[KQL] Fix node builder with empty array (#155901)

## Summary

Fixes #95657.

Updates the logic for `nodeBuilder` when passing an empty array to
`nodeBuilder.and`/`nodeBuilder.or` to actually return a `KueryNode`
instead of `undefined`.

### Checklist

- [ ]
[Documentation](https://www.elastic.co/guide/en/kibana/master/development-documentation.html)
was added for features that require explanation or tutorials
- [x] [Unit or functional
tests](https://www.elastic.co/guide/en/kibana/master/development-tests.html)
were updated or added to match the most common scenarios

packages/kbn-es-query/src/kuery/node_types/node_builder.test.ts

@@ -55,6 +55,25 @@ describe('nodeBuilder', () => {
  });
 
  describe('and method', () => {
+ test('no clauses', () => {
+ const node = nodeBuilder.and([]);
+ const query = toElasticsearchQuery(node);
+ expect(node).toMatchInlineSnapshot(`
+ Object {
+ "arguments": Array [],
+ "function": "and",
+ "type": "function",
+ }
+ `);
+ expect(query).toMatchInlineSnapshot(`
+ Object {
+ "bool": Object {
+ "filter": Array [],
+ },
+ }
+ `);
+ });
+
  test('single clause', () => {
  const nodes = [nodeBuilder.is('foo', 'bar')];
  const query = toElasticsearchQuery(nodeBuilder.and(nodes));
@@ -166,6 +185,26 @@ describe('nodeBuilder', () => {
  });
 
  describe('or method', () => {
+ test('no clauses', () => {
+ const node = nodeBuilder.or([]);
+ const query = toElasticsearchQuery(node);
+ expect(node).toMatchInlineSnapshot(`
+ Object {
+ "arguments": Array [],
+ "function": "or",
+ "type": "function",
+ }
+ `);
+ expect(query).toMatchInlineSnapshot(`
+ Object {
+ "bool": Object {
+ "minimum_should_match": 1,
+ "should": Array [],
+ },
+ }
+ `);
+ });
+
  test('single clause', () => {
  const nodes = [nodeBuilder.is('foo', 'bar')];
  const query = toElasticsearchQuery(nodeBuilder.or(nodes));

packages/kbn-es-query/src/kuery/node_types/node_builder.ts

@@ -10,23 +10,23 @@ import type { RangeFilterParams } from '../../filters';
 import { KueryNode, nodeTypes } from '../types';
 
 export const nodeBuilder = {
- is: (fieldName: string, value: string | KueryNode) => {
+ is: (fieldName: string, value: string | KueryNode): KueryNode => {
  return nodeTypes.function.buildNodeWithArgumentNodes('is', [
  nodeTypes.literal.buildNode(fieldName),
  typeof value === 'string' ? nodeTypes.literal.buildNode(value) : value,
  ]);
  },
  or: (nodes: KueryNode[]): KueryNode => {
- return nodes.length > 1 ? nodeTypes.function.buildNode('or', nodes) : nodes[0];
+ return nodes.length === 1 ? nodes[0] : nodeTypes.function.buildNode('or', nodes);
  },
  and: (nodes: KueryNode[]): KueryNode => {
- return nodes.length > 1 ? nodeTypes.function.buildNode('and', nodes) : nodes[0];
+ return nodes.length === 1 ? nodes[0] : nodeTypes.function.buildNode('and', nodes);
  },
  range: (
  fieldName: string,
  operator: keyof Pick<RangeFilterParams, 'gt' | 'gte' | 'lt' | 'lte'>,
  value: number | string
- ) => {
+ ): KueryNode => {
  return nodeTypes.function.buildNodeWithArgumentNodes('range', [
  nodeTypes.literal.buildNode(fieldName),
  operator,

src/plugins/data/server/search/session/session_service.test.ts

@@ -575,7 +575,11 @@ describe('SearchSessionService', () => {
  const [[findOptions]] = savedObjectsClient.find.mock.calls;
  expect(findOptions).toMatchInlineSnapshot(`
  Object {
- "filter": undefined,
+ "filter": Object {
+ "arguments": Array [],
+ "function": "and",
+ "type": "function",
+ },
  "page": 0,
  "perPage": 5,
  "type": "search-session",

x-pack/plugins/alerting/server/lib/convert_rule_ids_to_kuery_node.test.ts

@@ -61,6 +61,10 @@ describe('convertRuleIdsToKueryNode', () => {
  });
 
  test('should convert empty ids array correctly', () => {
- expect(convertRuleIdsToKueryNode([])).toEqual(undefined);
+ expect(convertRuleIdsToKueryNode([])).toEqual({
+ arguments: [],
+ function: 'or',
+ type: 'function',
+ });
  });
 });