Add `discussions` and `notes` fields for `VulnerabilityType`

Implement `Notes::Noteable` interface in `VulnerabilityType` to add
`discussions` and `notes` fields.

To do so, we had to remove `definiton_methods` DSL method call which is
defined in the private API.

app/graphql/types/notes/noteable_type.rb

@@ -8,24 +8,24 @@ module Types
       field :notes, Types::Notes::NoteType.connection_type, null: false, description: "All notes on this noteable"
       field :discussions, Types::Notes::DiscussionType.connection_type, null: false, description: "All discussions on this noteable"
 
-      definition_methods do
-        def resolve_type(object, context)
-          case object
-          when Issue
-            Types::IssueType
-          when MergeRequest
-            Types::MergeRequestType
-          when Snippet
-            Types::SnippetType
-          when ::DesignManagement::Design
-            Types::DesignManagement::DesignType
-          when ::AlertManagement::Alert
-            Types::AlertManagement::AlertType
-          else
-            raise "Unknown GraphQL type for #{object}"
-          end
+      def self.resolve_type(object, context)
+        case object
+        when Issue
+          Types::IssueType
+        when MergeRequest
+          Types::MergeRequestType
+        when Snippet
+          Types::SnippetType
+        when ::DesignManagement::Design
+          Types::DesignManagement::DesignType
+        when ::AlertManagement::Alert
+          Types::AlertManagement::AlertType
+        else
+          raise "Unknown GraphQL type for #{object}"
         end
       end
     end
   end
 end
+
+Types::Notes::NoteableType.prepend_if_ee('::EE::Types::Notes::NoteableType')

doc/api/graphql/reference/gitlab_schema.graphql

@@ -18688,7 +18688,7 @@ type VulnerabilitiesCountByDayEdge {
 """
 Represents a vulnerability
 """
-type Vulnerability {
+type Vulnerability implements Noteable {
   """
   Description of the vulnerability
   """
@@ -18699,6 +18699,31 @@ type Vulnerability {
   """
   detectedAt: Time!
 
+  """
+  All discussions on this noteable
+  """
+  discussions(
+    """
+    Returns the elements in the list that come after the specified cursor.
+    """
+    after: String
+
+    """
+    Returns the elements in the list that come before the specified cursor.
+    """
+    before: String
+
+    """
+    Returns the first _n_ elements from the list.
+    """
+    first: Int
+
+    """
+    Returns the last _n_ elements from the list.
+    """
+    last: Int
+  ): DiscussionConnection!
+
   """
   GraphQL ID of the vulnerability
   """
@@ -18744,6 +18769,31 @@ type Vulnerability {
   """
   location: VulnerabilityLocation
 
+  """
+  All notes on this noteable
+  """
+  notes(
+    """
+    Returns the elements in the list that come after the specified cursor.
+    """
+    after: String
+
+    """
+    Returns the elements in the list that come before the specified cursor.
+    """
+    before: String
+
+    """
+    Returns the first _n_ elements from the list.
+    """
+    first: Int
+
+    """
+    Returns the last _n_ elements from the list.
+    """
+    last: Int
+  ): NoteConnection!
+
   """
   Primary identifier of the vulnerability.
   """

