Exploring test application: IronPython (2)

We demonstrated how to run a .NET application from IronPython in the previous part. However, we couldn't control it while it was running. The solution for this problem is to run the tested application in a separate thread. Thus we will be able to enter commands in IronPython console while the tested application is running. Here is a snippet from the source:

import clr
clr.AddReference('System')
clr.AddReference("System.Windows.Forms")
from System import *
from System.Reflection import *
from System.Threading import *
from System.Windows.Forms import Application
from time import sleep

def RunMeCallBack(var):
    global App
    asm = Assembly.LoadFrom('GUIAT_PoC.exe')
    asm_type = asm.GetType('GUIAT_PoC.frmGUIAT')
    App = Activator.CreateInstance(asm_type)
    Application.Run(App)

App = None
ThreadPool.QueueUserWorkItem(WaitCallback(RunMeCallBack))
while not App:
    sleep(0.2)

The RunMeCallBack function starts the tested application the same way as we showed in the previous part. We create an independent thread and run this function in it so it does not block the console. The thread finishes its work when the tested application terminates (the main form of the application is closed) or when the console is closed.

The important part is line

App = Activator.CreateInstance(asm_type)

Here we remember the instance of the main form in the variable App. We have access to the whole application thanks to the App variable! The while cycle at the end ensures waiting until the App variable is not None. Which only happens when our tested application is up and running.

The App variable is our Holy Grail. Let's explore what is inside:

>>> App
<GUIAT_PoC.frmGUIAT object at 0x000000000000002B
[GUIAT_PoC.frmGUIAT, Text: GUIAT - Proof of Concept]>
>>> App.Text
'GUIAT - Proof of Concept'

Basically, we have access to all public properties and methods. Try dir(App) and you'll see. With a trick, we can even access private properties and methods (using the power of reflection).

To find what components are on the main form, iterate through the Controls collection:

>>> for c in App.Controls:
...   print c.Name, c.GetType()
...
btnAddItem System.Windows.Forms.Button
lblNewItem System.Windows.Forms.Label
txtNewItem System.Windows.Forms.TextBox
lbxItems System.Windows.Forms.ListBox
btnQuit System.Windows.Forms.Button

To find out what text is in the text box, try the following:

>>> App.Controls[2].Text
''

Now, write something directly into the text box in the tested application and call the statement again:

>>> App.Controls[2].Text
'something'

Cool, isn't it? ;-)

Next time, I show you how to simulate user interaction programatically - how to send a text or click to the tested application.