test: add tests for Server model

spec/models/user_spec.rb

@@ -0,0 +1,36 @@
+# frozen_string_literal: true
+
+require "rails_helper"
+
+describe User do
+  context "model" do
+    subject(:user) { create(:user) }
+
+    it "should have a UUID" do
+      expect(user.uuid).to be_a String
+      expect(user.uuid.length).to eq 36
+    end
+  end
+
+  context ".authenticate" do
+    it "should not authenticate users with invalid emails" do
+      expect { User.authenticate("nothing@nothing.com", "hello") }.to raise_error(Postal::Errors::AuthenticationError) do |e|
+        expect(e.error).to eq "InvalidEmailAddress"
+      end
+    end
+
+    it "should not authenticate users with invalid passwords" do
+      user = create(:user)
+      expect { User.authenticate(user.email_address, "hello") }.to raise_error(Postal::Errors::AuthenticationError) do |e|
+        expect(e.error).to eq "InvalidPassword"
+      end
+    end
+
+    it "should authenticate valid users" do
+      user = create(:user)
+      auth_user = nil
+      expect { auth_user = User.authenticate(user.email_address, "passw0rd") }.to_not raise_error
+      expect(auth_user).to eq user
+    end
+  end
+end