Convert specs to RSpec 2.99.0 syntax with Transpec

Convert specs to RSpec 2.99.0 syntax with Transpec

This conversion is done by Transpec 2.2.1 with the following command:
    transpec spec/unit

* 53 conversions
    from: obj.should
      to: expect(obj).to

* 19 conversions
    from: == expected
      to: eq(expected)

* 5 conversions
    from: lambda { }.should
      to: expect { }.to

* 2 conversions
    from: be_true
      to: be_truthy

For more details: https://github.com/yujinakayama/transpec#supported-conversions