Rspec CSV import feature testing with CSV foreach stubbing

csv_importable.rb

# Implementation

module CSVImportable
  extend ActiveSupport::Concern

  included do
    def self.import(file)
      CSV.foreach(file.path, headers: true, encoding:'utf-8') do |row|
        self.create! row.to_hash
      end
    end
  end

end

csv_importable_example.rb

# Spec 
shared_examples_for "csv_importable" do
  describe ".import" do
    context "file structure matches table schema" do
      it "creates table rows with csv rows" do
        file = instance_double(File)
        csv_file = build_csv(described_class.column_names, 3)
        allow(file).to receive(:path)
        allow(File).to receive(:open).and_return(csv_file)
        expect { described_class.import(file) }.to change { described_class.all.size }.by(3)
      end
    end

    context "file structure does not match table schema" do
      it "raise error" do
        file = instance_double(File)
        csv_file = build_csv(described_class.column_names << "excluded_attribute", 3)
        allow(file).to receive(:path)
        allow(File).to receive(:open).and_return(csv_file)
        expect { described_class.import(file) }.to raise_error(ActiveRecord::UnknownAttributeError)
      end
    end
  end

  def build_csv(column_name_array, row_amount = 3)
    CSV.generate do |csv|
      csv << column_name_array
      (1..row_amount).each do |value|
        csv << CSV::Row.new(column_name_array, Array.new(column_name_array.size, value.to_s))
      end
    end
  end

  def generate_csv_rows(column_name_array, row_amount = 3)
    rows = []
    (1..row_amount).each do |value|
      rows << CSV::Row.new(column_name_array, Array.new(column_name_array.size, value.to_s))
    end
    return rows
  end
end

inflections.rb

ActiveSupport::Inflector.inflections(:en) do |inflect|
  inflect.acronym 'CSV'
end