The OpenApiLibCore library is a utility library that is meant to simplify creation of other Robot Framework libraries for API testing based on the information in an OpenAPI document (also known as Swagger document). This document explains how to use the OpenApiLibCore library.

My RoboCon 2022 talk about OpenApiDriver and OpenApiLibCore can be found here

For more information about Robot Framework, see http://robotframework.org.

Note: OpenApiLibCore is still being developed so there are currently restrictions / limitations that you may encounter when using this library to run tests against an API. See Limitations for details.

If you already have Python >= 3.8 with pip installed, you can simply run:

pip install --upgrade robotframework-openapi-libcore

The OpenAPI Specification (OAS) defines a standard, language-agnostic interface to RESTful APIs, see https://swagger.io/specification/

The OpenApiLibCore implements a number of Robot Framework keywords that make it easy to interact with an OpenAPI implementation by using the information in the openapi document (Swagger file), for examply by automatic generation of valid values for requests based on the schema information in the document.

Note: OpenApiLibCore is designed for APIs based on the OAS v3 The library has not been tested for APIs based on the OAS v2.

Before trying to use the keywords exposed by OpenApiLibCore on the target API it's recommended to first ensure that the openapi document for the API is valid under the OpenAPI Specification.

This can be done using the command line interface of a package that is installed as a prerequisite for OpenApiLibCore. Both a local openapi.json or openapi.yaml file or one hosted by the API server can be checked using the prance validate <reference_to_file> shell command:

prance validate --backend=openapi-spec-validator http://localhost:8000/openapi.json
Processing "http://localhost:8000/openapi.json"...
 -> Resolving external references.
Validates OK as OpenAPI 3.0.2!

prance validate --backend=openapi-spec-validator /tests/files/petstore_openapi.yaml
Processing "/tests/files/petstore_openapi.yaml"...
 -> Resolving external references.
Validates OK as OpenAPI 3.0.2!

You'll have to change the url or file reference to the location of the openapi document for your API.

Note: Although recursion is technically allowed under the OAS, tool support is limited and changing the OAS to not use recursion is recommended. OpenApiLibCore has limited support for parsing OpenAPI documents with recursion in them. See the recursion_limit and recursion_default parameters.

If the openapi document passes this validation, the next step is trying to do a test run with a minimal test suite. The example below can be used, with source, origin and 'endpoint' altered to fit your situation.

*** Settings ***
Library            OpenApiLibCore
...                    source=http://localhost:8000/openapi.json
...                    origin=http://localhost:8000

*** Test Cases ***
Getting Started
    ${url}=    Get Valid Url    endpoint=/employees/{employee_id}   method=get

Running the above suite for the first time may result in an error / failed test. You should look at the Robot Framework log.html to determine the reasons for the failing tests. Depending on the reasons for the failures, different solutions are possible.

Details about the OpenApiLibCore library parameters and keywords that you may need can be found here.

The OpenApiLibCore also support handling of relations between resources within the scope of the API being validated as well as handling dependencies on resources outside the scope of the API. In addition there is support for handling restrictions on the values of parameters and properties.

Details about the mappings_path variable usage can be found here.

There are currently a number of limitations to supported API structures, supported data types and properties. The following list details the most important ones:

• Only JSON request and response bodies are supported.
• No support for per-endpoint authorization levels.
• Parsing of OAS 3.1 documents is supported by the parsing tools, but runtime behavior is untested.