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/tools/test_log_utils.py

@@ -0,0 +1,116 @@
+# 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.
+
+from datetime import datetime
+from unittest.mock import Mock, patch
+from artemis.context import ArtemisContext
+from artemis.tools.mobile.log_utils import fetch_and_filter_logs
+import pytest
+
+
+@pytest.fixture
+def mock_context():
+    ctx = Mock(spec=ArtemisContext)
+    ctx.data_engine = Mock()
+    ctx.data_engine.session_start_time = 1700000000.0  # Example timestamp
+    return ctx
+
+
+@pytest.fixture
+def mock_device():
+    return Mock()
+
+
+@patch("artemis.tools.mobile.log_utils.get_adb_device")
+def test_fetch_and_filter_logs_basic(mock_get_adb_device, mock_context, mock_device):
+    mock_get_adb_device.return_value = mock_device
+    mock_device.shell.return_value = "line 1\nline 2\n"
+
+    result = fetch_and_filter_logs(mock_context, lines=10)
+
+    mock_device.shell.assert_called_once_with("logcat -v threadtime -t 10")
+    assert result == "line 1\nline 2\n"
+
+
+@patch("artemis.tools.mobile.log_utils.get_adb_device")
+@patch("artemis.tools.mobile.log_utils.resolve_time")
+def test_fetch_and_filter_logs_since_time_success(
+    mock_resolve_time, mock_get_adb_device, mock_context, mock_device
+):
+    mock_get_adb_device.return_value = mock_device
+    since_dt = datetime(datetime.now().year, 5, 3, 11, 11, 11, 111000)
+    mock_resolve_time.side_effect = [
+        ("05-03 11:11:11.111", since_dt),  # for since_time
+        (None, None),  # for until_time
+    ]
+
+    mock_device.shell.return_value = "05-03 11:11:12.000 line 1\n05-03 11:11:13.000 line 2\n"
+
+    result = fetch_and_filter_logs(mock_context, since_time="05-03 11:11:11.111")
+
+    mock_device.shell.assert_called_once_with('logcat -v threadtime -t "05-03 11:11:11.111"')
+    assert "line 1" in result
+    assert "line 2" in result
+
+
+@patch("artemis.tools.mobile.log_utils.get_adb_device")
+@patch("artemis.tools.mobile.log_utils.resolve_time")
+def test_fetch_and_filter_logs_since_time_fallback(
+    mock_resolve_time, mock_get_adb_device, mock_context, mock_device
+):
+    mock_get_adb_device.return_value = mock_device
+    current_year = datetime.now().year
+    since_dt = datetime(current_year, 5, 4, 12, 0, 0)
+    mock_resolve_time.side_effect = [
+        ("05-04 12:00:00.000", since_dt),  # for since_time
+        (None, None),  # for until_time
+    ]
+
+    # Direct fetch fails
+    mock_device.shell.side_effect = [
+        Exception("logcat failed"),  # first call to direct fetch
+        "05-04 11:59:00.000 line old\n05-04 12:00:01.000 line new\n",  # second call (fallback)
+    ]
+
+    result = fetch_and_filter_logs(mock_context, lines=100, since_time="05-04 12:00:00.000")
+
+    assert mock_device.shell.call_count == 2
+    mock_device.shell.assert_any_call('logcat -v threadtime -t "05-04 12:00:00.000"')
+    mock_device.shell.assert_any_call("logcat -v threadtime -t 100")
+
+    # Should filter out "line old" because it's before since_dt
+    assert "line old" not in result
+    assert "line new" in result
+
+
+@patch("artemis.tools.mobile.log_utils.get_adb_device")
+@patch("artemis.tools.mobile.log_utils.resolve_time")
+def test_fetch_and_filter_logs_until_time(
+    mock_resolve_time, mock_get_adb_device, mock_context, mock_device
+):
+    mock_get_adb_device.return_value = mock_device
+    current_year = datetime.now().year
+    until_dt = datetime(current_year, 5, 4, 12, 0, 0)
+    mock_resolve_time.side_effect = [
+        (None, None),  # for since_time
+        ("05-04 12:00:00.000", until_dt),  # for until_time
+    ]
+
+    mock_device.shell.return_value = "05-04 11:59:00.000 line old\n05-04 12:00:01.000 line new\n"
+
+    result = fetch_and_filter_logs(mock_context, lines=100, until_time="05-04 12:00:00.000")
+
+    mock_device.shell.assert_called_once_with("logcat -v threadtime -t 100")
+    assert "line old" in result
+    assert "line new" not in result