revit-pytest

name

revit-pytest

description

Create and run CAD/BIM API tests using pytest via RevitDevTool Named Pipe bridge. Use when writing new pytest test files for Revit/AutoCAD/Civil3D API, adding test fixtures for host documents/elements, running tests against a live host instance, setting up conftest.py with PEP 723 dependencies, or asking "how do I test Revit API with pytest". Covers test structure, fixtures, lazy imports, transactions, auto-rollback, dependency injection, and CLI options.

Host API Testing with pytest

How It Works

Local pytest (collect) → Named Pipe → Host (PytestRunner.py) → Results → Local pytest (report)

Tests are collected locally by pytest, then executed remotely inside a live host process (Revit, AutoCAD, Civil3D, etc.) via JSON-RPC over Named Pipes. Results (pass/fail/skip, stdout, tracebacks) return to the local pytest session.

1. Project Setup

# Create project with uv (recommended)
uv init my-revit-tests
cd my-revit-tests
uv add revitdevtool_pytest

Or with pixi:

pixi init --format pyproject my-revit-tests
cd my-revit-tests
pixi add --pypi revitdevtool_pytest

2. Configure pyproject.toml

Minimal config — only host_version is required:

[tool.pytest.ini_options]
host_version = "2025"

Full options:

[tool.pytest.ini_options]
host_name = "revit"
host_version = "2025"
host_launch = false
host_timeout = "60"
host_launch_timeout = "180"

Option	Default	Description
host_name	"revit"	Host application (revit, autocad, civil3d, plant3d, etc.)
host_version	—	Host version (e.g. 2025, 8.0). Required when host_launch = true.
host_launch	false	Force-launch a new host instance (ignores existing).
host_timeout	"60"	Per-test execution timeout (seconds).
host_launch_timeout	"120"	Seconds to wait for host to start.
host_pipe	—	Explicit pipe name (bypass auto-discovery).

3. Write conftest.py

# /// script
# dependencies = [
#   "numpy>=2.0",
# ]
# ///
"""PEP 723 dependencies above are auto-installed by RevitDevTool."""

import pytest

@pytest.fixture(scope="session")
def revit_uiapp():
    return __revit__  # noqa: F821

@pytest.fixture(scope="session")
def revit_app(revit_uiapp):
    return revit_uiapp.Application

@pytest.fixture(scope="session")
def revit_doc(revit_uiapp):
    return revit_uiapp.ActiveUIDocument.Document

@pytest.fixture
def revit_auto_rollback():
    """Start undo tracking, revert after test."""
    from RevitDevTool.Core import RevitTransactionService
    RevitTransactionService.StartChanges()
    try:
        yield RevitTransactionService
    finally:
        RevitTransactionService.RevertChanges()

4. Write Tests

Critical rule: All host/.NET imports MUST be inside function bodies.

def test_active_view(revit_doc):
    view = revit_doc.ActiveView
    print(f"Active View: {view.Name}")
    assert view is not None

def test_wall_count(revit_doc):
    from Autodesk.Revit.DB import FilteredElementCollector, BuiltInCategory

    walls = list(
        FilteredElementCollector(revit_doc)
        .OfCategory(BuiltInCategory.OST_Walls)
        .WhereElementIsNotElementType()
    )
    assert len(walls) > 0

def test_create_and_rollback(revit_doc, revit_auto_rollback):
    from Autodesk.Revit.DB import Transaction
    with Transaction(revit_doc, "Test") as t:
        t.Start()
        # modify model...
        t.Commit()
    # revit_auto_rollback reverts all changes after test

5. Run Tests

# Preferred: uv run
uv run pytest -v

# Or pixi:
pixi run pytest -v

# Or activate venv manually:
& ".venv\Scripts\pytest.exe" -v

# Specific test:
pytest tests/test_walls.py::test_wall_count -v

# Override version for one run:
pytest --host-version=2026 -v

# Force new host instance:
pytest --host-launch --host-version=2025 -v

# Target AutoCAD:
pytest --host autocad --host-version=2026 -v

# Target Civil 3D:
pytest --host civil3d --host-version=2026 -v

Key Behaviors

Print output

print() inside tests is automatically captured and displayed in terminal output for both passing and failing tests. No extra flags needed.

Connection

• Default: plugin scans for running host matching host_version via Named Pipe ({Host}_{Version}_{PID}, e.g. Revit_2025_12345, Rhino_8.0_9999)
• host_launch = true: spawns new host, waits for its specific PID pipe, ignores existing instances
• host_pipe = "Revit_2025_12345": connect to exact pipe (skip discovery). Any {Host}_{Version}_{PID} pipe works.

Execution context

• Tests run on the host's main thread sequentially
• __revit__ (Revit) or equivalent builtins are injected by host setup scripts (always access via fixtures)
• --capture=sys is used internally (fd capture doesn't work in embedded Python.NET)

Common Mistakes

Mistake	Fix
Import host API at module level	Move to inside function body
Use __revit__ directly without noqa	Use revit_uiapp fixture
Run bare pytest without venv	Use uv run pytest or activate venv
Expect host_launch to reuse instances	It always launches NEW (use default for reuse)
Missing host_version with host_launch	Set host_version in config or CLI