Create fake model for session

test/models/session_test.rb

@@ -0,0 +1,25 @@
+require "test_helper"
+
+class SessionTest < ActiveSupport::TestCase
+  def test_save_when_exists
+    user = users(:one)
+
+    session = Session.new(email: user.email, password: "secret")
+
+    assert session.save
+  end
+
+  def test_save_when_not_exists
+    session = Session.new(email: "fake@example.org", password: "secret")
+
+    refute session.save
+  end
+
+  def test_save_when_password_incorrect
+    user = users(:one)
+
+    session = Session.new(email: user.email, password: "bad_password")
+
+    refute session.save
+  end
+end