Testing

The QtNodes library includes a comprehensive unit test suite built with Catch2.

Test Coverage

The test suite covers the following areas:

Core Functionality (20 test cases, 216 assertions)

  • AbstractGraphModel operations (node CRUD, connections)

  • AbstractGraphModel signal emissions (comprehensive signal testing)

  • DataFlowGraphModel functionality

  • NodeDelegateModelRegistry operations

  • Serialization (save/load JSON)

  • Undo system integration

  • Graphics scene management

  • Connection ID utilities

Data Flow Testing (5 test cases, 46 assertions)

  • Real data transfer between connected nodes using NodeDelegateModel pattern

  • Programmatic and interactive connection creation with data propagation

  • Multiple output connections (one-to-many data distribution)

  • Connection lifecycle testing (creation, data flow, disconnection)

  • Custom node delegate models with embedded widgets and signal handling

Visual UI Interaction Testing (3 test cases, 5 assertions)

  • Node movement and visual positioning

  • Connection creation by dragging between ports

  • Connection disconnection by dragging and deletion

  • Zoom and pan operations

  • Keyboard shortcuts (delete, undo)

  • Context menu interactions

  • Stress testing with rapid mouse movements and UI load

Total: 28 test cases, 267 assertions

Infrastructure

  • Complete AbstractGraphModel test implementation

  • Qt application setup utilities

  • Node delegate stubs for testing

  • UITestHelper namespace for UI interaction simulation

  • Virtual display testing with proper window exposure

  • Clean build system without internal dependencies

Running Tests

From the build directory:

# Build tests
make test_nodes

# Run all tests
./bin/test_nodes

# Run specific test categories
./bin/test_nodes "[core]"        # Core functionality
./bin/test_nodes "[signals]"     # Signal emission tests
./bin/test_nodes "[dataflow]"    # DataFlowGraphModel tests
./bin/test_nodes "[registry]"    # Registry tests
./bin/test_nodes "[serialization]"  # Save/load tests
./bin/test_nodes "[undo]"        # Undo system tests
./bin/test_nodes "[graphics]"    # Graphics tests
./bin/test_nodes "[ui]"          # UI interaction tests
./bin/test_nodes "[visual]"      # Visual UI tests
./bin/test_nodes "[stress]"      # Stress tests

Test Structure

Tests are organized in test/ directory:

test/
├── CMakeLists.txt              # Build configuration
├── include/
│   ├── ApplicationSetup.hpp    # Qt app setup
│   ├── TestGraphModel.hpp      # Test graph model
│   └── TestDataFlowNodes.hpp   # Node delegate stub
└── src/
    ├── TestAbstractGraphModel.cpp
    ├── TestAbstractGraphModelSignals.cpp
    ├── TestDataFlowGraphModel.cpp
    ├── TestNodeDelegateModelRegistry.cpp
    ├── TestBasicGraphicsScene.cpp
    ├── TestConnectionId.cpp
    ├── TestCopyPaste.cpp
    ├── TestCustomPainters.cpp
    ├── TestLoopDetection.cpp
    ├── TestNodeValidation.cpp
    ├── TestSerialization.cpp
    ├── TestUIInteraction.cpp
    ├── TestUndoCommands.cpp
    └── TestZoomFeatures.cpp

Test Categories

Core Tests ([core])

  • AbstractGraphModel basic functionality

  • Connection management

  • Node deletion with connections

  • ConnectionId utilities and edge cases

Signal Tests ([signals])

  • Signal emission verification for all AbstractGraphModel signals

  • Signal spy validation and argument type checking

  • Signal consistency with model state

  • Edge case signal behavior (invalid operations)

  • Complex operation signal ordering

DataFlow Tests ([dataflow])

  • DataFlowGraphModel operations

  • Node creation and validation

  • Connection possibility checks

  • Port bounds validation

Registry Tests ([registry])

  • NodeDelegateModelRegistry functionality

  • Model registration with categories

  • Lambda factory registration

  • Category associations

Serialization Tests ([serialization])

  • DataFlowGraphModel serialization

  • Individual node serialization

  • JSON save/load operations

Undo System Tests ([undo])

