fix(isthmus): is_distinct_from tests to cover rewrite

Author: asuriy

isthmus/src/test/java/io/substrait/isthmus/ComparisonFunctionsTest.java

@@ -1,5 +1,8 @@
 package io.substrait.isthmus;
 
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import io.substrait.isthmus.sql.SubstraitCreateStatementParser;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.CsvSource;
@@ -38,13 +41,31 @@ void is_not_false() throws Exception {
   void is_distinct_from(String left, String right) throws Exception {
     String query = String.format("SELECT (%s IS DISTINCT FROM %s) FROM numbers", left, right);
     assertSqlSubstraitRelRoundTrip(query, CREATES);
+
+    // Assert logical rewrite exists
+    io.substrait.plan.Plan plan =
+        toSubstraitPlan(
+            query, SubstraitCreateStatementParser.processCreateStatementsToCatalog(CREATES));
+    String planString = plan.toString();
+    assertTrue(
+        planString.contains("and") && planString.contains("or") && planString.contains("equal"),
+        "Expected Substrait plan to contain logical rewrite for IS DISTINCT FROM");
   }
 
   @ParameterizedTest
   @ValueSource(strings = {"int_a", "int_b", "double_a", "double_b"})
   void is_distinct_from_null_vs_col(String column) throws Exception {
     String query = String.format("SELECT (NULL IS DISTINCT FROM %s) FROM numbers", column);
     assertSqlSubstraitRelRoundTrip(query, CREATES);
+
+    // Assert logical rewrite exists
+    io.substrait.plan.Plan plan =
+        toSubstraitPlan(
+            query, SubstraitCreateStatementParser.processCreateStatementsToCatalog(CREATES));
+    String planString = plan.toString();
+    assertTrue(
+        planString.contains("is_not_null"),
+        "Expected Substrait plan to contain logical rewrite for NULL IS DISTINCT FROM to IS NOT NULL");
   }
 
   @ParameterizedTest
@@ -71,7 +92,7 @@ void least(String args) throws Exception {
   })
   void greatest(String args) throws Exception {
     String join_args = String.join(", ", args);
-    String query = String.format("SELECT LEAST(%s) FROM numbers", join_args);
+    String query = String.format("SELECT GREATEST(%s) FROM numbers", join_args);
     assertSqlSubstraitRelRoundTrip(query, CREATES);
   }
 }