Graphql Helper improvements

These changes to GraphqlHelpers are generally useful, and backwards
compatible with existing code.

They include:

- The addition of `wrap_fields`
- `query_field` accepts an optional type argument
- We assert that none of our queries result in internal server errors
- We use fresh responses by default (helpful for assertions involving
  multiple requests).
- We assert that all types are known in the schema.

spec/requests/api/graphql/project/release_spec.rb

@@ -435,13 +435,13 @@ RSpec.describe 'Query.project(fullPath).release(tagName)' do
     let_it_be_with_reload(:release) { create(:release, project: project) }
 
     let(:release_fields) do
-      query_graphql_field(%{
+      %{
         milestones {
           nodes {
             title
           }
         }
-      })
+      }
     end
 
     let(:actual_milestone_title_order) do

spec/support/helpers/graphql_helpers.rb

@@ -125,11 +125,15 @@ module GraphqlHelpers
   end
 
   def graphql_query_for(name, attributes = {}, fields = nil)
-    <<~QUERY
-    {
-      #{query_graphql_field(name, attributes, fields)}
-    }
-    QUERY
+    type = GitlabSchema.types['Query'].fields[GraphqlHelpers.fieldnamerize(name)]&.type
+    wrap_query(query_graphql_field(name, attributes, fields, type))
+  end
+
+  def wrap_query(query)
+    q = query.to_s
+    return q if q.starts_with?('{')
+
+    "{ #{q} }"
   end
 
   def graphql_mutation(name, input, fields = nil, &block)
@@ -219,12 +223,13 @@ module GraphqlHelpers
     "#{namerized}#{field_params}"
   end
 
-  def query_graphql_field(name, attributes = {}, fields = nil)
+  def query_graphql_field(name, attributes = {}, fields = nil, type = nil)
+    type ||= name.to_s.classify
     attributes, fields = [nil, attributes] if fields.nil? && !attributes.is_a?(Hash)
 
     field = field_with_params(name, attributes)
 
-    field + wrap_fields(fields || all_graphql_fields_for(name.to_s.classify)).to_s
+    field + wrap_fields(fields || all_graphql_fields_for(type)).to_s
   end
 
   def page_info_selection
@@ -281,8 +286,8 @@ module GraphqlHelpers
     allow_high_graphql_recursion
     allow_high_graphql_transaction_threshold
 
-    type = GitlabSchema.types[class_name.to_s]
-    return "" unless type
+    type = class_name.respond_to?(:kind) ? class_name : GitlabSchema.types[class_name.to_s]
+    raise "#{class_name} is not a known type in the GitlabSchema" unless type
 
     # We can't guess arguments, so skip fields that require them
     skip = ->(name, field) { excluded.include?(name) || required_arguments?(field) }
@@ -291,7 +296,7 @@ module GraphqlHelpers
   end
 
   def with_signature(variables, query)
-    %Q[query(#{variables.map(&:sig).join(', ')}) #{query}]
+    %Q[query(#{variables.map(&:sig).join(', ')}) #{wrap_query(query)}]
   end
 
   def var(type)
@@ -309,6 +314,10 @@ module GraphqlHelpers
   def post_graphql(query, current_user: nil, variables: nil, headers: {})
     params = { query: query, variables: serialize_variables(variables) }
     post api('/', current_user, version: 'graphql'), params: params, headers: headers
+
+    if graphql_errors # Errors are acceptable, but not this one:
+      expect(graphql_errors).not_to include(a_hash_including('message' => 'Internal server error'))
+    end
   end
 
   def post_graphql_mutation(mutation, current_user: nil)
@@ -378,10 +387,8 @@ module GraphqlHelpers
   end
 
   # Raises an error if no data is found
-  def graphql_data(body = json_response)
-    # Note that `json_response` is defined as `let(:json_response)` and
-    # therefore, in a spec with multiple queries, will only contain data
-    # from the _first_ query, not subsequent ones
+  # NB: We use fresh_response_data to support tests that make multiple requests.
+  def graphql_data(body = fresh_response_data)
     body['data'] || (raise NoData, graphql_errors(body))
   end