ES|QL: add generator for SAMPLE command (#135334)

x-pack/plugin/esql/qa/testFixtures/src/main/java/org/elasticsearch/xpack/esql/generator/EsqlQueryGenerator.java

@@ -21,6 +21,7 @@ import org.elasticsearch.xpack.esql.generator.command.pipe.LimitGenerator;
 import org.elasticsearch.xpack.esql.generator.command.pipe.LookupJoinGenerator;
 import org.elasticsearch.xpack.esql.generator.command.pipe.MvExpandGenerator;
 import org.elasticsearch.xpack.esql.generator.command.pipe.RenameGenerator;
+import org.elasticsearch.xpack.esql.generator.command.pipe.SampleGenerator;
 import org.elasticsearch.xpack.esql.generator.command.pipe.SortGenerator;
 import org.elasticsearch.xpack.esql.generator.command.pipe.StatsGenerator;
 import org.elasticsearch.xpack.esql.generator.command.pipe.TimeSeriesStatsGenerator;
@@ -71,6 +72,7 @@ public class EsqlQueryGenerator {
         LookupJoinGenerator.INSTANCE,
         MvExpandGenerator.INSTANCE,
         RenameGenerator.INSTANCE,
+        SampleGenerator.INSTANCE,
         SortGenerator.INSTANCE,
         StatsGenerator.INSTANCE,
         WhereGenerator.INSTANCE

x-pack/plugin/esql/qa/testFixtures/src/main/java/org/elasticsearch/xpack/esql/generator/command/pipe/SampleGenerator.java

@@ -0,0 +1,47 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0; you may not use this file except in compliance with the Elastic License
+ * 2.0.
+ */
+
+package org.elasticsearch.xpack.esql.generator.command.pipe;
+
+import org.elasticsearch.xpack.esql.generator.Column;
+import org.elasticsearch.xpack.esql.generator.QueryExecutor;
+import org.elasticsearch.xpack.esql.generator.command.CommandGenerator;
+
+import java.util.List;
+import java.util.Map;
+
+import static org.elasticsearch.test.ESTestCase.randomDoubleBetween;
+
+public class SampleGenerator implements CommandGenerator {
+
+    public static final String SAMPLE = "sample";
+    public static final CommandGenerator INSTANCE = new SampleGenerator();
+
+    @Override
+    public CommandDescription generate(
+        List<CommandDescription> previousCommands,
+        List<Column> previousOutput,
+        QuerySchema schema,
+        QueryExecutor executor
+    ) {
+        double n = randomDoubleBetween(0.0, 1.0, false);
+        String cmd = " | SAMPLE " + n;
+        return new CommandDescription(SAMPLE, this, cmd, Map.of());
+    }
+
+    @Override
+    public ValidationResult validateOutput(
+        List<CommandDescription> previousCommands,
+        CommandDescription commandDescription,
+        List<Column> previousColumns,
+        List<List<Object>> previousOutput,
+        List<Column> columns,
+        List<List<Object>> output
+    ) {
+        return CommandGenerator.expectSameColumns(previousColumns, columns);
+    }
+}