Introduce generic video constant manager for plugins

Allow a plugin developer to get back constants values,
and reset constants deletions or additions.

server/tests/plugins/video-constants.ts

@@ -9,8 +9,11 @@ import {
   getVideo,
   getVideoCategories,
   getVideoLanguages,
-  getVideoLicences, getVideoPlaylistPrivacies, getVideoPrivacies,
+  getVideoLicences,
+  getVideoPlaylistPrivacies,
+  getVideoPrivacies,
   installPlugin,
+  makeGetRequest,
   setAccessTokensToServers,
   uninstallPlugin,
   uploadVideo
@@ -173,6 +176,38 @@ describe('Test plugin altering video constants', function () {
     }
   })
 
+  it('Should be able to reset categories', async function () {
+    await installPlugin({
+      url: server.url,
+      accessToken: server.accessToken,
+      path: getPluginTestPath('-video-constants')
+    })
+
+    let { body: categories } = await getVideoCategories(server.url)
+
+    expect(categories[1]).to.not.exist
+    expect(categories[2]).to.not.exist
+
+    expect(categories[42]).to.exist
+    expect(categories[43]).to.exist
+
+    await makeGetRequest({
+      url: server.url,
+      token: server.accessToken,
+      path: '/plugins/test-video-constants/router/reset-categories',
+      statusCodeExpected: HttpStatusCode.NO_CONTENT_204
+    })
+
+    const { body } = await getVideoCategories(server.url)
+    categories = body
+
+    expect(categories[1]).to.exist
+    expect(categories[2]).to.exist
+
+    expect(categories[42]).to.not.exist
+    expect(categories[43]).to.not.exist
+  })
+
   after(async function () {
     await cleanupTests([ server ])
   })