Add serialization tests.

Author: chrisberkhout

x-pack/plugin/esql/src/test/java/org/elasticsearch/xpack/esql/expression/function/scalar/string/SpaceSerializationTests.java

@@ -0,0 +1,31 @@
+/*
+ * 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.expression.function.scalar.string;
+
+import org.elasticsearch.xpack.esql.core.expression.Expression;
+import org.elasticsearch.xpack.esql.core.tree.Source;
+import org.elasticsearch.xpack.esql.expression.AbstractExpressionSerializationTests;
+
+import java.io.IOException;
+
+public class SpaceSerializationTests extends AbstractExpressionSerializationTests<Space> {
+    @Override
+    protected Space createTestInstance() {
+        Source source = randomSource();
+        Expression number = randomChild();
+        return new Space(source, number);
+    }
+
+    @Override
+    protected Space mutateInstance(Space instance) throws IOException {
+        Source source = instance.source();
+        Expression number = instance.number();
+        number = randomValueOtherThan(number, AbstractExpressionSerializationTests::randomChild);
+        return new Space(source, number);
+    }
+}