Integration PubSub Extension

Integration: Google Cloud Pub/Sub Extension

Track Google Cloud Pub/Sub operations in your test diagrams using the TestTrackingDiagrams.Extensions.PubSub NuGet package. This extension wraps PublisherClient and SubscriberClient to capture publish/subscribe operations.

Using a shared library or abstraction layer? If your code doesn't use the Pub/Sub SDK directly — e.g. it goes through a shared messaging library, wrapper, or custom abstraction — this extension won't be able to intercept the underlying calls. See Tracking Custom Dependencies for alternative approaches including MessageTracker and TrackingProxy<T>.

Installation

dotnet add package TestTrackingDiagrams.Extensions.PubSub

Quick Start

Publisher

using TestTrackingDiagrams.Extensions.PubSub;

var publisher = await PublisherClient.CreateAsync(topicName);
var trackingPublisher = new TrackingPublisherClient(publisher, new PubSubTrackingOptions
{
    ServiceName = "PubSub",
    CallingServiceName = "OrdersApi",
    CurrentTestInfoFetcher = () => (TestContext.CurrentTestName, TestContext.CurrentTestId)
});

await trackingPublisher.PublishAsync("Hello, Pub/Sub!");

Subscriber

var subscriber = await SubscriberClient.CreateAsync(subscriptionName);
var trackingSubscriber = new TrackingSubscriberClient(subscriber, new PubSubTrackingOptions
{
    ServiceName = "PubSub",
    CallingServiceName = "WorkerService",
    CurrentTestInfoFetcher = () => (TestContext.CurrentTestName, TestContext.CurrentTestId)
});

await trackingSubscriber.StartAsync(async (msg, ct) =>
{
    // Process message
    return SubscriberClient.Reply.Ack;
});

How It Works

Google Cloud Pub/Sub uses gRPC internally, so DelegatingHandler interception is not viable. Instead, this extension uses a wrapper/decorator pattern:

• TrackingPublisherClient wraps PublisherClient and logs publish operations
• TrackingSubscriberClient wraps SubscriberClient and intercepts the message handler callback

PubSubTracker

Both wrappers use PubSubTracker as a central logging helper. It implements ITrackingComponent and handles request/response logging with RequestResponseMetaType.Event for messaging semantics.

Supported Operations

Operation	Enum Value	Source
Publish (single)	PubSubOperation.Publish	TrackingPublisherClient
Publish (batch)	PubSubOperation.PublishBatch	TrackingPublisherClient
Receive	PubSubOperation.Receive	TrackingSubscriberClient callback
Pull	PubSubOperation.Pull	Low-level API
Acknowledge	PubSubOperation.Acknowledge	Low-level API
ModifyAckDeadline	PubSubOperation.ModifyAckDeadline	Low-level API
StartSubscriber	PubSubOperation.StartSubscriber	Lifecycle
StopSubscriber	PubSubOperation.StopSubscriber	Lifecycle

Resource Name Extraction

GCP Pub/Sub uses full resource paths like projects/my-project/topics/my-topic. At Detailed verbosity, short names are extracted:

• projects/my-project/topics/my-topic → my-topic
• projects/my-project/subscriptions/my-sub → my-sub

Verbosity Levels

PubSubTrackingVerbosity.Summarised

• Label: Operation name (e.g. Publish)
• Content: Omitted
• URI: pubsub:///my-topic

PubSubTrackingVerbosity.Detailed

• Label: Operation with target (e.g. Publish → my-topic, Receive ← my-sub)
• Content: Message data (UTF-8 text)
• URI: pubsub:///my-topic

PubSubTrackingVerbosity.Raw

• Label: Full info including resource paths
• Content: Message data + response details
• URI: pubsub:///projects/p/topics/my-topic

Configuration

DI Registration (v2.23.11+)

Recommended. Registers a singleton PubSubTracker in DI with IHttpContextAccessor automatically resolved. Consumers can then inject PubSubTracker when constructing wrapper clients.

// In your test's ConfigureTestServices:
services.AddPubSubTestTracking(options =>
{
    options.ServiceName = "PubSub";
    options.CallingServiceName = "OrdersApi";
    options.CurrentTestInfoFetcher = () => (TestContext.Current!.Test.TestDisplayName, TestContext.Current.Test.UniqueID);
});

Then use the tracker when creating wrapper clients:

// Resolve from DI:
var tracker = sp.GetRequiredService<PubSubTracker>();
var publisher = await PublisherClient.CreateAsync(topicName);
var trackingPublisher = new TrackingPublisherClient(publisher, new PubSubTrackingOptions
{
    ServiceName = "PubSub",
    CallingServiceName = "OrdersApi",
    CurrentTestInfoFetcher = /* same as above */
});

Manual Configuration

new PubSubTrackingOptions
{
    ServiceName = "PubSub",
    CallingServiceName = "OrdersApi",
    Verbosity = PubSubTrackingVerbosity.Detailed,
    CurrentTestInfoFetcher = () => (testName, testId)
}

PubSubTrackingOptions

Property	Type	Default	Description
ServiceName	string	"PubSub"	Display name in diagrams for the Pub/Sub service
CallingServiceName	string	"Caller"	Calling service name in diagrams
Verbosity	PubSubTrackingVerbosity	Detailed	Verbosity level (Raw, Detailed, Summarised)
CurrentTestInfoFetcher	Func<(string Name, string Id)>?	null	Required: provides test context for log correlation
CurrentStepTypeFetcher	Func<string?>?	null	Optional — returns the current BDD step type (Given/When/Then)

v2.23.0+ Dual-Resolution: PubSubTracker accepts an optional IHttpContextAccessor? httpContextAccessor constructor parameter for resolving test identity from HTTP request headers when running inside the SUT's request pipeline. See HTTP Tracking Setup#Dual-Resolution Test Identity (v2.23.0+) for details. The AddPubSubTestTracking() DI helper (v2.23.11+) resolves this automatically. | SetupVerbosity | PubSubTrackingVerbosity? | null | Verbosity override for the Setup phase. See Phase-Aware Tracking | | ActionVerbosity | PubSubTrackingVerbosity? | null | Verbosity override for the Action phase. See Phase-Aware Tracking | | TrackDuringSetup | bool | true | When false, tracking is suppressed during Setup. See Phase-Aware Tracking | | TrackDuringAction | bool | true | When false, tracking is suppressed during Action. See Phase-Aware Tracking |

ITrackingComponent

PubSubTracker implements ITrackingComponent and auto-registers:

• ComponentName: "PubSubTracker ({ServiceName})"
• WasInvoked: true after first operation
• InvocationCount: Total operations logged

See Also

• Integration: SQS Extension
• Integration: Amazon DynamoDB Extension
• Integration: Azure Service Bus Extension