  • QUndoStack integration with BasicGraphicsScene

  • Manual undo/redo simulation

  • State tracking

Graphics Tests ([graphics])

  • BasicGraphicsScene functionality

  • Graphics undo/redo support

  • Scene management

UI Interaction Tests ([ui], [visual], [stress])

  • Node movement and visual positioning using UITestHelper namespace

  • Connection creation by dragging between ports

  • Connection disconnection by dragging from ports and deletion of selected connections

  • Zoom and pan operations with mouse wheel and drag

  • Keyboard shortcuts (delete key, Ctrl+Z undo)

  • Context menu interactions (right-click)

  • Stress testing with rapid mouse movements and memory load

  • Virtual display testing with proper window exposure handling

Validation Tests ([validation])

  • NodeValidationState struct functionality

  • NodeProcessingStatus enum values

  • Setting validation and processing status through NodeDelegateModel

  • Integration with DataFlowGraphModel

Custom Painters Tests ([painters])

  • Custom node painter registration

  • Custom connection painter registration

  • Painter replacement behavior

  • Paint method invocation verification

Copy/Paste Tests ([copypaste])

  • Single node copy

  • Multiple node copy with connections

  • Paste operations

  • Duplicate operations (Ctrl+D)

Zoom Tests ([zoom])

  • Scale range configuration

  • zoomFitAll behavior

  • zoomFitSelected behavior

  • scaleChanged signal emission

Loop Detection Tests ([loops])

  • loopsEnabled configuration in AbstractGraphModel

  • DataFlowGraphModel loop prevention

  • Direct self-loop prevention

  • Indirect cycle detection

Key Features

Segfault Resolution: Fixed critical infinite recursion in signal emission that was causing stack overflow crashes during graphics system updates.

API Modernization: Updated from v2.x to v3.x Model-View architecture with proper AbstractGraphModel implementation following QtNodes best practices.

Clean Dependencies: Removed internal header dependencies, using only public APIs for better stability and maintainability.

Signal Emission Testing: Comprehensive verification of all AbstractGraphModel signals using QSignalSpy, ensuring proper signal emission for all operations including node creation/deletion, connection creation/deletion, and node updates.

Comprehensive Coverage: Tests all major functionality including node management, connections, serialization, undo system, and graphics integration.

Port Bounds Validation: Added proper validation in connectionPossible() to ensure port indices are within valid ranges.

Building Tests

Tests are built automatically when BUILD_TESTING is enabled (default).

Prerequisites:

  • Catch2 testing framework

  • Qt6 (or Qt5 with appropriate configuration)

  • CMake 3.8+

Configuration:

# Enable testing (default)
cmake .. -DBUILD_TESTING=ON

# Disable testing
cmake .. -DBUILD_TESTING=OFF

Build:

# Build library and tests
make

# Build only tests
make test_nodes

Test Implementation Details

TestGraphModel: A complete implementation of AbstractGraphModel that provides:

  • Full node and connection management

  • Proper signal emission patterns

  • Serialization support

  • Integration with graphics systems

UITestHelper: A namespace providing utility functions for UI interaction testing:

  • simulateMousePress/Move/Release() - Low-level mouse event simulation

  • simulateMouseDrag() - High-level drag operation simulation

  • waitForUI(ms = 10) - Optimized UI event processing with 10ms default timing

  • Proper Qt event system integration for realistic UI testing

Signal Safety: The test model implements signal emission patterns that prevent infinite recursion between the model and graphics system, following the approach used in examples/simple_graph_model.

Mock Objects: Comprehensive stub implementations for testing without external dependencies, including StubNodeDataModel for node delegate testing.

Troubleshooting

Common Issues:

  • Catch2 not found: Install Catch2 or disable testing with -DBUILD_TESTING=OFF

  • Qt version conflicts: Ensure consistent Qt5/Qt6 usage throughout build

  • Missing test binary: Check that BUILD_TESTING is enabled in CMake configuration

Performance Notes:

  • Tests include Qt application setup overhead

  • Graphics tests may show Qt warnings about runtime directories (these are harmless)

  • UI tests use optimized 10ms timing for consistent performance

  • Full test suite typically completes in under 10 seconds