[SHORT VERSION] How to fast generate your API Test with OpenAPI Tools and Rest-Assured

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How to fast generate your API Test with OpenAPI Tools and Rest-Assured Elias Nogueira Short version

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ELIAS NOGUEIRA Senior Principal Software Engineer Brazil Java Champion Oracle ACE for Java Java Magazine NL Editor

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preconditions

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For this talk, you must know about: ● Java (intermediate) ● Maven (intermediate) ● REST-Assured (advanced) ● OpenAPI Specs (understand the spec) ● Architecture (intermediate) preconditions eliasnogueira.com

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generating the code

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generating the code eliasnogueira.com wagon-maven-plugin openapi-spec openapi generator maven-plugin java code download is used by generate

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download the spec file The wagon-maven-plugin will help us to download a file to a specific directory. In general, we will tell the plugin to: ○ download a file ○ describe the file location ○ describe the destination eliasnogueira.com

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download the spec file eliasnogueira.com org.codehaus.mojo wagon-maven-plugin ${wagon-maven-plugin.version} download-credit-api-spec download-single generate-sources URL-TO-THE-FILE-INCLUDING-FILE-NAME-AND-EXTENSION ${project.basedir}/target/openapiSpecs

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generate the Client API The openapi-generator-maven-plugin will help us to generate the Client API and it models based on the Open API file specification. In general, we will tell the plugin to: ○ look at a specific folder to know the spec file ○ define the main, api and model packages ○ use REST Assured as a support library ○ set the serialization library eliasnogueira.com

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generate the Client API eliasnogueira.com generate-client-api-code generate generate-sources ${project.build.directory}/openapiSpecs/credit-api.yaml com.eliasnogueira.credit.invoker com.eliasnogueira.credit.api com.eliasnogueira.credit.model java false false rest-assured jackson

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generate-client-api-code generate generate-sources ${project.build.directory}/openapiSpecs/credit-api.yaml com.eliasnogueira.credit.invoker com.eliasnogueira.credit.api com.eliasnogueira.credit.model java false false rest-assured jackson generate the Client API eliasnogueira.com unique id in case of many generator

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code generated

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code generated The code is generated at the target/generated-sources/openapi folder. There will be three main packages: ● api: client api code ● invoker: class specifics for the target library (REST-Assured) ● model: all models from the spec eliasnogueira.com

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code generated The most important code generated are the Api ones. They have all the API operations from the OpenAPI spec ready to be used with REST-Assured as it has the request and response specifications. eliasnogueira.com public static class GetRestrictionV1Oper implements Oper { public static final Method REQ_METHOD = GET; public static final String REQ_URI = "/api/v1/restrictions/{cpf}"; private RequestSpecBuilder reqSpec; private ResponseSpecBuilder respSpec; public GetRestrictionV1Oper(RequestSpecBuilder reqSpec) { this.reqSpec = reqSpec; reqSpec.setAccept("application/json"); this.respSpec = new ResponseSpecBuilder(); } }

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architecture

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architecture Proposed architecture eliasnogueira.com *Test RestApiClientBuilder *ApiClient Client API abstraction *ApiService Service abstraction build use use

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architecture *ApiClient This will abstract the current Client API class generated by the OpenAPI Generator, based on REST Assured, and will use the RestClientApiBuilder to add the common request specification. The generated Client Api class adds an inner class per HTTP request matching the OpenAPI spec. eliasnogueira.com

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architecture eliasnogueira.com public class RestrictionsApi { public static RestrictionsApi restrictions(Supplier reqSpecSupplier) { return new RestrictionsApi(reqSpecSupplier); } public OneUsingGETOper oneUsingGET() { return new OneUsingGETOper(createReqSpec()); } }

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architecture eliasnogueira.com public static class OneUsingGETOper implements Oper { public static final Method REQ_METHOD = GET; public static final String REQ_URI = "/api/v1/restrictions/{cpf}"; @Override public T execute(Function handler) { // magic } public static final String CPF_PATH = "cpf"; public OneUsingGETOper cpfPath(Object cpf) { reqSpec.addPathParam(CPF_PATH, cpf); return this; } }

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architecture *ApiClient Creation We need to use the RestApiClientBuilder to build the Client Api instance to add the URL and port. Then we add a method per HTTP request. This is a recommended approach to ease any change (even to a different library). eliasnogueira.com

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architecture RestApiClientBuilder The main necessity of this class is to add, to all requests, the baseUri, and the port. The basePath is not necessary as the generated client already has it. eliasnogueira.com public class RestApiClientBuilder { public T build(Function, T> clientCreator) { Supplier requestSpecBuilderSupplier = () -> new RequestSpecBuilder() .addRequestSpecification( new RequestSpecBuilder() .setBaseUri("http://localhost") .setPort(8088) .build()); return clientCreator.apply(requestSpecBuilderSupplier); } }

