Minor: Add tests for StringView / character functions

Author: alamb

datafusion/sqllogictest/test_files/string_view.slt

@@ -322,6 +322,23 @@ logical_plan
 03)----TableScan: test projection=[column1_utf8, column2_utf8, column1_utf8view]
 
 
+# Ensure string functions use native StringView implementation
+# and do not fall back to Utf8 or LargeUtf8
+# Should see no casts to Utf8 in the plans below
+
+query TT
+EXPLAIN SELECT
+  column1_utf8view like 'foo' as "like",
+  column1_utf8view ilike 'foo' as "ilike"
+FROM test;
+----
+logical_plan
+01)Projection: test.column1_utf8view LIKE Utf8View("foo") AS like, test.column1_utf8view ILIKE Utf8View("foo") AS ilike
+02)--TableScan: test projection=[column1_utf8view]
+
+
+
+
 statement ok
 drop table test;