Hybrid Cloud Test GenCAUTION

Developer-first error tracking and performance monitoring

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---
name: hybrid-cloud-test-gen
description: Generate hybrid cloud tests for the Sentry codebase. Use when asked to "generate HC test", "create hybrid cloud test", "write HC test", "add HC test", "write RPC test", "test RPC service", "silo test", "cross-silo test", "outbox test", "API gateway test", or "endpoint silo test". Covers RPC service tests, API gateway tests, outbox pattern tests, and API endpoint tests with silo decorators.
---

# Hybrid Cloud Test Generation

This skill generates tests for Sentry's hybrid cloud architecture. It covers RPC services, API gateway proxying, outbox patterns, and endpoint silo decorators.

## Critical Constraints

> **ALWAYS** use factory methods (`self.create_user()`, `self.create_organization()`) — never `Model.objects.create()`.

> **NEVER** wrap factory method calls in `assume_test_silo_mode` or `assume_test_silo_mode_of`. Factories are silo-aware and handle silo mode internally. Only use silo mode context managers for direct ORM queries (`Model.objects.get/filter/count/exists/delete`).

> **ALWAYS** use `pytest`-style assertions (`assert x == y`) — never `self.assertEqual()`.

> **ALWAYS** add tests to existing test files rather than creating new ones, unless no file exists for that module.

> For cross-silo ORM access: use `assume_test_silo_mode_of(Model)` when accessing a single model (auto-detects silo). Use `assume_test_silo_mode(SiloMode.X)` when the block covers multiple models or non-model operations.

> Use `TestCase` for most tests, including those using `outbox_runner()`. Only use `TransactionTestCase` when tests need real committed transactions (threading, concurrency, multi-process scenarios).

> **NEVER** use `from __future__ import annotations` in test files that deal with RPC models.

## Step 1: Identify Test Category

Determine which category of HC test to generate based on the user's request:

| Signal                                                              | Category             | Go To  |
| ------------------------------------------------------------------- | -------------------- | ------ |
| RPC service, service method, serialization round-trip, dispatch     | RPC Service Tests    | Step 3 |
| API gateway, proxy, middleware, forwarding                          | API Gateway Tests    | Step 4 |
| Outbox, cross-silo message, ControlOutbox, CellOutbox, outbox drain | Outbox Pattern Tests | Step 5 |
| API endpoint with silo decorator, endpoint test, permission check   | Endpoint Silo Tests  | Step 6 |

If the signal is ambiguous, ask the user to clarify which category.

## Step 2: Gather Context

Before generating any test:

1. **Read the source module** being tested. Determine its silo mode by checking for `@cell_silo_endpoint`, `@control_silo_endpoint`, `local_mode = SiloMode.X`, or `@cell_silo_model`/`@control_silo_model` decorators.

2. **Find the existing test file** using the mirror path convention:
   - `src/sentry/foo/bar.py` → `tests/sentry/foo/test_bar.py`
   - `src/sentry/foo/services/bar/service.py` → `tests/sentry/foo/services/test_bar.py`
   - `src/sentry/foo/services/bar/impl.py` → `tests/sentry/foo/services/test_bar.py`

3. **Read the existing test file** to understand what's already tested, what base classes are used, and what patterns are established.

4. **Read source method signatures** to understand parameters, return types, and which RPC models are involved.

## Step 3: Generate RPC Service Tests

Load `references/rpc-service-tests.md` for complete templates and patterns.

RPC service tests must cover:

- **Silo compatibility**: `@all_silo_test` ensures the service works across all silo modes
- **Serialization round-trip**: `dispatch_to_local_service` verifies args/return survive serialization
- **Field accuracy**: Field-by-field comparison of RPC model against ORM object
- **Error handling**: Not-found returns, disabled methods, remote exception wrapping
- **Cross-silo effects**: `outbox_runner()` + `assume_test_silo_mode` for propagation checks

### Quick Reference — Decorator & Base Class

| Scenario                           | Decorator                                       | Base Class                       |
| ---------------------------------- | ----------------------------------------------- | -------------------------------- |
| Standard RPC service               | `@all_silo_test`                                | `TestCase`                       |
| RPC with named cells               | `@all_silo_test(cells=create_test_cells("us"))` | `TestCase`                       |
| RPC with member mapping assertions | `@all_silo_test`                                | `TestCase, HybridCloudTestMixin` |

## Step 4: Generate API Gateway Tests

Load `references/api-gateway-tests.md` for complete templates and patterns.

API gateway tests verify that requests to control-silo endpoints are correctly proxied to the appropriate cell. They must cover:

- **Proxy pass-through**: Requests forwarded with correct params, headers, body
- **Query parameter forwarding**: Multi-value params preserved
- **Error proxying**: Upstream errors forwarded correctly
- **Streaming responses**: `close_streaming_response()` for reading proxied response body

### Quick Reference — Decorator & Base Class

| Scenario              | Decorator                                                                        | Base Class           |
| --------------------- | -------------------------------------------------------------------------------- | -------------------- |
| Standard gateway test | `@control_silo_test(cells=[ApiGatewayTestCase.CELL], include_monolith_run=True)` | `ApiGatewayTestCase` |

## Step 5: Generate Outbox Pattern Tests

Load `references/outbox-tests.md` for complete templates and patterns.

Outbox tests verify that cross-silo messages are created, drained, and produce the expected side effects. They must cover:

- **Outbox creation**: Verify correct outbox records with `outbox_context(flush=False)`
- **Outbox processi

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