#150: Add tests for ICAT limit filters

test/icat/filters/test_limit_filter.py

@@ -0,0 +1,58 @@
+import pytest
+
+from datagateway_api.common.exceptions import FilterError
+from datagateway_api.common.filter_order_handler import FilterOrderHandler
+from datagateway_api.common.icat.filters import (
+    PythonICATLimitFilter,
+    PythonICATSkipFilter,
+)
+
+
+class TestICATLimitFilter:
+    @pytest.mark.parametrize(
+        "limit_value",
+        [
+            pytest.param(10, id="typical"),
+            pytest.param(0, id="low boundary"),
+            pytest.param(9999, id="high boundary"),
+        ],
+    )
+    def test_valid_limit_value(self, icat_query, limit_value):
+        test_filter = PythonICATLimitFilter(limit_value)
+        test_filter.apply_filter(icat_query)
+
+        assert icat_query.limit == (0, limit_value)
+
+    @pytest.mark.parametrize(
+        "limit_value",
+        [pytest.param(-50, id="extreme invalid"), pytest.param(-1, id="boundary")],
+    )
+    def test_invalid_limit_value(self, icat_query, limit_value):
+        test_filter = PythonICATLimitFilter(limit_value)
+
+        with pytest.raises(FilterError):
+            test_filter.apply_filter(icat_query)
+
+    @pytest.mark.parametrize(
+        "skip_value, limit_value",
+        [
+            pytest.param(10, 10, id="identical typical values"),
+            pytest.param(0, 0, id="identical low boundary values"),
+            pytest.param(15, 25, id="different typical values"),
+            pytest.param(0, 9999, id="different boundary values"),
+        ],
+    )
+    def test_limit_and_skip_merge_correctly(self, icat_query, skip_value, limit_value):
+        """
+        Skip and limit values are set together in Python ICAT, limit value should match
+        max entities allowed in one transaction in ICAT as defined in ICAT properties
+        """
+        skip_filter = PythonICATSkipFilter(skip_value)
+        limit_filter = PythonICATLimitFilter(limit_value)
+
+        filter_handler = FilterOrderHandler()
+        filter_handler.add_filters([skip_filter, limit_filter])
+        filter_handler.merge_python_icat_limit_skip_filters()
+        filter_handler.apply_filters(icat_query)
+
+        assert icat_query.limit == (skip_value, limit_value)