Making a sub-process attachable

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Scenario

An application is started as a sub-process and should be automated without hooking into the parent process or modifications of the startup mechanism in the parent process.

For example, a desktop application is started by sending a HTTP request to a Web Service, which is out of Squish’ scope. To avoid any changes to the way the Web Service starts the application, a special approach can be used, which makes the desktop application attachable by Squish.

Overview

An application can be started with the command-line tools startaut (Qt), startwinaut (native Windows) or startjavaaut (Java). Squish can attach to an application started this way, although it did not start the application directly. This approach can be used to hook into the sub-process in the scenario described above without modifications of the startup mechanism:

To make sure that your application is started in an attachable state, a dummy executable with the filename of the sub-process .exe file has to be created. The dummy executable will start the original sub-process .exe file that has been renamed. The dummy executable makes use of startaut, startwinaut or startjavaaut internally, allowing Squish to attach to the application.

Whenever your application is started, this will be done through the dummy executable, making the approach of attaching transparent to the parent process.

Limitations

The approach explained below (rename original sub-process binary file and replace it by a shell script or dummy application that invokes the sub-process binary in a way that Squish can then attach to it) is not suitable for all cases.

Cases where it will probably not work:

Example #1

Step 1: Rename the sub-process’ .exe file

Rename the sub-process’ .exe file by adding an underscore to its filename. For example, if the executable has the name sub_process.exe, rename it to _sub_process.exe.

Step 2: Set environment variable for the attach command

The dummy application we will create in the next step depends on the environment variable SQUISH_ATTACH_CMD. This variable has to be set to the attach command startaut, startwinaut or startjavaaut and its command-line arguments.

For example, to start a Qt application with C:\Squish\bin\startaut that Squish can attach to via port 4711, SQUISH_ATTACH_CMD would be set to the value

"C:\Squish\bin\startaut --port=4711"

Step 3: Create a dummy application that starts the AUT in an attachable state

Create a dummy application with the original filename of the sub-process .exe file (e.g. sub_process.exe) and place it in the folder of the sub-process .exe file to replace the original executable. The dummy application will start the original executable _my_aut.exe using the command that we defined in the environment variable SQUISH_ATTACH_CMD:

#include "stdafx.h"
#include <windows.h>
#include <string>
 
int wmain( int argc, wchar_t *argv[ ], wchar_t *envp[ ] )
{
    STARTUPINFO si;
    PROCESS_INFORMATION pi;
    ZeroMemory( &si, sizeof(si) );
    si.cb = sizeof(si);
    ZeroMemory( &pi, sizeof(pi) );

    // Environment variable with attach command, e.g. "C:\Squish\startaut.exe --port=4711"
    std::wstring cmd = _tgetenv(L"SQUISH_ATTACH_CMD");
    cmd.append(L" _");
    cmd.append(argv[0]);

    std::wstring cmdLine = L"";

    CreateProcess(NULL,
        (LPTSTR)cmd.c_str(),
        NULL,
        NULL,
        FALSE,
        0,
        NULL,
        NULL,
        &si,
        &pi );
    return 0;
}

Step 4: Register and configure an &ldquo;Attachable AUT&rdquo;

To register the “Attachable AUT” and use it in the Squish IDE for recording and playback, please refer to the instructions for the toolkit your application uses:

Example #2

Step 1: Rename the sub-process&rsquo; .exe file executable

Rename the sub-process’ .exe file executable by adding an underscore to its filename. For example, if the executable has the name sub_process.exe, rename it to \sub_process_.exe.

Step 2 - for Windows: Download and configure dummy application

Download and extract the “dummy” application starter-latest.zip .

Copy starter.exe into the folder with the (renamed) original filename of the AUT and rename it to the original file name (e.g. sub_process.exe).

Copy starter.exe.bat_qt_subprocess into the folder with the (renamed) original filename of the sub-process .exe file and rename it to the original file name, and append .bat to the name (e.g. sub_process.exe.bat)

With this in place, the (renamed) dummy application (starter.exe, now sub_process.exe) will start sub_process.exe.bat, and that in turn will start the original (renamed) executable through startaut.

Note that by default the sub-process will be made attachable on TCP port 4444. You can alter this in the above .bat file, or you can define the environment variable SQUISH_ATTACHABLE_PORT and assign the desired port value to it (in cmd.exe: set SQUISH_ATTACHABLE_PORT=5555).

Step 2 - for Unix: Use a shell script as dummy application

Create a shell script in the same folder as the renamed original .exe file and call it sub_process.exe.

In this shell script start your application via startaut:

#! /bin/sh

"$SQUISH_PREFIX/bin/startaut" --port=4444 ./sub_process.exe_
sub_process.exe

Step 3: Register and configure an &ldquo;Attachable AUT&rdquo;

To register the “Attachable AUT” and use it in the Squish IDE for recording and playback, please refer to the instructions for the toolkit your application uses: