fix: federated _service query SDL should not contain directives (ExpediaGroup#302)

Author: dariuszkuc

graphql-kotlin-federation/src/main/kotlin/com/expedia/graphql/federation/FederatedSchemaGeneratorHooks.kt

@@ -23,7 +23,8 @@ import kotlin.reflect.full.findAnnotation
  * Hooks for generating federated GraphQL schema.
  */
 open class FederatedSchemaGeneratorHooks(private val federatedTypeRegistry: FederatedTypeRegistry) : SchemaGeneratorHooks {
-
+    private val directiveRegex = "(^#.+$[\\r\\n])?^directive @\\w+.+$[\\r\\n]*".toRegex(setOf(RegexOption.MULTILINE, RegexOption.IGNORE_CASE))
+    private val scalarRegex = "(^#.+$[\\r\\n])?^scalar (_FieldSet|_Any)$[\\r\\n]*".toRegex(setOf(RegexOption.MULTILINE, RegexOption.IGNORE_CASE))
     private val validator = FederatedSchemaValidator()
 
     override fun willGenerateGraphQLType(type: KType): GraphQLType? = when (type.classifier) {
@@ -57,7 +58,11 @@ open class FederatedSchemaGeneratorHooks(private val federatedTypeRegistry: Fede
             val entityField = generateEntityFieldDefinition(entityTypeNames)
             federatedQuery.field(entityField)
 
+            // SDL returned by _service query should not contain directives or new scalars
             val sdl = originalSchema.print()
+                .replace(directiveRegex, "")
+                .replace(scalarRegex, "")
+                .trim()
             federatedCodeRegistry.dataFetcher(FieldCoordinates.coordinates(originalQuery.name, SERVICE_FIELD_DEFINITION.name), DataFetcher { _Service(sdl) })
             federatedCodeRegistry.dataFetcher(FieldCoordinates.coordinates(originalQuery.name, entityField.name), DataFetcher {
                 val representations: List<Map<String, Any>> = it.getArgument("representations")

graphql-kotlin-federation/src/test/kotlin/com/expedia/graphql/federation/execution/ServiceQueryResolverTest.kt

@@ -15,21 +15,6 @@ const val FEDERATED_SERVICE_SDL = """schema {
   query: Query
 }
 
-#Marks target field as external meaning it will be resolved by federated schema
-directive @external on FIELD_DEFINITION
-
-#Marks target object as part of the federated schema
-directive @extends on OBJECT | INTERFACE
-
-#Specifies the base type field set that will be selectable by the gateway
-directive @provides(fields: _FieldSet!) on FIELD_DEFINITION
-
-#Space separated list of primary keys needed to access federated object
-directive @key(fields: _FieldSet!) on OBJECT | INTERFACE
-
-#Specifies required input field set from the base type for a resolver
-directive @requires(fields: _FieldSet!) on FIELD_DEFINITION
-
 interface Product @extends @key(fields : "id") {
   id: String! @external
   reviews: [Review!]!
@@ -54,19 +39,7 @@ type Review {
 type User @extends @key(fields : "userId") {
   name: String! @external
   userId: Int! @external
-}
-
-#Federation type representing set of fields
-scalar _FieldSet
-
-#Directs the executor to include this field or fragment only when the `if` argument is true
-directive @include(if: Boolean!) on FIELD | FRAGMENT_SPREAD | INLINE_FRAGMENT
-
-#Directs the executor to skip this field or fragment when the `if`'argument is true.
-directive @skip(if: Boolean!) on FIELD | FRAGMENT_SPREAD | INLINE_FRAGMENT
-
-#Marks the target field/enum value as deprecated
-directive @deprecated(reason: String = "No longer supported") on FIELD_DEFINITION | ENUM_VALUE"""
+}"""
 
 class ServiceQueryResolverTest {