StackdriverExporter should report g.co/agent attribute (#4)

Author: chingor13

src/StackdriverExporter.php

@@ -24,6 +24,7 @@
 use Google\Cloud\Trace\Trace;
 use OpenCensus\Trace\SpanData;
 use OpenCensus\Trace\Exporter\Stackdriver\SpanConverter;
+use OpenCensus\Version;
 
 /**
  * This implementation of the ExporterInterface use the BatchRunner to provide
@@ -71,6 +72,8 @@
  */
 class StackdriverExporter implements ExporterInterface
 {
+    const AGENT = 'g.co/agent';
+
     use BatchTrait;
 
     /**
@@ -144,8 +147,13 @@ public function export(array $spans)
 
         // Pull the traceId from the first span
         $spans = array_map([SpanConverter::class, 'convertSpan'], $spans);
+        $rootSpan = $spans[0];
         $trace = self::$client->trace(
-            $spans[0]->traceId()
+            $rootSpan->traceId()
+        );
+        $rootSpan->addAttribute(
+            self::AGENT,
+            sprintf('opencensus-php [%s]', Version::VERSION)
         );
 
         // build a Trace object and assign Spans

tests/unit/StackdriverExporterTest.php

@@ -83,4 +83,28 @@ public function testEmptyTrace()
         $exporter = new StackdriverExporter(['client' => $this->client->reveal()]);
         $this->assertFalse($exporter->export([]));
     }
+
+    public function testReportsVersionAttribute()
+    {
+        $trace = $this->prophesize(Trace::class);
+        $trace->setSpans(Argument::that(function ($spans) {
+            $this->assertCount(1, $spans);
+            $attributes = $spans[0]->jsonSerialize()['attributes'];
+            $this->assertArrayHasKey('g.co/agent', $attributes);
+            $this->assertRegexp('/\d+\.\d+\.\d+/', $attributes['g.co/agent']);
+            return true;
+        }))->shouldBeCalled();
+        $this->client->trace('aaa')->willReturn($trace->reveal());
+        $this->client->insert(Argument::type(Trace::class))
+            ->willReturn(true)->shouldBeCalled();
+
+        $span = new OCSpan([
+            'traceId' => 'aaa'
+        ]);
+        $span->setStartTime();
+        $span->setEndTime();
+
+        $exporter = new StackdriverExporter(['client' => $this->client->reveal()]);
+        $this->assertTrue($exporter->export([$span->spanData()]));
+    }
 }