RSpec Validates Numericality of Active Record Model with Shoulda Matchers

rspec_validates_numericality_with_shoulda_matchers.rb

# Shared specs for models with the `:validates_numericality_of` validators.
# Usage: pass a hash of each of the symbolized names of each options for the
#  numericality validator. If the option has a value with which to evaluate
#  against, add it as the value of that option hash name.
#  E.g.:
#  `it_behaves_like :validates_numericality_model, :numeric_attr, { greater_than_or_equal_to: 0, only_integer: true }`
RSpec.shared_examples :validates_numericality_model do |attribute_name, options|

  it { is_expected.to validate_numericality_of(attribute_name) }

  if options.key? :greater_than_or_equal_to
    it { is_expected.to allow_value(options[:greater_than_or_equal_to]).for(attribute_name) }
    it { is_expected.not_to allow_value(options[:greater_than_or_equal_to].to_i - 1).for(attribute_name) }
  end

  if options.key? :less_than_or_equal_to
    it { is_expected.to allow_value(options[:less_than_or_equal_to]).for(attribute_name) }
    it { is_expected.not_to allow_value(options[:less_than_or_equal_to].to_i + 1).for(attribute_name) }
  end

  it { is_expected.not_to allow_value(0.5).for(attribute_name) } if options[:only_integer]

  it { is_expected.to allow_value(nil).for(attribute_name) } if options[:allow_nil]

end

This is for expressing the full specification of a data model's attribute when there are many conditions regarding the numerical value of said attr.