|
| 1 | +# Durable Task Testing Utilities |
| 2 | + |
| 3 | +This package provides testing utilities for the Durable Task Python SDK, |
| 4 | +including an in-memory backend that eliminates the need for external |
| 5 | +dependencies during testing. |
| 6 | + |
| 7 | +## In-Memory Backend |
| 8 | + |
| 9 | +The `InMemoryOrchestrationBackend` is a lightweight, in-memory implementation |
| 10 | +of the Durable Task backend that runs as a gRPC server. It's designed for |
| 11 | +testing scenarios where you want to test orchestrations without requiring a |
| 12 | +sidecar process or external storage. |
| 13 | + |
| 14 | +### Features |
| 15 | + |
| 16 | +- **In-memory state storage**: All orchestration state is stored in memory |
| 17 | +- **Full gRPC compatibility**: Implements the same gRPC interface as the production backend |
| 18 | +- **Thread-safe**: Safe for concurrent access from multiple threads |
| 19 | +- **Work item streaming**: Supports streaming work items to workers |
| 20 | +- **Event handling**: Supports raising events, timers, and sub-orchestrations |
| 21 | +- **Entity support**: Supports function-based and class-based entities |
| 22 | +- **Lifecycle management**: Supports suspend, resume, and terminate operations |
| 23 | +- **State waiting**: Built-in support for waiting on orchestration state changes |
| 24 | + |
| 25 | +### Quick Start |
| 26 | + |
| 27 | +```python |
| 28 | +import pytest |
| 29 | +from durabletask.testing import create_test_backend |
| 30 | +from durabletask.client import TaskHubGrpcClient, OrchestrationStatus |
| 31 | +from durabletask.worker import TaskHubGrpcWorker |
| 32 | + |
| 33 | +@pytest.fixture |
| 34 | +def backend(): |
| 35 | + """Create an in-memory backend for testing.""" |
| 36 | + backend = create_test_backend(port=50051) |
| 37 | + yield backend |
| 38 | + backend.stop() |
| 39 | + backend.reset() |
| 40 | + |
| 41 | +def test_simple_orchestration(backend): |
| 42 | + # Create client and worker |
| 43 | + client = TaskHubGrpcClient(host_address="localhost:50051") |
| 44 | + worker = TaskHubGrpcWorker(host_address="localhost:50051") |
| 45 | + |
| 46 | + # Define orchestrator and activity |
| 47 | + def hello_orchestrator(ctx, _): |
| 48 | + result = yield ctx.call_activity(say_hello, input="World") |
| 49 | + return result |
| 50 | + |
| 51 | + def say_hello(ctx, name: str): |
| 52 | + return f"Hello, {name}!" |
| 53 | + |
| 54 | + # Register orchestrator and activity with the worker |
| 55 | + worker.add_orchestrator(hello_orchestrator) |
| 56 | + worker.add_activity(say_hello) |
| 57 | + |
| 58 | + # Start worker |
| 59 | + worker.start() |
| 60 | + |
| 61 | + try: |
| 62 | + # Schedule orchestration |
| 63 | + instance_id = client.schedule_new_orchestration(hello_orchestrator) |
| 64 | + |
| 65 | + # Wait for completion |
| 66 | + state = client.wait_for_orchestration_completion(instance_id, timeout=10) |
| 67 | + |
| 68 | + # Verify results |
| 69 | + assert state.runtime_status == OrchestrationStatus.COMPLETED |
| 70 | + assert state.serialized_output == '"Hello, World!"' |
| 71 | + finally: |
| 72 | + worker.stop() |
| 73 | +``` |
| 74 | + |
| 75 | +### Advanced Usage |
| 76 | + |
| 77 | +#### Testing with Multiple Ports |
| 78 | + |
| 79 | +```python |
| 80 | +import random |
| 81 | +import pytest |
| 82 | +from durabletask.testing import create_test_backend |
| 83 | +from durabletask.client import TaskHubGrpcClient |
| 84 | +from durabletask.worker import TaskHubGrpcWorker |
| 85 | + |
| 86 | +@pytest.fixture |
| 87 | +def backend(): |
| 88 | + # Use a random port to avoid conflicts |
| 89 | + port = random.randint(50000, 60000) |
| 90 | + backend = create_test_backend(port=port) |
| 91 | + yield backend, port |
| 92 | + backend.stop() |
| 93 | + backend.reset() |
| 94 | + |
| 95 | +def test_orchestration(backend): |
| 96 | + backend_instance, port = backend |
| 97 | + client = TaskHubGrpcClient(host_address=f"localhost:{port}") |
