fix: provide missing close() method in the generated gapic client (#941)

* fix: backport the close() method to the publisher client from the typescript gapic generator

* fix: add the publisher_client.js hack to synth.py and update publisher_client.js to match it

* fix: add a system-test to verify that calling close() works

Co-authored-by: Justin Beckwith <justin.beckwith@gmail.com>

src/v1/publisher_client.js

@@ -222,6 +222,8 @@ class PublisherClient {
 
     // Iterate over each of the methods that the service provides
     // and create an API call method for each.
+    // note: editing generated code
+    this.publisherStub = publisherStub;
     const publisherStubMethods = [
       'createTopic',
       'updateTopic',
@@ -1170,6 +1172,18 @@ class PublisherClient {
     });
   }
 
+  /**
+   * Terminate the GRPC channel and close the client.
+   * note: editing generated code
+   *
+   * The client will no longer be usable and all future behavior is undefined.
+   */
+  close() {
+    return this.publisherStub.then(stub => {
+      stub.close();
+    });
+  }
+
   /**
    * Parse the projectName from a project resource.
    *

synth.py

@@ -40,6 +40,29 @@
           "    };\n"
           "\g<0>")
 
+# The JavaScript generator didn't implement close(). TypeScript gapic does,
+# so this should be removed when we merge that.
+s.replace("src/v1/publisher_client.js",
+          "   \* Parse the projectName from a project resource.\n",
+          "   * Terminate the GRPC channel and close the client.\n"
+          "   * note: editing generated code\n"
+          "   *\n"
+          "   * The client will no longer be usable and all future behavior is undefined.\n"
+          "   */\n"
+          "  close() {\n"
+          "    return this.publisherStub.then(stub => {\n"
+          "      stub.close();\n"
+          "    });\n"
+          "  }\n"
+          "  \n"
+          "  /**\n"
+          "  \g<0>")
+s.replace("src/v1/publisher_client.js",
+          "    const publisherStubMethods = \\[\n",
+          "    // note: editing generated code\n"
+          "    this.publisherStub = publisherStub;\n"
+          "    \g<0>")
+
 # Update path discovery due to build/ dir and TypeScript conversion.
 s.replace("src/v1/publisher_client.js", "../../package.json", "../../../package.json")
 s.replace("src/v1/subscriber_client.js", "../../package.json", "../../../package.json")

system-test/pubsub.ts

@@ -888,4 +888,17 @@ describe('pubsub', () => {
       });
     });
   });
+
+  it('should allow closing of publisher clients', async () => {
+    // The full call stack of close() is tested in unit tests; this is mostly
+    // to verify that the close() method is actually there and doesn't error.
+    const localPubsub = new PubSub();
+
+    // Just use the client object to make sure it has opened a connection.
+    await pubsub.getTopics();
+
+    // Tell it to close, and validate that it's marked closed.
+    await localPubsub.close();
+    assert.strictEqual(localPubsub.isOpen, false);
+  });
 });