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/unit/test_drivers.py

@@ -0,0 +1,91 @@
+# 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.
+
+"""Unit tests for Unified Base Device Driver and implementations."""
+
+import pytest
+from unittest.mock import MagicMock
+
+from artemis.drivers.base import KeyCode, ScreenData, SwipeDirection
+from artemis.drivers.mock.mock_driver import MockDeviceDriver
+from artemis.drivers.android.adb_driver import AndroidAdbDriver
+
+
+@pytest.mark.asyncio
+async def test_mock_driver_actions():
+    """Verify MockDeviceDriver records and performs all core actions."""
+    driver = MockDeviceDriver(device_id="test-mock", width=1080, height=2400)
+    assert driver.device_id == "test-mock"
+    assert driver.screen_size == (1080, 2400)
+
+    # 1. Screen data
+    screen_data = await driver.get_screen_data()
+    assert isinstance(screen_data, ScreenData)
+    assert screen_data.width == 1080
+    assert screen_data.height == 2400
+    assert screen_data.screenshot_base64 is not None
+
+    # 2. Tap
+    assert await driver.tap(500, 1000) is True
+    assert driver.action_history[-1]["action"] == "tap"
+    assert driver.action_history[-1]["x"] == 500
+
+    # 3. Swipe
+    assert await driver.swipe(100, 200, 300, 400) is True
+    assert driver.action_history[-1]["action"] == "swipe"
+
+    # 4. Swipe direction
+    assert await driver.swipe_direction(SwipeDirection.UP) is True
+    assert driver.action_history[-1]["direction"] == "up"
+
+    # 5. Input text
+    assert await driver.input_text("Hello Artemis") is True
+    assert driver.action_history[-1]["text"] == "Hello Artemis"
+
+    # 6. Press key
+    assert await driver.press_key(KeyCode.HOME) is True
+    assert driver.action_history[-1]["key"] == "home"
+
+    # 7. App lifecycle
+    assert await driver.launch_app("com.android.settings") is True
+    assert await driver.get_current_package() == "com.android.settings"
+    assert await driver.stop_app("com.android.settings") is True
+
+
+@pytest.mark.asyncio
+async def test_android_driver_with_mock_adb():
+    """Verify AndroidAdbDriver formats shell commands properly."""
+    mock_adb_client = MagicMock()
+    mock_adb_device = MagicMock()
+    mock_adb_client.device.return_value = mock_adb_device
+
+    driver = AndroidAdbDriver(
+        device_id="emulator-5554",
+        adb_client=mock_adb_client,
+        width=1080,
+        height=2400,
+    )
+
+    # Test tap
+    await driver.tap(540, 1200)
+    mock_adb_device.shell.assert_called_with("input tap 540 1200")
+
+    # Test multi-tap
+    await driver.tap(540, 1200, times=3, delay_ms=100)
+    expected_multi = "input tap 540 1200 && sleep 0.100 && input tap 540 1200 && sleep 0.100 && input tap 540 1200"
+    mock_adb_device.shell.assert_called_with(expected_multi)
+
+    # Test press key
+    await driver.press_key(KeyCode.BACK)
+    mock_adb_device.shell.assert_called_with("input keyevent 4")