Model validations

test/models/mat_test.rb

@@ -4,4 +4,10 @@ class MatTest < ActiveSupport::TestCase
  test "the truth" do
      assert true
    end
+   
+   test "Mat validations" do
+      mat = Mat.new
+      assert_not mat.valid?
+      assert_equal [:name], mat.errors.keys
+    end
 end