Additional tests for PositionOf/LastPositionOf based on CQL clarification https://jira.hl7.org/browse/FHIR-52042

Author: Bryn Rhodes

tests/cql/CqlStringOperatorsTest.xml

@@ -138,6 +138,11 @@
 			<expression>LastPositionOf('hi', 'Say hi to Ohio!')</expression>
 			<output>11</output>
 		</test>
+		<test name="LastPositionOf3" version="1.0">
+			<capability code="string-operators" />
+			<expression>LastPositionOf('', 'Say hi to Ohio!')</expression>
+			<output>15</output>
+		</test>
 	</group>
 	<group name="Length" version="1.0">
 		<capability code="string-operators" />
@@ -266,6 +271,11 @@
 			<expression>PositionOf('c', 'ab')</expression>
 			<output>-1</output>
 		</test>
+		<test name="PositionOf3" version="1.0">
+			<capability code="string-operators" />
+			<expression>PositionOf('', 'Say hi to Ohio!')</expression>
+			<output>0</output>
+		</test>
 	</group>
 	<group name="ReplaceMatches" version="1.0">
 		<capability code="string-operators" />