Support PHP generic services (#3269)

* Add php_generic_services option

* Generate PHP generic services

* Respect namespaces for generated PHP services

* Test PHP generated services

* Rename PHP generator service method doc comment function

* Correct phpdoc service method case

* Test namespaced PHP generic services

* Always use the FQCN for PHP generic service input/output

* Add generated_service_test to php test.sh

* Add php service test protos to CI

* Add php service files to php_EXTRA_DIST

* Use Interface suffix for php generic services

php/tests/generated_service_test.php

diff --git a/php/tests/generated_service_test.php b/php/tests/generated_service_test.php
new file mode 100644
index 0000000..5407db9
--- /dev/null
+++ b/php/tests/generated_service_test.php
@@ -0,0 +1,110 @@
+<?php
+
+require_once('test_base.php');
+require_once('test_util.php');
+
+use Google\Protobuf\Internal\RepeatedField;
+use Google\Protobuf\Internal\MapField;
+use Google\Protobuf\Internal\GPBType;
+use Foo\Greeter;
+use Foo\HelloRequest;
+use Foo\HelloReply;
+
+class GeneratedServiceTest extends TestBase
+{
+    /**
+     * @var \ReflectionClass
+     */
+    private $serviceClass;
+
+    /**
+     * @var \ReflectionClass
+     */
+    private $namespacedServiceClass;
+
+    /**
+     * @var array
+     */
+    private $methodNames = [
+        'sayHello',
+        'sayHelloAgain'
+    ];
+
+    public function setUp()
+    {
+        parent::setUp();
+
+        $this->serviceClass = new ReflectionClass('Foo\GreeterInterface');
+
+        $this->namespacedServiceClass = new ReflectionClass('Bar\OtherGreeterInterface');
+    }
+
+    public function testIsInterface()
+    {
+        $this->assertTrue($this->serviceClass->isInterface());
+    }
+
+    public function testPhpDocForClass()
+    {
+        $this->assertContains('foo.Greeter', $this->serviceClass->getDocComment());
+    }
+
+    public function testPhpDocForNamespacedClass()
+    {
+        $this->assertContains('foo.OtherGreeter', $this->namespacedServiceClass->getDocComment());
+    }
+
+    public function testServiceMethodsAreGenerated()
+    {
+        $this->assertCount(count($this->methodNames), $this->serviceClass->getMethods());
+        foreach ($this->methodNames as $methodName) {
+            $this->assertTrue($this->serviceClass->hasMethod($methodName));
+        }
+    }
+
+    public function testPhpDocForServiceMethod()
+    {
+        foreach ($this->methodNames as $methodName) {
+            $docComment = $this->serviceClass->getMethod($methodName)->getDocComment();
+            $this->assertContains($methodName, $docComment);
+            $this->assertContains('@param \Foo\HelloRequest $request', $docComment);
+            $this->assertContains('@return \Foo\HelloReply', $docComment);
+        }
+    }
+
+    public function testPhpDocForServiceMethodInNamespacedClass()
+    {
+        foreach ($this->methodNames as $methodName) {
+            $docComment = $this->namespacedServiceClass->getMethod($methodName)->getDocComment();
+            $this->assertContains($methodName, $docComment);
+            $this->assertContains('@param \Foo\HelloRequest $request', $docComment);
+            $this->assertContains('@return \Foo\HelloReply', $docComment);
+        }
+    }
+
+    public function testParamForServiceMethod()
+    {
+        foreach ($this->methodNames as $methodName) {
+            $method = $this->serviceClass->getMethod($methodName);
+            $this->assertCount(1, $method->getParameters());
+            $param = $method->getParameters()[0];
+            $this->assertFalse($param->isOptional());
+            $this->assertSame('request', $param->getName());
+            // ReflectionParameter::getType only exists in PHP 7+, so get the type from __toString
+            $this->assertContains('Foo\HelloRequest $request', (string) $param);
+        }
+    }
+
+    public function testParamForServiceMethodInNamespacedClass()
+    {
+        foreach ($this->methodNames as $methodName) {
+            $method = $this->serviceClass->getMethod($methodName);
+            $this->assertCount(1, $method->getParameters());
+            $param = $method->getParameters()[0];
+            $this->assertFalse($param->isOptional());
+            $this->assertSame('request', $param->getName());
+            // ReflectionParameter::getType only exists in PHP 7+, so get the type from __toString
+            $this->assertContains('Foo\HelloRequest $request', (string) $param);
+        }
+    }
+}