before_user_spec.rb

RSpec.describe User do
  it "should be valid if it's the correct parameters" do
    expect(build(:user)).to be_valid
  end

  context "when screen_name is not present" do
    before { @user = build(:user, screen_name: "") }

    it "should not be valid" do
      expect(@user).not_to be_valid
    end
  end

  context "when screen_name exceeds 15 characters" do
    before { @user = build(:user, screen_name: "c" * 16) }

    it "should not be valid" do
      expect(@user).not_to be_valid
    end
  end

  context "when name is not present" do
    before { @user = build(:user, name: "") }

    it "should not be valid" do
      expect(@user).not_to be_valid
    end
  end
end