tests: replace DATEOF with toTimestamp on cassandra >=4.1

Cassandra after 4.1 dropped DATEOF in favor of toTimestamp.
Test needs to be adopted.

Author: dkropachev

cassandra_test.go

@@ -602,15 +602,25 @@ func TestCAS(t *testing.T) {
 	}
 
 	insertBatch := session.Batch(LoggedBatch)
-	insertBatch.Query("INSERT INTO cas_table (title, revid, last_modified) VALUES ('_foo', 2c3af400-73a4-11e5-9381-29463d90c3f0, DATEOF(NOW()))")
-	insertBatch.Query("INSERT INTO cas_table (title, revid, last_modified) VALUES ('_foo', 3e4ad2f1-73a4-11e5-9381-29463d90c3f0, DATEOF(NOW()))")
+	if *flagDistribution == "cassandra" && flagCassVersion.AtLeast(4, 1, 0) {
+		insertBatch.Query("INSERT INTO cas_table (title, revid, last_modified) VALUES ('_foo', 2c3af400-73a4-11e5-9381-29463d90c3f0, toTimestamp(NOW()))")
+		insertBatch.Query("INSERT INTO cas_table (title, revid, last_modified) VALUES ('_foo', 3e4ad2f1-73a4-11e5-9381-29463d90c3f0, toTimestamp(NOW()))")
+	} else {
+		insertBatch.Query("INSERT INTO cas_table (title, revid, last_modified) VALUES ('_foo', 2c3af400-73a4-11e5-9381-29463d90c3f0, DATEOF(NOW()))")
+		insertBatch.Query("INSERT INTO cas_table (title, revid, last_modified) VALUES ('_foo', 3e4ad2f1-73a4-11e5-9381-29463d90c3f0, DATEOF(NOW()))")
+	}
 	if err := session.ExecuteBatch(insertBatch); err != nil {
 		t.Fatal("insert:", err)
 	}
 
 	failBatch = session.Batch(LoggedBatch)
-	failBatch.Query("UPDATE cas_table SET last_modified = DATEOF(NOW()) WHERE title='_foo' AND revid=2c3af400-73a4-11e5-9381-29463d90c3f0 IF last_modified=DATEOF(NOW());")
-	failBatch.Query("UPDATE cas_table SET last_modified = DATEOF(NOW()) WHERE title='_foo' AND revid=3e4ad2f1-73a4-11e5-9381-29463d90c3f0 IF last_modified=DATEOF(NOW());")
+	if *flagDistribution == "cassandra" && flagCassVersion.AtLeast(4, 1, 0) {
+		failBatch.Query("UPDATE cas_table SET last_modified = toTimestamp(NOW()) WHERE title='_foo' AND revid=2c3af400-73a4-11e5-9381-29463d90c3f0 IF last_modified=toTimestamp(NOW());")
+		failBatch.Query("UPDATE cas_table SET last_modified = toTimestamp(NOW()) WHERE title='_foo' AND revid=3e4ad2f1-73a4-11e5-9381-29463d90c3f0 IF last_modified=toTimestamp(NOW());")
+	} else {
+		failBatch.Query("UPDATE cas_table SET last_modified = DATEOF(NOW()) WHERE title='_foo' AND revid=2c3af400-73a4-11e5-9381-29463d90c3f0 IF last_modified=DATEOF(NOW());")
+		failBatch.Query("UPDATE cas_table SET last_modified = DATEOF(NOW()) WHERE title='_foo' AND revid=3e4ad2f1-73a4-11e5-9381-29463d90c3f0 IF last_modified=DATEOF(NOW());")
+	}
 	if applied, iter, err := session.ExecuteBatchCAS(failBatch, &titleCAS, &revidCAS, &modifiedCAS); err != nil {
 		t.Fatal("insert:", err)
 	} else if applied {