[Sub] Write Coordinator Unit Tests

[switch180]

Parent Issue: #4 Zero Test Coverage

Objective

Create comprehensive unit tests for the RiverLinkDataUpdateCoordinator covering data parsing, mode detection, and stream mapping.

Test Coverage Areas

Data Parsing Tests

• test_parse_device_data - Overall parsing logic
• test_parse_receiver - Receiver data extraction
• test_parse_transmitter - Transmitter data extraction
• test_stream_map_building - Multicast address mapping

Video Mode Detection Tests

• test_extract_video_mode_genlock - Genlock mode detection
• test_extract_video_mode_genlock_scaling - Scaling mode
• test_extract_video_mode_fastswitch - Fast switch modes
• test_extract_video_mode_wall - Video wall modes
• test_extract_video_mode_multiview - Multiview detection

Resolution Tests

• test_find_resolution_preset - Preset matching
• test_custom_resolution - Non-standard resolutions
• test_pending_resolution_persistence - Pending state handling

Signal Extraction Tests

• test_extract_video_signal - Video signal info
• test_extract_hdcp_info - HDCP status
• test_extract_ip_address - Network info

Error Scenarios

• test_missing_devices - Empty device list
• test_malformed_response - Invalid API data
• test_missing_nodes - Incomplete device info

Mock Strategy

# Use fixture files for API responses
@pytest.fixture
def mock_api_response():
    with open('tests/fixtures/api_responses.json') as f:
        return json.load(f)

Target Coverage

• Goal: 85%+ line coverage for coordinator.py
• Focus: Parsing logic and edge cases

References

• File: custom_components/riverlink/coordinator.py
• Sample Data: get-all-devices-actual-response.json
• Parent Issue: Zero Test Coverage - Critical Testing Infrastructure Gap #4

Priority

🔴 High - Critical parsing logic