A litlle late, but here is a solution that I used - I`ve set as build_systems inside sublime project configs.

The example.sublime-project looks like:

{

"folders":

[

{

"path": "/path/to/your/project"

}

],

    "build_systems":

    [

        {

            "name": "Run Tests",

            // activate the specific virtualenv for the project

            "cmd": ["source", "/path/to/your/virtualenv/bin/activate"],

            // now indicates a different folder to run the next cmd

            "working_dir": "/path/to/to/you/django_project",

            // runs the test

            "cmd": ["python", "manage.py", "test"]

        }

    ]

}