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/tools/outputter/test_outputter_tools.py

@@ -0,0 +1,61 @@
+# 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 artemis.agents.outputter.tools import (
+    get_search_history_tool,
+    get_step_details_tool,
+    get_step_screenshot_tool,
+)
+from artemis.context import ArtemisContext
+import pytest
+
+
+@pytest.fixture
+def history_steps(artemis_context: ArtemisContext):
+    if artemis_context.data_engine:
+        return artemis_context.data_engine.get_agent_friendly_steps()
+    return []
+
+
+def test_get_step_details_tool(history_steps):
+    """Test get_step_details_tool to ensure it runs without errors."""
+    tool = get_step_details_tool(history_steps)
+    result = tool.invoke({"start_step": 1, "end_step": 5})
+
+    assert isinstance(result, str)
+    assert len(result) > 0
+
+
+def test_get_step_screenshot_tool(artemis_context: ArtemisContext, history_steps):
+    """Test get_step_screenshot_tool to ensure it handles requests gracefully."""
+    tool = get_step_screenshot_tool(artemis_context, history_steps)
+
+    result = tool.invoke({"step_number": 1})
+
+    if isinstance(result, list):
+        assert len(result) == 2
+        assert result[0]["type"] == "text"
+        assert result[1]["type"] == "image_url"
+    else:
+        assert isinstance(result, str)
+        assert len(result) > 0
+
+
+def test_get_search_history_tool(artemis_context: ArtemisContext):
+    """Test get_search_history_tool to ensure it can search through history."""
+    tool = get_search_history_tool(artemis_context)
+    result = tool.invoke({"query": "test"})
+
+    assert isinstance(result, str)
+    assert len(result) > 0