feat: Set up comprehensive Python testing infrastructure

.gitignore

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+# Testing
+.pytest_cache/
+.coverage
+htmlcov/
+coverage.xml
+.tox/
+.nox/
+
+# Claude settings
+.claude/*
+
+# Python
+__pycache__/
+*.py[cod]
+*$py.class
+*.so
+.Python
+build/
+develop-eggs/
+dist/
+downloads/
+eggs/
+.eggs/
+lib/
+lib64/
+parts/
+sdist/
+var/
+wheels/
+share/python-wheels/
+*.egg-info/
+.installed.cfg
+*.egg
+MANIFEST
+
+# Virtual environments
+.env
+.venv
+env/
+venv/
+ENV/
+env.bak/
+venv.bak/
+
+# IDEs and editors
+.vscode/
+.idea/
+*.swp
+*.swo
+*~
+.DS_Store
+Thumbs.db
+
+# Jupyter Notebook
+.ipynb_checkpoints
+
+# IPython
+profile_default/
+ipython_config.py
+
+# pyenv
+.python-version
+
+# pipenv
+Pipfile.lock
+
+# Celery
+celerybeat-schedule
+celerybeat.pid
+
+# SageMath parsed files
+*.sage.py
+
+# Environments
+.env
+.env.local
+.env.development.local
+.env.test.local
+.env.production.local
+
+# mypy
+.mypy_cache/
+.dmypy.json
+dmypy.json
+
+# Pyre type checker
+.pyre/
+
+# pytype static type analyzer
+.pytype/
+
+# Cython debug symbols
+cython_debug/
+
+# Temporary files
+*.tmp
+*.temp
+.tmp/
+temp/
+
+# Logs
+*.log
+logs/

pyproject.toml

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+[tool.poetry]
+name = "extra-image-list"
+version = "0.2.9"
+description = "An alternative image list for UV/Image Editor in Blender"
+authors = ["Miki (meshlogic) <meshlogic@example.com>", "Rombout Versluijs <rombout@example.com>"]
+readme = "README.md"
+license = "GPL-3.0"
+homepage = "https://github.com/schroef/Extra-Image-List"
+repository = "https://github.com/schroef/Extra-Image-List"
+keywords = ["blender", "addon", "uv", "image", "editor"]
+classifiers = [
+    "Development Status :: 4 - Beta",
+    "Intended Audience :: End Users/Desktop",
+    "License :: OSI Approved :: GNU General Public License v3 (GPLv3)",
+    "Programming Language :: Python :: 3",
+    "Topic :: Multimedia :: Graphics :: 3D Modeling",
+    "Topic :: Software Development :: Libraries :: Python Modules",
+]
+packages = [{include = "*.py", from = "."}]
+package-mode = false
+
+[tool.poetry.dependencies]
+python = "^3.7"
+
+[tool.poetry.group.test.dependencies]
+pytest = "^7.0.0"
+pytest-cov = "^4.0.0"
+pytest-mock = "^3.10.0"
+
+# Using group dependencies for testing instead of scripts
+# Run tests with: poetry run pytest
+
+[build-system]
+requires = ["poetry-core"]
+build-backend = "poetry.core.masonry.api"
+
+[tool.pytest.ini_options]
+testpaths = ["tests"]
+python_files = ["test_*.py", "*_test.py"]
+python_classes = ["Test*"]
+python_functions = ["test_*"]
+addopts = [
+    "--strict-markers",
+    "--strict-config",
+    "--verbose",
+    "--cov=.",
+    "--cov-report=term-missing",
+    "--cov-report=html:htmlcov",
+    "--cov-report=xml:coverage.xml",
+    "--cov-fail-under=80",
+]
+markers = [
+    "unit: marks tests as unit tests (fast, isolated)",
+    "integration: marks tests as integration tests (slower, with dependencies)",
+    "slow: marks tests as slow (deselect with '-m \"not slow\"')",
+]
+
+[tool.coverage.run]
+source = ["."]
+omit = [
+    "tests/*",
+    "htmlcov/*",
+    ".venv/*",
+    "venv/*",
+    "*.egg-info/*",
+    "build/*",
+    "dist/*",
+    ".pytest_cache/*",
+    ".coverage",
+    "setup.py",
+    "__init__.py",
+]
+branch = true
+
+[tool.coverage.report]
+exclude_lines = [
+    "pragma: no cover",
+    "def __repr__",
+    "if self.debug:",
+    "if settings.DEBUG",
+    "raise AssertionError",
+    "raise NotImplementedError",
+    "if 0:",
+    "if __name__ == .__main__.:",
+    "class .*\\bProtocol\\):",
+    "@(abc\\.)?abstractmethod",
+]
+show_missing = true
+precision = 2
+
+[tool.coverage.html]
+directory = "htmlcov"
+
+[tool.coverage.xml]
+output = "coverage.xml"

