feat: add metadataCallback to CallOptions (#9298)

Author: Hectorhammett

Gax/src/Options/CallOptions.php

@@ -52,6 +52,9 @@ class CallOptions implements ArrayAccess, OptionsInterface
     private ?int $timeoutMillis;
     private array $transportOptions;
 
+    /** @var callable|null $metadataCallback */
+    private $metadataCallback;
+
     /** @var RetrySettings|array|null $retrySettings */
     private $retrySettings;
 
@@ -88,6 +91,7 @@ private function fromArray(array $arr): void
         $this->setTimeoutMillis($arr['timeoutMillis'] ?? null);
         $this->setTransportOptions($arr['transportOptions'] ?? []);
         $this->setRetrySettings($arr['retrySettings'] ?? null);
+        $this->setMetadataCallback($arr['metadataCallback'] ?? null);
     }
 
     /**
@@ -157,4 +161,11 @@ public function setRetrySettings($retrySettings): self
 
         return $this;
     }
+
+    public function setMetadataCallback(callable|null $metadataCallback): self
+    {
+        $this->metadataCallback = $metadataCallback;
+
+        return $this;
+    }
 }

Gax/tests/Unit/GapicClientTraitTest.php

@@ -1682,8 +1682,10 @@ public function testCallOptionsForV2Surface()
                 ]),
                 'timeoutMillis' => null, // adds null timeoutMillis,
                 'transportOptions' => [],
+                'metadataCallback' => null,
             ]
         )
+
             ->shouldBeCalledOnce()
             ->willReturn(new FulfilledPromise(new Operation()));
 

Gax/tests/Unit/Options/CallOptionsTest.php

@@ -0,0 +1,67 @@
+<?php
+/*
+ * Copyright 2026 Google LLC
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+namespace Google\ApiCore\Tests\Unit\Options;
+
+use Google\ApiCore\Options\CallOptions;
+use PHPUnit\Framework\TestCase;
+
+class CallOptionsTest extends TestCase
+{
+    public function testCallOptionsInstantiation()
+    {
+        $callback = function (array $headers) {
+            return;
+        };
+        $options = new CallOptions([
+            'headers' => ['foo' => ['bar']],
+            'timeoutMillis' => 100,
+            'metadataCallback' => $callback,
+            'transportOptions' => ['baz' => 'qux'],
+        ]);
+
+        $optionsArray = $options->toArray();
+        $this->assertEquals(['foo' => ['bar']], $optionsArray['headers']);
+        $this->assertEquals(100, $optionsArray['timeoutMillis']);
+        $this->assertEquals(['baz' => 'qux'], $optionsArray['transportOptions']);
+        $this->assertSame($callback, $optionsArray['metadataCallback']);
+    }
+
+    public function testUnrecognizedOptionsAreIgnored()
+    {
+        $options = new CallOptions([
+            'unrecognizedOption' => 'value',
+        ]);
+
+        $this->assertArrayNotHasKey('unrecognizedOption', $options->toArray());
+    }
+}