Add email validator spec

#186

spec/lib/validators/email_validator_spec.rb

@@ -0,0 +1,23 @@
+require 'spec_helper'
+
+RSpec.describe EmailValidator do
+  describe '#valid?' do
+    subject(:valid) { described_class.new(email).valid? }
+
+    context 'when email is valid' do
+      let(:email) { 'test@test.com' }
+
+      it 'returns truthy' do
+        expect(valid).to be_truthy
+      end
+    end
+
+    context 'when email is invalid' do
+      let(:email) { 'invalid' }
+
+      it 'returns falsey' do
+        expect(valid).to be_falsey
+      end
+    end
+  end
+end