Add metric definition schema validation spec

config/metrics/objects_schemas/projects_with_enabled_alert_integrations_histogram.json

 {
   "type": "object",
-  "description": "Histogram (buckets 1 to 100) of projects with at least 1 enabled integration"
+  "description": "Histogram (buckets 1 to 100) of projects with at least 1 enabled integration",
   "propertyNames": {
     "pattern": "^[1-9][0-9]?0?$"
   }

ee/spec/config/metrics/every_metric_definition_spec.rb

@@ -51,7 +51,6 @@ RSpec.describe 'Every metric definition' do
     Gitlab::Usage::MetricDefinition
       .definitions
       .select { |k, v| v.respond_to?(:value_json_schema) }
-      .keys
   end
 
   # Recursively traverse nested Hash of a generated Usage Ping to return an Array of key paths
@@ -67,7 +66,7 @@ RSpec.describe 'Every metric definition' do
   end
 
   def object_with_schema?(key_path)
-    metric_files_with_schema.include?(key_path)
+    metric_files_with_schema.keys.include?(key_path)
   end
 
   before do
@@ -81,4 +80,14 @@ RSpec.describe 'Every metric definition' do
   it 'is included in the Usage Ping hash structure' do
     expect(metric_files_key_paths).to match_array(usage_ping_key_paths)
   end
+
+  context 'with value json schema' do
+    it 'has a valid structure' do
+      metric_files_with_schema.each do |key_path, metric|
+        structure = usage_ping.dig(*key_path.split('.').map(&:to_sym))
+
+        expect(structure).to match_metric_definition_schema(metric.value_json_schema)
+      end
+    end
+  end
 end

lib/gitlab/usage/metrics/instrumentations/collected_data_categories_metric.rb

@@ -6,7 +6,7 @@ module Gitlab
       module Instrumentations
         class CollectedDataCategoriesMetric < GenericMetric
           value do
-            ::ServicePing::PermitDataCategoriesService.new.execute
+            ::ServicePing::PermitDataCategoriesService.new.execute.to_a
           end
         end
       end

spec/support/matchers/schema_matcher.rb

@@ -45,6 +45,17 @@ RSpec::Matchers.define :match_response_schema do |schema, dir: nil, **options|
   end
 end
 
+RSpec::Matchers.define :match_metric_definition_schema do |path, dir: nil, **options|
+  match do |data|
+    schema_path = Pathname.new(Rails.root.join(dir.to_s, path).to_s)
+    validator = SchemaPath.validator(schema_path)
+
+    data = data.stringify_keys if data.is_a? Hash
+
+    validator.valid?(data)
+  end
+end
+
 RSpec::Matchers.define :match_snowplow_schema do |schema, dir: nil, **options|
   match do |data|
     schema_path = Pathname.new(Rails.root.join(dir.to_s, 'spec', "fixtures/product_intelligence/#{schema}.json").to_s)