chore: import upstream snapshot with attribution

tests/trainer/test_trainer_dev.py

@@ -0,0 +1,53 @@
+# Copyright (c) Microsoft. All rights reserved.
+
+"""Tests for Trainer.dev requirements."""
+
+from __future__ import annotations
+
+from typing import Any
+
+import pytest
+
+from agentlightning.algorithm import Algorithm, Baseline
+from agentlightning.execution.base import ExecutionStrategy
+from agentlightning.litagent import LitAgent
+from agentlightning.trainer import Trainer
+
+
+class DummyStrategy(ExecutionStrategy):
+    """Execution strategy that only records invocation."""
+
+    def __init__(self) -> None:
+        self.called = False
+
+    def execute(self, algorithm_bundle, runner_bundle, store) -> None:  # type: ignore[override]
+        self.called = True
+
+
+class DummyAgent(LitAgent[Any]):
+    """Minimal agent for exercising Trainer.dev."""
+
+
+class SlowAlgorithm(Algorithm):
+    """Algorithm that does not qualify as FastAlgorithm."""
+
+    def run(self, train_dataset=None, val_dataset=None):  # type: ignore[override]
+        return None
+
+
+def test_dev_requires_fast_algorithm() -> None:
+    trainer = Trainer(strategy=DummyStrategy(), algorithm=SlowAlgorithm())
+    agent = DummyAgent()
+
+    with pytest.raises(TypeError):
+        trainer.dev(agent)
+
+
+def test_dev_allows_fast_algorithm() -> None:
+    strategy = DummyStrategy()
+    trainer = Trainer(strategy=strategy, algorithm=Baseline())
+    agent = DummyAgent()
+
+    trainer.dev(agent)
+
+    assert strategy.called is True