#150: Add tests for ICAT distinct filters

test/icat/filters/test_distinct_filter.py

@@ -0,0 +1,45 @@
+import pytest
+
+from datagateway_api.common.exceptions import FilterError
+from datagateway_api.common.icat.filters import PythonICATDistinctFieldFilter
+
+
+class TestICATDistinctFilter:
+    def test_valid_str_field_input(self, icat_query):
+        test_filter = PythonICATDistinctFieldFilter("name")
+        test_filter.apply_filter(icat_query)
+
+        assert (
+            icat_query.conditions == {"name": "!= null"}
+            and icat_query.aggregate == "DISTINCT"
+        )
+
+    def test_valid_list_fields_input(self, icat_query):
+        test_filter = PythonICATDistinctFieldFilter(["doi", "name", "title"])
+        test_filter.apply_filter(icat_query)
+
+        assert (
+            icat_query.conditions
+            == {"doi": "!= null", "name": "!= null", "title": "!= null"}
+            and icat_query.aggregate == "DISTINCT"
+        )
+
+    def test_invalid_field(self, icat_query):
+        test_filter = PythonICATDistinctFieldFilter("my_new_field")
+        with pytest.raises(FilterError):
+            test_filter.apply_filter(icat_query)
+
+    def test_distinct_aggregate_added(self, icat_query):
+        test_filter = PythonICATDistinctFieldFilter("id")
+        test_filter.apply_filter(icat_query)
+
+        assert icat_query.aggregate == "DISTINCT"
+
+    @pytest.mark.parametrize("existing_aggregate", ["COUNT", "AVG", "SUM"])
+    def test_existing_aggregate_appended(self, icat_query, existing_aggregate):
+        icat_query.setAggregate(existing_aggregate)
+
+        test_filter = PythonICATDistinctFieldFilter("name")
+        test_filter.apply_filter(icat_query)
+
+        assert icat_query.aggregate == f"{existing_aggregate}:DISTINCT"