| 98 | + worker = TaskHubGrpcWorker(host_address=f"localhost:{port}") |
| 99 | + # ... |
| 100 | +``` |
| 101 | + |
| 102 | +#### Testing Event Handling |
| 103 | + |
| 104 | +```python |
| 105 | +def test_external_events(backend): |
| 106 | + client = TaskHubGrpcClient(host_address="localhost:50051") |
| 107 | + worker = TaskHubGrpcWorker(host_address="localhost:50051") |
| 108 | + |
| 109 | + def wait_for_event_orchestrator(ctx, _): |
| 110 | + event_data = yield ctx.wait_for_external_event("approval") |
| 111 | + return event_data |
| 112 | + |
| 113 | + worker.add_orchestrator(wait_for_event_orchestrator) |
| 114 | + worker.start() |
| 115 | + |
| 116 | + try: |
| 117 | + instance_id = client.schedule_new_orchestration(wait_for_event_orchestrator) |
| 118 | + |
| 119 | + # Wait for orchestration to start |
| 120 | + client.wait_for_orchestration_start(instance_id, timeout=5) |
| 121 | + |
| 122 | + # Raise an event |
| 123 | + client.raise_orchestration_event(instance_id, "approval", data="approved") |
| 124 | + |
| 125 | + # Wait for completion |
| 126 | + state = client.wait_for_orchestration_completion(instance_id, timeout=10) |
| 127 | + |
| 128 | + assert state.runtime_status == OrchestrationStatus.COMPLETED |
| 129 | + assert state.serialized_output == '"approved"' |
| 130 | + finally: |
| 131 | + worker.stop() |
| 132 | +``` |
| 133 | + |
| 134 | +#### Testing Sub-Orchestrations |
| 135 | + |
| 136 | +```python |
| 137 | +def test_sub_orchestrations(backend): |
| 138 | + client = TaskHubGrpcClient(host_address="localhost:50051") |
| 139 | + worker = TaskHubGrpcWorker(host_address="localhost:50051") |
| 140 | + |
| 141 | + def parent_orchestrator(ctx, _): |
| 142 | + result1 = yield ctx.call_sub_orchestrator(child_orchestrator, input=1) |
| 143 | + result2 = yield ctx.call_sub_orchestrator(child_orchestrator, input=2) |
| 144 | + return result1 + result2 |
| 145 | + |
| 146 | + def child_orchestrator(ctx, input: int): |
| 147 | + return input * 2 |
| 148 | + |
| 149 | + worker.add_orchestrator(parent_orchestrator) |
| 150 | + worker.add_orchestrator(child_orchestrator) |
| 151 | + worker.start() |
| 152 | + |
| 153 | + try: |
| 154 | + instance_id = client.schedule_new_orchestration(parent_orchestrator) |
| 155 | + state = client.wait_for_orchestration_completion(instance_id, timeout=10) |
| 156 | + |
| 157 | + assert state.runtime_status == OrchestrationStatus.COMPLETED |
| 158 | + assert state.serialized_output == "6" # (1*2) + (2*2) |
| 159 | + finally: |
| 160 | + worker.stop() |
| 161 | +``` |
| 162 | + |
| 163 | +#### Testing Timers |
| 164 | + |
| 165 | +```python |
| 166 | +def test_durable_timers(backend): |
| 167 | + import time |
| 168 | + from datetime import timedelta |
| 169 | + |
| 170 | + client = TaskHubGrpcClient(host_address="localhost:50051") |
| 171 | + worker = TaskHubGrpcWorker(host_address="localhost:50051") |
| 172 | + |
| 173 | + def timer_orchestrator(ctx, _): |
| 174 | + fire_at = ctx.current_utc_datetime + timedelta(seconds=1) |
| 175 | + yield ctx.create_timer(fire_at) |
| 176 | + return "timer_fired" |
| 177 | + |
| 178 | + worker.add_orchestrator(timer_orchestrator) |
| 179 | + worker.start() |
| 180 | + |
| 181 | + try: |
| 182 | + start_time = time.time() |
| 183 | + instance_id = client.schedule_new_orchestration(timer_orchestrator) |
| 184 | + state = client.wait_for_orchestration_completion(instance_id, timeout=10) |
| 185 | + elapsed = time.time() - start_time |
| 186 | + |
| 187 | + assert state.runtime_status == OrchestrationStatus.COMPLETED |
| 188 | + assert elapsed >= 1.0 # Timer should have waited at least 1 second |
| 189 | + finally: |
| 190 | + worker.stop() |
| 191 | +``` |
| 192 | + |
| 193 | +#### Testing Termination |
| 194 | + |
| 195 | +```python |
| 196 | +def test_orchestration_termination(backend): |
| 197 | + client = TaskHubGrpcClient(host_address="localhost:50051") |
| 198 | + worker = TaskHubGrpcWorker(host_address="localhost:50051") |
