Add test to verify default node filter function (#2756)

test/unit/client.test.ts

@@ -64,6 +64,31 @@ test('Missing node(s)', t => {
   t.end()
 })
 
+test('multi nodes with roles, using default node filter', async t => {
+  const client = new Client({
+    nodes: [
+      {
+        url: new URL('http://node1:9200'),
+        roles: { master: true, data: false, ingest: false, ml: false }
+      },
+      {
+        url: new URL('http://node2:9200'),
+        roles: { master: true, data: true, ingest: false, ml: false }
+      },
+    ]
+  })
+  const conn = client.connectionPool.getConnection({
+    now: Date.now() + 1000 * 60 * 3,
+    requestId: 1,
+    name: 'elasticsearch-js',
+    context: null
+  })
+
+  t.equal(conn?.url.hostname, 'node2')
+
+  t.end()
+})
+
 test('Custom headers', t => {
   const client = new Client({
     node: 'http://localhost:9200',