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architecture eliasnogueira.com public class RestrictionsApiClient { private RestrictionsApi restrictionsApi = new RestApiClientBuilder().build(RestrictionsApi::restrictions); public Response queryCpf(String cpf) { return restrictionsApi.oneUsingGET().cpfPath(cpf).execute(Function.identity()); } } build of the Client Api using the RestApiClientBuilder

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architecture eliasnogueira.com public class RestrictionsApiClient { private RestrictionsApi restrictionsApi = new RestApiClientBuilder().build(RestrictionsApi::restrictions); public Response queryCpf(String cpf) { return restrictionsApi.oneUsingGET().cpfPath(cpf).execute(Function.identity()); } } abstracting the internal (ugly) Client Api usage - returning a generic response - adding a meaningful name - adding the path parameter as the method parameter

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architecture eliasnogueira.com public class RestrictionsApiClient { private RestrictionsApi restrictionsApi = new RestApiClientBuilder().build(RestrictionsApi::restrictions); public Response queryCpf(String cpf) { return restrictionsApi.oneUsingGET().cpfPath(cpf).execute(Function.identity()); } } using the auto-generated internal Client Api method

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architecture *ApiService The *ApiService abstraction will use the *ApiClient abstraction to consume its methods in different ways. This is the class we will use in the tests. The service can have one or multiple actions from the *ApiClient and it can be related to the Mediator design pattern, as it encapsulates how a set of objects (methods) interact. eliasnogueira.com

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architecture *ApiService - Example We do have two test for the Restrictions API: ○ Expecting a restriction ○ Not expecting a restriction We will create the request for both, returning the correct response, in the service abstraction. eliasnogueira.com

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architecture eliasnogueira.com public class RestrictionsApiService { private RestrictionsApiClient restrictionsApiClient = new RestrictionsApiClient(); /** * Query CPF without a restriction */ public boolean queryCpf(String cpf) { restrictionsApiClient.queryCpf(cpf).then().statusCode(HttpStatus.SC_NOT_FOUND); return true; } public MessageV1 queryCpfWithRestriction(String cpf) { return restrictionsApiClient.queryCpf(cpf).then(). statusCode(HttpStatus.SC_OK).extract().as(MessageV1.class); } }

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architecture Test Now the tests will be created using only the Service class. The different is that we don’t need to use the raw REST Assured methods anymore, relying only in the Service. The structure of precondition, action and assert will be always present in the new way to create tests. eliasnogueira.com

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architecture eliasnogueira.com @Test void shouldReturnRestriction() { given() .spec(SharedRequestSpecs.cpfPathParameter("62648716050")) .when() .get("/restrictions/{cpf}") .then() .statusCode(HttpStatus.SC_OK) .body("message", CoreMatchers.is("CPF 62648716050 has a restriction")); } @Test void shouldReturnRestriction() { RestrictionsApiService restrictionsApiService = new RestrictionsApiService(); MessageV1 message = restrictionsApiService.queryCpfWithRestriction("60094146012"); Assertions.assertThat(message.getMessage()).contains("60094146012"); } Raw REST Assured Test REST Assured Test using Client – Service abstraction

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architecture Test The usage of the service abstraction add more readability and help us to decrease the maintainability as we will have only one place to change it behaviour (client or service). eliasnogueira.com @Test void shouldReturnRestriction() { RestrictionsApiService restrictionsApiService = new RestrictionsApiService(); MessageV1 message = restrictionsApiService.queryCpfWithRestriction("60094146012"); Assertions.assertThat(message.getMessage()).contains("60094146012"); }

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architecture eliasnogueira.com @Test void shouldReturnRestriction() { RestrictionsApiService restrictionsApiService = new RestrictionsApiService(); MessageV1 message = restrictionsApiService.queryCpfWithRestriction("60094146012"); Assertions.assertThat(message.getMessage()).contains("60094146012"); }

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architecture BaseApiConfiguration Within the new approach, the general configuration is now being applied using the RestClientApiBuilder class, as it created a common request specification for all the requests. We can either move the previous configurations from the BaseApiConfiguration class to the RestClientApiBuilder or continue to use the BaseApiConfiguration without the baseUri, basePath, and port. eliasnogueira.com

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architecture Recommendation A better approach is to use the RestClientApiBuilder to deal only with the global request actions and the BaseApiConfiguration with the configurations related to the test. Both classes do different things, and they must have a single responsibility. eliasnogueira.com

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THANK YOU! @eliasnogueira