| 199 | + |
| 200 | + def long_running_orchestrator(ctx, _): |
| 201 | + yield ctx.wait_for_external_event("never_happens") |
| 202 | + return "completed" |
| 203 | + |
| 204 | + worker.add_orchestrator(long_running_orchestrator) |
| 205 | + worker.start() |
| 206 | + |
| 207 | + try: |
| 208 | + instance_id = client.schedule_new_orchestration(long_running_orchestrator) |
| 209 | + |
| 210 | + # Wait for it to start |
| 211 | + client.wait_for_orchestration_start(instance_id, timeout=5) |
| 212 | + |
| 213 | + # Terminate it |
| 214 | + client.terminate_orchestration(instance_id, output="terminated_by_test") |
| 215 | + |
| 216 | + # Verify termination |
| 217 | + state = client.wait_for_orchestration_completion(instance_id, timeout=10) |
| 218 | + |
| 219 | + assert state.runtime_status == OrchestrationStatus.TERMINATED |
| 220 | + finally: |
| 221 | + worker.stop() |
| 222 | +``` |
| 223 | + |
| 224 | +### Configuration Options |
| 225 | + |
| 226 | +The `InMemoryOrchestrationBackend` supports the following configuration options: |
| 227 | + |
| 228 | +- **port** (int): Port to listen on for gRPC connections (default: 50051) |
| 229 | +- **max_history_size** (int): Maximum number of history events per orchestration (default: 10000) |
| 230 | + |
| 231 | +```python |
| 232 | +backend = InMemoryOrchestrationBackend( |
| 233 | + port=50051, |
| 234 | + max_history_size=100000 # Support larger orchestrations |
| 235 | +) |
| 236 | +backend.start() |
| 237 | +``` |
| 238 | + |
| 239 | +Or use the convenience factory, which starts the server automatically: |
| 240 | + |
| 241 | +```python |
| 242 | +backend = create_test_backend(port=50051, max_history_size=10000) |
| 243 | +``` |
| 244 | + |
| 245 | +### Thread Safety |
| 246 | + |
| 247 | +The in-memory backend is thread-safe and can be safely accessed from |
| 248 | +multiple threads. All state mutations are protected by locks to ensure |
| 249 | +consistency. |
| 250 | + |
| 251 | +### Limitations |
| 252 | + |
| 253 | +The in-memory backend is designed for testing and has some limitations compared to production backends: |
| 254 | + |
| 255 | +1. **No persistence**: All state is lost when the backend is stopped |
| 256 | +2. **No distributed execution**: Runs in a single process |
| 257 | +3. **No history streaming**: StreamInstanceHistory is not implemented |
| 258 | +4. **No rewind**: RewindInstance is not implemented |
| 259 | + |
| 260 | +### Best Practices |
| 261 | + |
| 262 | +1. **Use fixtures**: Create pytest fixtures to manage backend lifecycle |
| 263 | +2. **Reset between tests**: Call `backend.reset()` to clear state between tests |
| 264 | +3. **Use random ports**: When running tests in parallel, use random port assignments |
| 265 | +4. **Set appropriate timeouts**: Use reasonable timeout values in wait operations |
| 266 | +5. **Clean up workers**: Always stop workers in finally blocks to prevent resource leaks |
| 267 | + |
| 268 | +### Troubleshooting |
| 269 | + |
| 270 | +#### Connection Errors |
| 271 | + |
| 272 | +If you see connection errors: |
| 273 | + |
| 274 | +- Ensure the backend is started before creating clients/workers |
| 275 | +- Verify the port is not already in use |
| 276 | +- Check that the host address matches the backend port |
| 277 | + |
| 278 | +#### Timeouts |
| 279 | + |
| 280 | +If tests timeout: |
| 281 | + |
| 282 | +- Increase timeout values in `wait_for_orchestration_completion` |
| 283 | +- Check that workers are started and processing work items |
| 284 | +- Verify orchestrators and activities are registered correctly |
| 285 | + |
| 286 | +#### State Not Found |
| 287 | + |
| 288 | +If orchestration state is not found: |
| 289 | + |
| 290 | +- Ensure you're using the correct instance ID |
| 291 | +- Verify the orchestration was successfully scheduled |
| 292 | +- Check that the backend wasn't reset between operations |
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