test: add comprehensive unit, integration, and e2e test suites

Introduce complete test coverage for the ARTEMIS platform across multiple layers:
Unit tests: Add tests for agent nodes (Planner, Operator, Validator, Diagnoser, FlashRunner, Explorer), tools, utils (OCR/XML fusion, UI hierarchy), and data engine.
Integration tests: Add live tool verification, reactive runner, IME, and standalone workflow tests.
E2E tests: Add end-to-end scenario tests for media playback and failure recovery flows.
Fixtures & mocks: Add mock inputs (audio, video, screenshot) and test utilities.

tests/integration/test_reactive_runner_integration.py

@@ -0,0 +1,45 @@
+# Copyright 2026 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Integration tests for ReactiveRunner and Pipeline."""
+
+import pytest
+from artemis.core.context import ExecutionContext
+from artemis.core.state import ExecutionStatus
+from artemis.drivers.mock.mock_driver import MockDeviceDriver
+from artemis.engine.pipeline import Pipeline
+from artemis.engine.reactive_runner import ReactiveRunner
+
+
+@pytest.mark.asyncio
+async def test_reactive_runner_execution():
+    """Verify ReactiveRunner executes workflow cycles on mock driver."""
+    ctx = ExecutionContext(task_goal="Turn on Bluetooth in Settings", device_id="test-emulator")
+    driver = MockDeviceDriver(device_id="test-emulator")
+
+    runner = ReactiveRunner(ctx=ctx, driver=driver)
+    state = await runner.run(max_turns=5)
+
+    assert state.status == ExecutionStatus.SUCCESS
+    assert state.current_turn >= 1
+    assert len(state.steps) >= 1
+    assert state.steps[0].action_name == "wait_for_delay"
+
+
+@pytest.mark.asyncio
+async def test_pipeline_dispatch():
+    """Verify Pipeline executes with default mock driver."""
+    state = await Pipeline.execute(goal="Open YouTube and play video", profile="flash")
+    assert state.status == ExecutionStatus.SUCCESS
+    assert state.task_goal == "Open YouTube and play video"