The ActiveX dll can be debugged using test container. It is a in-built tool with VC++, Visual Studio IDE. we can set the debug environment in order to use this. In the project properties, go to Debug section, then select the "command" property and set the value as test container from the drop down list. so, when the application is build and run, Test Container application is invoked and we can add the dll component from a avalable list of components. once selected and added in the container, the GUI part is it will be like a box, but the methods can be invoked and tested for functionality.
This is one way for testing using Test Container tool.
If the component is web based, then In project properties->Debug Section set the value to Internet Explorer for "command" property. once it is set and run, the build will be made and the Internet explorer will be opened with blank url. enter the url of the page where ActiveX component is used. this will opens the component in debug Mode. Before starting this, let us see the environment. the ActiveX component wil be installed for the first time in client system, or else when the page is opened the object will be downloaded and installed in the location as mentioned by the devoloper. once it is installed, it will used for succesive calls of the same page, untill client uninstalls the control. Before stating the debug process, the newly build dll and the corresponding pdb file has to be placed in the location where the application installed the component while it is rendered. Now the enviro is set and redy to work, Run the project, it opens the url. place the debug point wherever needed, enter the required page url in th eopened browser and it stops when the debug point reaches.
1. Set the Project property for Debug section->Command to Iexplore.exe
2. Build the component.
3. After successful build copy the dll and correspoding pdb file in the Component installed location.
4. Place the debug points as required.
5. Run the application, it stops at the Break point.