Add API to revert vulnerability to reverted state

This change adds new API (vulnerabilities/:id/revert) to revert
vulnerability back to reverted state.

doc/api/vulnerabilities.md

@@ -220,3 +220,53 @@ Example response:
   "closed_at": null
 }
 ```
+
+## Revert vulnerability to detected state
+
+Reverts a given vulnerability to detected state. Returns status code `304` if the vulnerability is already in detected state.
+
+If an authenticated user does not have permission to
+[revert vulnerability to detected state](../user/permissions.md#project-members-permissions),
+this request will result in a `403` status code.
+
+```plaintext
+POST /vulnerabilities/:id/revert
+```
+
+| Attribute | Type | Required | Description |
+| --------- | ---- | -------- | ----------- |
+| `id` | integer or string | yes | The ID of a vulnerability to revert to detected state |
+
+```shell
+curl --request POST --header "PRIVATE-TOKEN: <your_access_token>" "https://gitlab.example.com/api/v4/vulnerabilities/5/dismiss"
+```
+
+Example response:
+
+```json
+{
+  "id": 2,
+  "title": "Predictable pseudorandom number generator",
+  "description": null,
+  "state": "detected",
+  "severity": "medium",
+  "confidence": "medium",
+  "report_type": "sast",
+  "project": {
+    "id": 32,
+    "name": "security-reports",
+    "full_path": "/gitlab-examples/security/security-reports",
+    "full_name": "gitlab-examples / security / security-reports"
+  },
+  "author_id": 1,
+  "updated_by_id": null,
+  "last_edited_by_id": null,
+  "closed_by_id": null,
+  "start_date": null,
+  "due_date": null,
+  "created_at": "2019-10-13T15:08:40.219Z",
+  "updated_at": "2019-10-13T15:09:40.382Z",
+  "last_edited_at": null,
+  "closed_at": null
+}
+```

doc/user/permissions.md

@@ -116,6 +116,7 @@ The following table depicts the various user permission levels in a project.
 | Create vulnerability from vulnerability finding **(ULTIMATE)** |   |     | ✓           | ✓        | ✓      |
 | Resolve vulnerability **(ULTIMATE)**              |         |            | ✓           | ✓        | ✓      |
 | Dismiss vulnerability **(ULTIMATE)**              |         |            | ✓           | ✓        | ✓      |
+| Revert vulnerability to detected state **(ULTIMATE)** |     |            | ✓           | ✓        | ✓      |
 | Apply code change suggestions                     |         |            | ✓           | ✓        | ✓      |
 | Create and edit wiki pages                        |         |            | ✓           | ✓        | ✓      |
 | Rewrite/remove Git tags                           |         |            | ✓           | ✓        | ✓      |

ee/changelogs/unreleased/230558-add-api-to-reverting-vulnerabilities-to-detected.yml

+---
+title: Add API to revert vulnerability to reverted state
+merge_request: 41784
+author:
+type: added

ee/lib/api/vulnerabilities.rb

@@ -69,6 +69,16 @@ module API
         @vulnerability = ::Vulnerabilities::ConfirmService.new(current_user, @vulnerability).execute
         render_vulnerability(@vulnerability)
       end
+
+      desc 'Revert a vulnerability to a detected state' do
+        success EE::API::Entities::Vulnerability
+      end
+      post ':id/revert' do
+        not_modified! if @vulnerability.detected?
+
+        @vulnerability = ::Vulnerabilities::RevertToDetectedService.new(current_user, @vulnerability).execute
+        render_vulnerability(@vulnerability)
+      end
     end
 
     params do

ee/spec/requests/api/vulnerabilities_spec.rb

@@ -375,4 +375,92 @@ RSpec.describe API::Vulnerabilities do
       it { expect { confirm_vulnerability }.to be_denied_for(:anonymous) }
     end
   end
+
+  describe 'POST /vulnerabilities:id/revert' do
+    before do
+      create_list(:vulnerabilities_occurrence, 2, vulnerability: vulnerability, project: vulnerability.project)
+    end
+
+    let_it_be(:project) { create(:project) }
+    let_it_be(:vulnerability) { create(:vulnerability, :dismissed, project: project) }
+
+    let(:vulnerability_id) { vulnerability.id }
+
+    subject(:revert_vulnerability_to_detected) { post api("/vulnerabilities/#{vulnerability_id}/revert", user) }
+
+    context 'with an authorized user with proper permissions' do
+      before do
+        project.add_developer(user)
+      end
+
+      it 'reverts a vulnerability and its associated findings to detected state' do
+        Timecop.freeze do
+          revert_vulnerability_to_detected
+
+          expect(response).to have_gitlab_http_status(:created)
+          expect(response).to match_response_schema('public_api/v4/vulnerability', dir: 'ee')
+
+          expect(vulnerability.reload).to(
+            have_attributes(state: 'detected', dismissed_by: nil, dismissed_at: nil))
+          expect(vulnerability.findings).to all not_have_vulnerability_dismissal_feedback
+        end
+      end
+
+      it_behaves_like 'responds with "not found" for an unknown vulnerability ID'
+
+      context 'when there is a revert error' do
+        before do
+          Grape::Endpoint.before_each do |endpoint|
+            allow(endpoint).to receive(:find_vulnerability!).and_wrap_original do |method, *args|
+              vulnerability = method.call(*args)
+
+              errors = ActiveModel::Errors.new(vulnerability)
+              errors.add(:base, 'something went wrong')
+
+              allow(vulnerability).to receive(:valid?).and_return(false)
+              allow(vulnerability).to receive(:errors).and_return(errors)
+
+              vulnerability
+            end
+          end
+        end
+
+        after do
+          # resetting according to the https://github.com/ruby-grape/grape#stubbing-helpers
+          Grape::Endpoint.before_each nil
+        end
+
+        it 'responds with error' do
+          revert_vulnerability_to_detected
+
+          expect(response).to have_gitlab_http_status(:bad_request)
+          expect(json_response['message']).to eq('base' => ['something went wrong'])
+        end
+      end
+
+      context 'if a vulnerability is already in detected state' do
+        let(:vulnerability) { create(:vulnerability, :detected, project: project) }
+
+        it 'responds with 304 Not Modified' do
+          revert_vulnerability_to_detected
+
+          expect(response).to have_gitlab_http_status(:not_modified)
+        end
+      end
+
+      it_behaves_like 'forbids access to vulnerability API endpoint in case of disabled features'
+    end
+
+    describe 'permissions' do
+      it { expect { revert_vulnerability_to_detected }.to be_allowed_for(:admin) }
+      it { expect { revert_vulnerability_to_detected }.to be_allowed_for(:owner).of(project) }
+      it { expect { revert_vulnerability_to_detected }.to be_allowed_for(:maintainer).of(project) }
+      it { expect { revert_vulnerability_to_detected }.to be_allowed_for(:developer).of(project) }
+
+      it { expect { revert_vulnerability_to_detected }.to be_denied_for(:auditor) }
+      it { expect { revert_vulnerability_to_detected }.to be_denied_for(:reporter).of(project) }
+      it { expect { revert_vulnerability_to_detected }.to be_denied_for(:guest).of(project) }
+      it { expect { revert_vulnerability_to_detected }.to be_denied_for(:anonymous) }
+    end
+  end
 end