A testing device for testing a system configured of an application and a set of execution-environment-dependent resources used by the application includes a DI container for injecting one resource set (EUT) into an application for which a test is executed via an application interface, the resource set being a candidate of dependency injection into the application, and a test execution unit that executes a test on the application with the one resource set having been injected therein. When another resource set that is different from the one resource set exists the injection by the DI container and the test by the test execution unit are executed on the other resource set.