Reduce duplicated code in tests

[amatosg]

Is your feature request related to a problem? Please describe.
Not really, just an improvement

Describe the solution you'd like
Instead of having each test call

given()
.auth()
.preemptive()
.oauth2(adminToken)
.accept(APPLICATION_JSON)
.when()
.get("/api/payment-terms")
.then()
.statusCode(OK.getStatusCode())
.contentType(APPLICATION_JSON)
.extract()
.as(LIST_OF_ENTITY_TYPE)
.size();

we could have a private method:

private int getSizeBeforeCreate() {
    return given()
            .auth()
            .preemptive()
            .oauth2(adminToken)
            .accept(APPLICATION_JSON)
            .when()
            .get("/api/entity")
            .then()
            .statusCode(OK.getStatusCode())
            .contentType(APPLICATION_JSON)
            .extract()
            .as(LIST_OF_ENTITY_TYPE)
            .size();
}

and in each test just call var databaseSizeBeforeCreate = getSizeBeforeCreate();

The same applies for persisting the entity;

private ValidatableResponse persistEntity() {
    return given()
            .auth()
            .preemptive()
            .oauth2(adminToken)
            .contentType(APPLICATION_JSON)
            .accept(APPLICATION_JSON)
            .body(entityDTO)
            .when()
            .post("/api/entity")
            .then();
}

then call it and test what you need (if it should fail, success, etc), like

// Create the entity
entityDTO = persistEntity()
    .statusCode(CREATED.getStatusCode())
    .extract()
    .as(ENTITY_TYPE);

// Bad request for whatever reason
entityDTO.id = 1L; // create with an existing ID
persistEntity().statusCode(BAD_REQUEST.getStatusCode());

Maybe even have the endpoint as parameter in case future extensions test custom implementation.

Describe alternatives you've considered
doing it manually