diff --git a/tests/unit/PubSub/Connection/GrpcTest.php b/tests/unit/PubSub/Connection/GrpcTest.php
index c7b28a2cfab0..994a35c00810 100644
--- a/tests/unit/PubSub/Connection/GrpcTest.php
+++ b/tests/unit/PubSub/Connection/GrpcTest.php
@@ -114,6 +114,11 @@ public function methodProvider()
         $timestamp = $serializer->decodeMessage(new Timestamp(), $this->formatTimestampForApi($time));
 
         return [
+            [
+                'updateSubscription',
+                ['name' => 'projects/foo/subscriptions/bar', 'retainAckedMessages' => true],
+                [$subscription, $fieldMask, []]
+            ],
             [
                 'listSnapshots',
                 ['project' => 'projectId'],
diff --git a/tests/unit/PubSub/Connection/RestTest.php b/tests/unit/PubSub/Connection/RestTest.php
index 5f1643ed4343..49af5829bd68 100644
--- a/tests/unit/PubSub/Connection/RestTest.php
+++ b/tests/unit/PubSub/Connection/RestTest.php
@@ -84,6 +84,7 @@ public function methodProvider()
             ['setTopicIamPolicy'],
             ['testTopicIamPermissions'],
             ['createSubscription'],
+            ['updateSubscription'],
             ['getSubscription'],
             ['listSubscriptions'],
             ['deleteSubscription'],
diff --git a/tests/unit/PubSub/SubscriptionTest.php b/tests/unit/PubSub/SubscriptionTest.php
index 1d67ebc52c1f..85ea771796d0 100644
--- a/tests/unit/PubSub/SubscriptionTest.php
+++ b/tests/unit/PubSub/SubscriptionTest.php
@@ -86,6 +86,28 @@ public function testCreateWithoutTopicName()
         $sub = $subscription->create();
     }
 
+    public function testUpdate()
+    {
+        $args = [
+            'foo' => 'bar'
+        ];
+
+        $argsWithName = $args + [
+            'name' => $this->subscription->name()
+        ];
+
+        $this->connection->updateSubscription($argsWithName)
+            ->shouldBeCalled()
+            ->willReturn($argsWithName);
+
+        $this->subscription->setConnection($this->connection->reveal());
+
+        $res = $this->subscription->update($args);
+
+        $this->assertEquals($res, $argsWithName);
+        $this->assertEquals($this->subscription->info(), $argsWithName);
+    }
+
     public function testDelete()
     {
         $this->connection->deleteSubscription(Argument::withEntry('foo', 'bar'))