Ensure we don't track apdex for failing queries

spec/lib/gitlab/graphql/tracers/metrics_tracer_spec.rb

 # frozen_string_literal: true
 
-require 'fast_spec_helper'
+require 'spec_helper'
 require 'rspec-parameterized'
 require "support/graphql/fake_query_type"
 
@@ -36,7 +36,7 @@ RSpec.describe Gitlab::Graphql::Tracers::MetricsTracer do
     end
 
     with_them do
-      it 'increments sli' do
+      it 'increments apdex sli' do
         # Trigger initialization
         fake_schema
 
@@ -56,5 +56,13 @@ RSpec.describe Gitlab::Graphql::Tracers::MetricsTracer do
         fake_schema.execute("query lorem { helloWorld }")
       end
     end
+
+    it "does not record apdex for failing queries" do
+      query_string = "query fooOperation { breakingField }"
+
+      expect(Gitlab::Metrics::RailsSlis.graphql_query_apdex).not_to receive(:increment)
+
+      expect { fake_schema.execute(query_string) }.to raise_error(/This field is supposed to break/)
+    end
   end
 end