Add OAuth2 authentication (#147)

- Added Site settings > Authentication section
- Create/edit/delete your custom oauth2 configurations
- Login or signup with oauth2

spec/models/o_auth_spec.rb

@@ -0,0 +1,64 @@
+require 'rails_helper'
+
+RSpec.describe OAuth, type: :model do
+  let(:o_auth) { FactoryBot.create(:o_auth) }
+
+  it 'should be valid' do
+    expect(o_auth).to be_valid
+  end
+
+  it 'has a non-nil unique name' do
+    o_auth2 = FactoryBot.build_stubbed(:o_auth, name: o_auth.name)
+
+    expect(o_auth2).to be_invalid
+  end
+
+  it 'is disabled by default' do
+    o_auth = OAuth.new
+
+    expect(o_auth.is_enabled).to eq(false)
+  end
+
+  it 'has a boolean enabled status' do
+    o_auth = FactoryBot.build_stubbed(:o_auth, is_enabled: nil)
+    expect(o_auth).to be_invalid
+
+    o_auth = FactoryBot.build_stubbed(:o_auth, is_enabled: true)
+    expect(o_auth).to be_valid
+
+    o_auth = FactoryBot.build_stubbed(:o_auth, is_enabled: false)
+    expect(o_auth).to be_valid
+  end
+
+  it 'has non-nil client credentials' do
+    o_auth = FactoryBot.build_stubbed(:o_auth, client_id: nil)
+    expect(o_auth).to be_invalid
+
+    o_auth = FactoryBot.build_stubbed(:o_auth, client_secret: nil)
+    expect(o_auth).to be_invalid
+  end
+
+  it 'has non-nil urls' do
+    o_auth = FactoryBot.build_stubbed(:o_auth, authorize_url: nil)
+    expect(o_auth).to be_invalid
+
+    o_auth = FactoryBot.build_stubbed(:o_auth, token_url: nil)
+    expect(o_auth).to be_invalid
+
+    o_auth = FactoryBot.build_stubbed(:o_auth, profile_url: nil)
+    expect(o_auth).to be_invalid
+  end
+
+  it 'has a non-nil scope' do
+    o_auth = FactoryBot.build_stubbed(:o_auth, scope: nil)
+    expect(o_auth).to be_invalid
+  end
+
+  it 'has a non-nil json user email path and a nullable name path' do
+    o_auth = FactoryBot.build_stubbed(:o_auth, json_user_email_path: nil)
+    expect(o_auth).to be_invalid
+
+    o_auth = FactoryBot.build_stubbed(:o_auth, json_user_name_path: nil)
+    expect(o_auth).to be_valid
+  end
+end