tests/conftest.py

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+import os
+import tempfile
+import pytest
+from pathlib import Path
+from unittest.mock import Mock, MagicMock
+
+
+@pytest.fixture
+def temp_dir():
+    """Create a temporary directory for tests that gets cleaned up automatically."""
+    with tempfile.TemporaryDirectory() as tmp_dir:
+        yield Path(tmp_dir)
+
+
+@pytest.fixture
+def temp_file():
+    """Create a temporary file for tests that gets cleaned up automatically."""
+    with tempfile.NamedTemporaryFile(mode='w+', delete=False) as tmp_file:
+        yield Path(tmp_file.name)
+
+    # Clean up the file after the test
+    try:
+        os.unlink(tmp_file.name)
+    except FileNotFoundError:
+        pass
+
+
+@pytest.fixture
+def mock_bpy():
+    """Mock the bpy module for testing Blender addon functionality."""
+    mock_bpy = MagicMock()
+
+    # Mock common bpy structures
+    mock_bpy.data.images = []
+    mock_bpy.types.Scene = MagicMock()
+    mock_bpy.props.EnumProperty = MagicMock()
+    mock_bpy.props.StringProperty = MagicMock()
+    mock_bpy.props.BoolProperty = MagicMock()
+    mock_bpy.props.IntProperty = MagicMock()
+    mock_bpy.props.PointerProperty = MagicMock()
+    mock_bpy.utils.register_class = MagicMock()
+    mock_bpy.utils.unregister_class = MagicMock()
+    mock_bpy.context.scene = MagicMock()
+    mock_bpy.context.space_data = MagicMock()
+    mock_bpy.context.active_object = MagicMock()
+    mock_bpy.app.handlers.depsgraph_update_post = MagicMock()
+
+    return mock_bpy
+
+
+@pytest.fixture
+def mock_blender_context():
+    """Mock Blender context for testing."""
+    context = MagicMock()
+    context.scene = MagicMock()
+    context.space_data = MagicMock()
+    context.space_data.image = None
+    context.active_object = MagicMock()
+    context.active_object.type = 'MESH'
+    context.active_object.active_material = MagicMock()
+    context.screen.areas = []
+
+    return context
+
+
+@pytest.fixture
+def mock_image():
+    """Mock Blender image datablock for testing."""
+    image = MagicMock()
+    image.name = "test_image.png"
+    image.filepath = "/path/to/test_image.png"
+    image.source = 'FILE'
+    image.has_data = True
+    image.users = 1
+    image.use_fake_user = False
+    image.packed_file = None
+    image.size = [1024, 1024]
+    image.depth = 32
+
+    return image
+
+
+@pytest.fixture
+def sample_image_list():
+    """Create a sample list of mock images for testing."""
+    images = []
+    for i in range(5):
+        image = MagicMock()
+        image.name = f"image_{i}.png"
+        image.filepath = f"/path/to/image_{i}.png"
+        image.source = 'FILE'
+        image.has_data = True
+        image.users = 1 if i < 3 else 0  # First 3 have users, last 2 don't
+        image.use_fake_user = i == 4  # Last one is fake user
+        image.packed_file = None if i != 2 else MagicMock()  # Third one is packed
+        image.size = [512 * (i + 1), 512 * (i + 1)]
+        image.depth = 24
+        images.append(image)
+
+    return images
+
+
+@pytest.fixture
+def mock_addon_preferences():
+    """Mock addon preferences for testing."""
+    prefs = MagicMock()
+    prefs.style = 'PREVIEW'
+    prefs.rows = 4
+    prefs.cols = 6
+    prefs.clean_enabled = False
+    prefs.clear_mode = 'NO USERS'
+    prefs.info = False
+    prefs.image_id = 0
+
+    return prefs
+
+
+@pytest.fixture(autouse=True)
+def reset_environment():
+    """Reset environment variables and state before each test."""
+    # Store original environment
+    original_env = dict(os.environ)
+
+    yield
+
+    # Restore original environment
+    os.environ.clear()
+    os.environ.update(original_env)
+
+
+@pytest.fixture
+def sample_config():
+    """Provide sample configuration data for tests."""
+    return {
+        "preview_rows": 4,
+        "preview_cols": 6,
+        "default_style": "PREVIEW",
+        "clean_enabled": False,
+        "show_info": True,
+    }
+
+
+class MockBlenderOperator:
+    """Mock Blender operator for testing."""
+
+    def __init__(self):
+        self.bl_idname = "test.operator"
+        self.bl_label = "Test Operator"
+        self.bl_description = "Test operator description"
+
+    def execute(self, context):
+        return {'FINISHED'}
+
+    @classmethod
+    def poll(cls, context):
+        return True
+
+
+@pytest.fixture
+def mock_operator():
+    """Provide a mock Blender operator for testing."""
+    return MockBlenderOperator()
+
+
+@pytest.fixture
+def isolated_filesystem(temp_dir):
+    """Change to a temporary directory for the test and restore afterwards."""
+    original_cwd = os.getcwd()
+    os.chdir(temp_dir)
+
+    yield temp_dir
+
+    os.chdir(original_cwd)