end_date is None
+
 
 def test_temporal_search_open():
     # Test open date range