diff --git a/test/unit/connection-pool.test.js b/test/unit/connection-pool.test.js
index cf054aade..734877d1f 100644
--- a/test/unit/connection-pool.test.js
+++ b/test/unit/connection-pool.test.js
@@ -490,3 +490,80 @@ test('API', t => {
 
   t.end()
 })
+
+test('Node selector', t => {
+  t.test('round-robin', t => {
+    t.plan(1)
+    const pool = new ConnectionPool({ Connection, nodeSelector: 'round-robin' })
+    pool.addConnection('http://localhost:9200/')
+    t.true(pool.getConnection() instanceof Connection)
+  })
+
+  t.test('random', t => {
+    t.plan(1)
+    const pool = new ConnectionPool({ Connection, nodeSelector: 'random' })
+    pool.addConnection('http://localhost:9200/')
+    t.true(pool.getConnection() instanceof Connection)
+  })
+
+  t.test('custom function', t => {
+    t.plan(2)
+    const nodeSelector = connections => {
+      t.ok('called')
+      return connections[0]
+    }
+    const pool = new ConnectionPool({ Connection, nodeSelector })
+    pool.addConnection('http://localhost:9200/')
+    t.true(pool.getConnection() instanceof Connection)
+  })
+
+  t.end()
+})
+
+test('Node filter', t => {
+  t.test('default', t => {
+    t.plan(1)
+    const pool = new ConnectionPool({ Connection })
+    pool.addConnection({ url: new URL('http://localhost:9200/') })
+    t.true(pool.getConnection() instanceof Connection)
+  })
+
+  t.test('Should filter master only nodes', t => {
+    t.plan(1)
+    const pool = new ConnectionPool({ Connection })
+    pool.addConnection({
+      url: new URL('http://localhost:9200/'),
+      roles: {
+        master: true,
+        data: false,
+        ingest: false,
+        ml: false
+      }
+    })
+    t.strictEqual(pool.getConnection(), null)
+  })
+
+  t.test('custom', t => {
+    t.plan(2)
+    const nodeFilter = node => {
+      t.ok('called')
+      return true
+    }
+    const pool = new ConnectionPool({ Connection, nodeFilter })
+    pool.addConnection({ url: new URL('http://localhost:9200/') })
+    t.true(pool.getConnection() instanceof Connection)
+  })
+
+  t.test('custom (filter)', t => {
+    t.plan(2)
+    const nodeFilter = node => {
+      t.ok('called')
+      return false
+    }
+    const pool = new ConnectionPool({ Connection, nodeFilter })
+    pool.addConnection({ url: new URL('http://localhost:9200/') })
+    t.strictEqual(pool.getConnection(), null)
+  })
+
+  t.end()
+})
diff --git a/test/unit/connection.test.js b/test/unit/connection.test.js
index 8eb248c9b..92d6c6921 100644
--- a/test/unit/connection.test.js
+++ b/test/unit/connection.test.js
@@ -591,3 +591,63 @@ test('Should disallow two-byte characters in URL path', t => {
     )
   })
 })
+
+test('setRole', t => {
+  t.test('Update the value of a role', t => {
+    t.plan(2)
+
+    const connection = new Connection({
+      url: new URL('http://localhost:9200')
+    })
+
+    t.deepEqual(connection.roles, {
+      master: true,
+      data: true,
+      ingest: true,
+      ml: false
+    })
+
+    connection.setRole('master', false)
+
+    t.deepEqual(connection.roles, {
+      master: false,
+      data: true,
+      ingest: true,
+      ml: false
+    })
+  })
+
+  t.test('Invalid role', t => {
+    t.plan(2)
+
+    const connection = new Connection({
+      url: new URL('http://localhost:9200')
+    })
+
+    try {
+      connection.setRole('car', true)
+      t.fail('Shoud throw')
+    } catch (err) {
+      t.true(err instanceof ConfigurationError)
+      t.is(err.message, 'Unsupported role: \'car\'')
+    }
+  })
+
+  t.test('Invalid value', t => {
+    t.plan(2)
+
+    const connection = new Connection({
+      url: new URL('http://localhost:9200')
+    })
+
+    try {
+      connection.setRole('master', 1)
+      t.fail('Shoud throw')
+    } catch (err) {
+      t.true(err instanceof ConfigurationError)
+      t.is(err.message, 'enabled should be a boolean')
+    }
+  })
+
+  t.end()
+})
diff --git a/test/unit/transport.test.js b/test/unit/transport.test.js
index 45a2ada5d..3cc88c9ce 100644
--- a/test/unit/transport.test.js
+++ b/test/unit/transport.test.js
@@ -377,6 +377,32 @@ test('SerializationError', t => {
   })
 })
 
+test('SerializationError (bulk)', t => {
+  t.plan(1)
+  const pool = new ConnectionPool({ Connection })
+  pool.addConnection('http://localhost:9200')
+
+  const transport = new Transport({
+    emit: () => {},
+    connectionPool: pool,
+    serializer: new Serializer(),
+    maxRetries: 3,
+    requestTimeout: 30000,
+    sniffInterval: false,
+    sniffOnStart: false
+  })
+
+  const bulkBody = { hello: 'world' }
+  bulkBody.o = bulkBody
+  transport.request({
+    method: 'POST',
+    path: '/hello',
+    bulkBody
+  }, (err, { body }) => {
+    t.ok(err instanceof SerializationError)
+  })
+})
+
 test('DeserializationError', t => {
   t.plan(1)
   function handler (req, res) {