Add unit tests for encrypted token authenticatable

app/models/concerns/token_authenticatable_strategies/base.rb

 # frozen_string_literal: true
 
 module TokenAuthenticatableStrategies
-  attr_reader :klass, :token_field, :options
-
   class Base
+    attr_reader :klass, :token_field, :options
+
     def initialize(klass, token_field, options)
       @klass = klass
       @token_field = token_field

spec/models/concerns/token_authenticatable_strategies/encrypted_spec.rb

@@ -2,18 +2,69 @@ require 'spec_helper'
 
 describe TokenAuthenticatableStrategies::Encrypted do
   let(:model) { double(:model) }
+  let(:instance) { double(:instance) }
   let(:options) { { fallback: true } }
 
+  let(:encrypted) do
+    Gitlab::CryptoHelper.aes256_gcm_encrypt('my-value')
+  end
+
   subject do
     described_class.new(model, 'some_field', options)
   end
 
   describe '#find_token_authenticatable' do
+    it 'finds a relevant resource by encrypted value' do
+      allow(model).to receive(:find_by)
+        .with('some_field_encrypted' => encrypted)
+        .and_return('encrypted resource')
+
+      expect(subject.find_token_authenticatable('my-value'))
+        .to eq 'encrypted resource'
+    end
+
+    it 'uses fallback strategy when token can not be found' do
+      allow_any_instance_of(TokenAuthenticatableStrategies::Insecure)
+        .to receive(:find_token_authenticatable)
+        .and_return('plaintext resource')
+
+      allow(model).to receive(:find_by)
+        .with('some_field_encrypted' => encrypted)
+        .and_return(nil)
+
+      expect(subject.find_token_authenticatable('my-value'))
+        .to eq 'plaintext resource'
+    end
   end
 
   describe '#get_token' do
+    it 'decrypts a token when encrypted token is present' do
+      allow(instance).to receive(:read_attribute)
+        .with('some_field_encrypted')
+        .and_return(encrypted)
+
+      expect(subject.get_token(instance)).to eq 'my-value'
+    end
+
+    it 'reads a plaintext token when encrypted token is not present' do
+      allow(instance).to receive(:read_attribute)
+        .with('some_field_encrypted')
+        .and_return(nil)
+
+      allow(instance).to receive(:read_attribute)
+        .with('some_field')
+        .and_return('cleartext value')
+
+      expect(subject.get_token(instance)).to eq 'cleartext value'
+    end
   end
 
   describe '#set_token' do
+    it 'writes encrypted token to a model instance' do
+      expect(instance).to receive(:[]=)
+        .with('some_field_encrypted', encrypted)
+
+      subject.set_token(instance, 'my-value')
+    end
   end
 end