Keyword/phrase filtering (#7905)

* Add keyword filtering

    GET|POST       /api/v1/filters
    GET|PUT|DELETE /api/v1/filters/:id

- Irreversible filters can drop toots from home or notifications
- Other filters can hide toots through the client app
- Filters use a phrase valid in particular contexts, expiration

* Make sure expired filters don't get applied client-side

* Add missing API methods

* Remove "regex filter" from column settings

* Add tests

* Add test for FeedManager

* Add CustomFilter test

* Add UI for managing filters

* Add streaming API event to allow syncing filters

* Fix tests

spec/controllers/api/v1/filter_controller_spec.rb

@@ -0,0 +1,81 @@
+require 'rails_helper'
+
+RSpec.describe Api::V1::FiltersController, type: :controller do
+  render_views
+
+  let(:user)  { Fabricate(:user) }
+  let(:token) { Fabricate(:accessible_access_token, resource_owner_id: user.id, scopes: 'read write') }
+
+  before do
+    allow(controller).to receive(:doorkeeper_token) { token }
+  end
+
+  describe 'GET #index' do
+    let!(:filter) { Fabricate(:custom_filter, account: user.account) }
+
+    it 'returns http success' do
+      get :index
+      expect(response).to have_http_status(200)
+    end
+  end
+
+  describe 'POST #create' do
+    before do
+      post :create, params: { phrase: 'magic', context: %w(home), irreversible: true }
+    end
+
+    it 'returns http success' do
+      expect(response).to have_http_status(200)
+    end
+
+    it 'creates a filter' do
+      filter = user.account.custom_filters.first
+      expect(filter).to_not be_nil
+      expect(filter.phrase).to eq 'magic'
+      expect(filter.context).to eq %w(home)
+      expect(filter.irreversible?).to be true
+      expect(filter.expires_at).to be_nil
+    end
+  end
+
+  describe 'GET #show' do
+    let(:filter) { Fabricate(:custom_filter, account: user.account) }
+
+    it 'returns http success' do
+      get :show, params: { id: filter.id }
+      expect(response).to have_http_status(200)
+    end
+  end
+
+  describe 'PUT #update' do
+    let(:filter) { Fabricate(:custom_filter, account: user.account) }
+
+    before do
+      put :update, params: { id: filter.id, phrase: 'updated' }
+    end
+
+    it 'returns http success' do
+      expect(response).to have_http_status(200)
+    end
+
+    it 'updates the filter' do
+      expect(filter.reload.phrase).to eq 'updated'
+    end
+  end
+
+  describe 'DELETE #destroy' do
+    let(:filter) { Fabricate(:custom_filter, account: user.account) }
+
+    before do
+      delete :destroy, params: { id: filter.id }
+    end
+
+    it 'returns http success' do
+      expect(response).to have_http_status(200)
+    end
+
+    it 'removes the filter' do
+      expect { filter.reload }.to raise_error ActiveRecord::RecordNotFound
+    end
+  end
+end