Chore: Add counterpart for constants for tests

Author: barboraplasovska

DatadogRUM/Tests/Instrumentation/Resources/URLSessionRUMResourcesHandlerTests.swift

@@ -954,10 +954,10 @@ class URLSessionRUMResourcesHandlerTests: XCTestCase {
 
         // Given
         var mockRequest: URLRequest = .mockWith(url: "https://graphql.example.com/api")
-        mockRequest.setValue("GetUser", forHTTPHeaderField: GraphQLHeaders.operationName)
-        mockRequest.setValue("query", forHTTPHeaderField: GraphQLHeaders.operationType)
-        mockRequest.setValue("{\"userId\":\"123\"}", forHTTPHeaderField: GraphQLHeaders.variables)
-        mockRequest.setValue("query GetUser($userId: ID!) { user(id: $userId) { name } }", forHTTPHeaderField: GraphQLHeaders.payload)
+        mockRequest.setValue("GetUser", forHTTPHeaderField: ExpectedGraphQLHeaders.operationName)
+        mockRequest.setValue("query", forHTTPHeaderField: ExpectedGraphQLHeaders.operationType)
+        mockRequest.setValue("{\"userId\":\"123\"}", forHTTPHeaderField: ExpectedGraphQLHeaders.variables)
+        mockRequest.setValue("query GetUser($userId: ID!) { user(id: $userId) { name } }", forHTTPHeaderField: ExpectedGraphQLHeaders.payload)
 
         let immutableRequest = ImmutableRequest(request: mockRequest)
         let taskInterception = URLSessionTaskInterception(request: immutableRequest, isFirstParty: false)
@@ -989,8 +989,8 @@ class URLSessionRUMResourcesHandlerTests: XCTestCase {
 
         // Given
         var mockRequest: URLRequest = .mockWith(url: "https://graphql.example.com/api")
-        mockRequest.setValue("FailedMutation", forHTTPHeaderField: GraphQLHeaders.operationName)
-        mockRequest.setValue("mutation", forHTTPHeaderField: GraphQLHeaders.operationType)
+        mockRequest.setValue("FailedMutation", forHTTPHeaderField: ExpectedGraphQLHeaders.operationName)
+        mockRequest.setValue("mutation", forHTTPHeaderField: ExpectedGraphQLHeaders.operationType)
 
         let immutableRequest = ImmutableRequest(request: mockRequest)
         let taskInterception = URLSessionTaskInterception(request: immutableRequest, isFirstParty: false)
@@ -1028,3 +1028,12 @@ class URLSessionRUMResourcesHandlerTests: XCTestCase {
         return dict
     }
 }
+
+// MARK: - Test Helpers
+
+struct ExpectedGraphQLHeaders {
+    static let operationName: String = "_dd-custom-header-graph-ql-operation-name"
+    static let operationType: String = "_dd-custom-header-graph-ql-operation-type"
+    static let variables: String = "_dd-custom-header-graph-ql-variables"
+    static let payload: String = "_dd-custom-header-graph-ql-payload"
+}