Frequently Asked Questions

Who maintains Inferno?

Development of Inferno is led by the Office of the National Coordinator for Health IT and core components are implemented by the MITRE Corporation. External participation and contributions are encouraged and welcome. To learn how to participate, visit the Community page of this site.

Does Inferno use the FHIR TestScript Resource?

Inferno does not currently use the standard FHIR Testscript Resource for describing tests, and instead uses the Inferno Test DSL (Domain Specific Language).

The Inferno Test DSL is designed to enable test writers to create high fidelity simulated test clients that can serve as realistic data exchange partners for FHIR APIs being tested. This allows for comprehensive conformance tests that that have the flexibility to stay within any domain-specific constraints imposed on clients by Implementation Guides. It also enables a higher level of testing automation, as test writers can leverage a full-featured programming language within the tests themselves.

TestScript expresses tests as a linear set of HTTP requests with expectations attached to the request and response. Conformance to an Implementation Guide requires the definition of many separate TestScripts to test various data exchanges defined within the FHIR Implementation Guide. TestScripts can either be used to drive a simulated client to evaluate the conformance of a FHIR API, or to evaluate the conformance of data exchanges created by other clients and servers.

In the base TestScript definition provided by the FHIR specification, only simple client simulators can be implemented using TestScript, as there is no support for conditional requests or looping constructs. TestScripts can be extended using platform-specific extensions to enable higher-fidelity simulated clients, if that is needed to accomplish the test writer’s testing goals. However, using non-standard extensions within TestScripts negates some of the value of TestScript, as scripts are no longer portable between testing systems that have not implemented all of the same extensions. Additionally, extensive use of extensions to recreate features of a fully featured programming language would result in a programming language that is expressed within the FHIR data model, which would be counter-productive.

The Inferno approach is to describe tests within a full-featured programming environment such that test developers can create low or high fidelity simulated clients using the Ruby programming language. The testing DSL provided attempts to make simple tests written in Inferno to be approximately as easy to understand as tests written in TestScript, but is designed to make it much easier to add more complex logic as needed depending on testing goals. Because all test logic is incorporated into distributable test kits, anyone can download and run Inferno tests regardless of the inclusion of custom logic or behavior. No extensions need to be implemented on any platform that would like to run Inferno tests.

Whether TestScript or Inferno’s DSL is best in a given case largely depends on the Implementation Guide, the goals of testing, and the preference of the test writers. The Inferno DSL currently does not provide broad support for client testing, so those tests are best represented in TestScript or some other approach. For API testing, Inferno is optimized for testers that would like to create realistic test clients with a high level of automation and that are capable of performing complex behavior as defined in an Implementation Guide, and who have some level of comfort or interest in writing simple programs. TestScript is more optimized for situations where complex client behavior does not need to be described in order to accomplish testing goals, but does provide the opportunity to be extended as needed, understanding that using extensions may negatively impact the value of using TestScript.

Does Inferno test beyond US Core?

Yes, Inferno is able to test other Implementation Guides (IGs), though tests must be written specific to these IGs.

Inferno was initially created to provide conformance testing for ONC’s Standardized API certification criterion. This included requiring conformance to several FHIR IGs, include US Core. Since US Core was the first IG, Inferno is best known for testing this IG, and Inferno is particularly well suited to support IGs that also require conformance to US Core, but the goal of Inferno is to enable the creation of conformance tests for a wide variety of FHIR IGs.

How can I find Test Kits built with Inferno?

Visit our Community page to find Test Kits built with Inferno.

Can I host my own Inferno server?

Inferno is specifically designed such that Inferno Test Kits can be run in any environment that supports Docker, including on a desktop machine or shared server. For instructions on how to run a test kit locally or host them on a shared server, visit the Documentation.