#OpenTAP_pytest.md

#OpenTAP_pytest.md

Overview

• This file explores using Python's unit testing framework, PyTest, in conjunction with OpenTAP's Python resources.
• OpenTAP was built using the .NET framework; Python capabilities were later added via the Python.NET library.
• Python.NET is a bridge between Python and .NET platforms, enabling interoperation between the two. This tool allows Python programs to access the .NET Framework and Mono libraries; similarly, it provides .NET applications the ability to utilize Python libraries.

Details

• This demonstration is using Windows 11
• This demonstration is using Python 3.11.3

Simple Python.NET Example

• The following example imports the Common Language Runtime (CLR) module from .NET via Python.NET. Afterward, it constructs a string using the .NET framework then uses that object's built-in length method.

string_dotnet.py

'''
NAME: 
    string_dotnet.py

OVERVIEW: 
    This script explores the use of the Python.NET library in Python.

DETAILS:
    Python.NET is a bridge between Python and .NET platforms, enabling interoperation
    between the two. This tool allows Python programs to access the .NET Framework 
    and Mono libraries; similarly, it provides .NET applications the ability to 
    utilize Python libraries.

    This script imports the Common Language Runtime (CLR) module from .NET.

    The function `string_length(s)` illustrates this interoperation. It constructs a
    string `s` via CLR from .NET, and then returns the length of this string.
'''

import clr
clr.AddReference('System')

from System import String

def string_length(s):
    dotnet_string = String(s)
    return dotnet_string.Length

main.py

'''
NAME: 
    main.py

OVERVIEW: 
    This program is the driver to test `string_dotnet.py`.

DETAILS:
    Expected output is 12. See `string_dotnet.py` for details.

'''

import clr                          
import string_dotnet as dotnet

clr.AddReference("System")
from System import Console

print(dotnet.string_length("Hello World!"));

Output

python main.py
12

Simple PyTest with Python.NET Resources

• Continue using main.py and dotnet_string.py from the Simple Python.NET Example section.
• The following content uses Python's built-in unit testing framework, PyTest, to test our aformentioned files.
• Section successfully demonstrates that we can use PyTest in conjunction with Python.NET.

test_my_dotnet_module.py

# test_string_dotnet.py
import string_dotnet as dotnet

def test_dotnet_string_length():
    assert dotnet.string_length("Hello") == 5
    assert dotnet.string_length("") == 0

Output

python -m pytest test_string_dotnet.py
========================================================= test session starts =========================================================
platform win32 -- Python 3.11.3, pytest-7.3.1, pluggy-1.0.0
rootdir: C:\Users\shawn\OneDrive\Desktop\Demo2\OpenTAP PyTest
collected 1 item

test_string_dotnet.py .                                                                                                          [100%]

========================================================== 1 passed in 0.35s ==========================================================

Simple PyTest with OpenTAP Resources

• Attempting to run PyTest in conjunction with the boiler plate OpenTAP Python project setup.

Filetree

.
├── ...
├── demo/
│   ├── test.py
│   ├── TestInstrument.py
│   └── TestStepExample.py
└── ...

TestStepExample.py

# TestStepExample.py
from opentap import *
from System import Int32
import OpenTap
from .TestInstrument import TestInstrument

@attribute(OpenTap.Display("Test Step Example", "A simple python test step", "demo"))
class TestStepExample (TestStep):
    my_test_instrument = property(TestInstrument).\
        add_attribute(OpenTap.Display(
            "Instrument", "The instrument to use in the step.", "Resources"))

    def __init__(self):
        super(TestStepExample, self).__init__()
    
    def Run(self):
        self.log.Debug("Number of characters: {0}", Int32(self.my_test_instrument.string_length("Hello World!")))

TestInstrument.py

# TestInstrumnet.py
from opentap import *
from System import String
import OpenTap
import clr
clr.AddReference("demo.Api")
from demo.Api import PythonInstrumentApi

@attribute(OpenTap.Display("Test Instrument", "This class implements a shared Python API.", "demo"))
class TestInstrument(Instrument, PythonInstrumentApi):
    def __init__(self):
        "Set up the properties, methods and default values of the instrument."
        super(TestInstrument, self).__init__()
        self.Name = "Test Instrument" 
    
    def string_length(self, s):
        dotnet_string = String(s)
        return dotnet_string.Length

test.py

# test.py
import TestInstrument as dotnet

def test_dotnet_string_length():
    assert dotnet.string_length("Hello") == 5
    assert dotnet.string_length("") == 0

Observations

• PyTest cannot find opentap module.
• Module opentap lives in the default OpenTAP isntallation directory at C:\Program Files\OpenTAP\Packages\Python
• Module opentap is a .NET bridge iteroperating the OpenTAP .NET library so that it can be used by Python.
• I attempted to add the resource into my Python interpert's path but it failed. The module has a dynamically linked library dependencies; I think this is C:\Program Files\OpenTAP\Packages\Python\OpenTap.Python.dll. Adding this file is likely not a practical solution... It could be though if organized properly but may be too large of an undertaking.