doc/api/graphql/reference/gitlab_schema.json

@@ -33867,6 +33867,11 @@
               "kind": "OBJECT",
               "name": "Snippet",
               "ofType": null
+            },
+            {
+              "kind": "OBJECT",
+              "name": "Vulnerability",
+              "ofType": null
             }
           ]
         },
@@ -54731,6 +54736,63 @@
               "isDeprecated": false,
               "deprecationReason": null
             },
+            {
+              "name": "discussions",
+              "description": "All discussions on this noteable",
+              "args": [
+                {
+                  "name": "after",
+                  "description": "Returns the elements in the list that come after the specified cursor.",
+                  "type": {
+                    "kind": "SCALAR",
+                    "name": "String",
+                    "ofType": null
+                  },
+                  "defaultValue": null
+                },
+                {
+                  "name": "before",
+                  "description": "Returns the elements in the list that come before the specified cursor.",
+                  "type": {
+                    "kind": "SCALAR",
+                    "name": "String",
+                    "ofType": null
+                  },
+                  "defaultValue": null
+                },
+                {
+                  "name": "first",
+                  "description": "Returns the first _n_ elements from the list.",
+                  "type": {
+                    "kind": "SCALAR",
+                    "name": "Int",
+                    "ofType": null
+                  },
+                  "defaultValue": null
+                },
+                {
+                  "name": "last",
+                  "description": "Returns the last _n_ elements from the list.",
+                  "type": {
+                    "kind": "SCALAR",
+                    "name": "Int",
+                    "ofType": null
+                  },
+                  "defaultValue": null
+                }
+              ],
+              "type": {
+                "kind": "NON_NULL",
+                "name": null,
+                "ofType": {
+                  "kind": "OBJECT",
+                  "name": "DiscussionConnection",
+                  "ofType": null
+                }
+              },
+              "isDeprecated": false,
+              "deprecationReason": null
+            },
             {
               "name": "id",
               "description": "GraphQL ID of the vulnerability",
@@ -54856,6 +54918,63 @@
               "isDeprecated": false,
               "deprecationReason": null
             },
+            {
+              "name": "notes",
+              "description": "All notes on this noteable",
+              "args": [
+                {
+                  "name": "after",
+                  "description": "Returns the elements in the list that come after the specified cursor.",
+                  "type": {
+                    "kind": "SCALAR",
+                    "name": "String",
+                    "ofType": null
+                  },
+                  "defaultValue": null
+                },
+                {
+                  "name": "before",
+                  "description": "Returns the elements in the list that come before the specified cursor.",
+                  "type": {
+                    "kind": "SCALAR",
+                    "name": "String",
+                    "ofType": null
+                  },
+                  "defaultValue": null
+                },
+                {
+                  "name": "first",
+                  "description": "Returns the first _n_ elements from the list.",
+                  "type": {
+                    "kind": "SCALAR",
+                    "name": "Int",
+                    "ofType": null
+                  },
+                  "defaultValue": null
+                },
+                {
+                  "name": "last",
+                  "description": "Returns the last _n_ elements from the list.",
+                  "type": {
+                    "kind": "SCALAR",
+                    "name": "Int",
+                    "ofType": null
+                  },
+                  "defaultValue": null
+                }
+              ],
+              "type": {
+                "kind": "NON_NULL",
+                "name": null,
+                "ofType": {
+                  "kind": "OBJECT",
+                  "name": "NoteConnection",
+                  "ofType": null
+                }
+              },
+              "isDeprecated": false,
+              "deprecationReason": null
+            },
             {
               "name": "primaryIdentifier",
               "description": "Primary identifier of the vulnerability.",
@@ -55025,7 +55144,11 @@
           ],
           "inputFields": null,
           "interfaces": [
-
+            {
+              "kind": "INTERFACE",
+              "name": "Noteable",
+              "ofType": null
+            }
           ],
           "enumValues": null,
           "possibleTypes": null

ee/app/graphql/ee/types/notes/noteable_type.rb

+# frozen_string_literal: true
+
+module EE
+  module Types
+    module Notes
+      module NoteableType
+        module ClassMethods
+          def resolve_type(object, *)
+            return ::Types::VulnerabilityType if ::Vulnerability === object
+
+            super
+          end
+        end
+
+        def self.prepended(base)
+          base.singleton_class.prepend(ClassMethods)
+        end
+      end
+    end
+  end
+end

ee/app/graphql/types/vulnerability_type.rb

@@ -5,6 +5,8 @@ module Types
     graphql_name 'Vulnerability'
     description 'Represents a vulnerability'
 
+    implements(Types::Notes::NoteableType)
+
     authorize :read_vulnerability
 
     expose_permissions Types::PermissionTypes::Vulnerability

ee/changelogs/unreleased/223814_add_notes_and_discussions_to_vulnerability_type.yml

+---
+title: Add `discussions` and `notes` fields for VulnerabilityType on GraphQL API
+merge_request: 42892
+author:
+type: added

ee/spec/graphql/ee/types/notes/noteable_type_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe EE::Types::Notes::NoteableType do
+  let(:extended_class) { Types::Notes::NoteableType }
+
+  describe ".resolve_type" do
+    it 'knows the correct type for objects' do
+      expect(extended_class.resolve_type(build(:issue), {})).to eq(Types::IssueType)
+      expect(extended_class.resolve_type(build(:merge_request), {})).to eq(Types::MergeRequestType)
+      expect(extended_class.resolve_type(build(:design), {})).to eq(Types::DesignManagement::DesignType)
+      expect(extended_class.resolve_type(build(:alert_management_alert), {})).to eq(Types::AlertManagement::AlertType)
+      expect(extended_class.resolve_type(build(:vulnerability), {})).to eq(Types::VulnerabilityType)
+    end
+  end
+end

ee/spec/graphql/types/vulnerability_type_spec.rb

@@ -23,7 +23,9 @@ RSpec.describe GitlabSchema.types['Vulnerability'] do
        identifiers
        project
        issueLinks
-       detected_at]
+       detected_at
+       notes
+       discussions]
   end
 
   before do