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Validating Attachment Size Constraints in Paperclip

This test suite validates attachment size constraints in the Paperclip gem, focusing on file size validation functionality. It ensures proper handling of size limits, conditional validations, and post-processing behavior for file attachments.

Test Coverage Overview

The test suite comprehensively covers attachment size validation scenarios in Paperclip:

Size range validation (256..1024 bytes)
Upper and lower limit validations
Conditional validation using :if controls
Post-processing behavior verification

Implementation Analysis

The testing approach utilizes RSpec’s describe/context/it blocks for structured test organization. It implements Paperclip’s Shoulda matchers for validation testing, with specific focus on ValidateAttachmentSizeMatcher functionality.

The tests use mock objects and expectations to verify behavior without actual file processing.

Technical Details

Testing components include:

RSpec as the testing framework
Paperclip::Shoulda::Matchers for validation assertions
Database table reset helpers for test isolation
Mock objects for file attachment simulation

Best Practices Demonstrated

The test suite exemplifies several testing best practices:

Isolated test contexts with proper setup/teardown
Clear test case organization
Comprehensive edge case coverage
Efficient use of helper methods and shared setup

thoughtbot/paperclip

spec/paperclip/matchers/validate_attachment_size_matcher_spec.rb

            
require 'spec_helper'
require 'paperclip/matchers'

describe Paperclip::Shoulda::Matchers::ValidateAttachmentSizeMatcher do
  extend Paperclip::Shoulda::Matchers

  before do
    reset_table("dummies") do |d|
      d.string :avatar_file_name
      d.bigint :avatar_file_size
    end
    reset_class "Dummy"
    Dummy.do_not_validate_attachment_file_type :avatar
    Dummy.has_attached_file :avatar
  end

  context "Limiting size" do
    it "rejects a class with no validation" do
      expect(matcher.in(256..1024)).to_not accept(Dummy)
    end

    it "rejects a class with a validation that's too high" do
      Dummy.validates_attachment_size :avatar, in: 256..2048
      expect(matcher.in(256..1024)).to_not accept(Dummy)
    end

    it "accepts a class with a validation that's too low" do
      Dummy.validates_attachment_size :avatar, in: 0..1024
      expect(matcher.in(256..1024)).to_not accept(Dummy)
    end

    it "accepts a class with a validation that matches" do
      Dummy.validates_attachment_size :avatar, in: 256..1024
      expect(matcher.in(256..1024)).to accept(Dummy)
    end
  end

  context "allowing anything" do
    it "given a class with an upper limit" do
      Dummy.validates_attachment_size :avatar, less_than: 1
      expect(matcher).to accept(Dummy)
    end

    it "given a class with a lower limit" do
      Dummy.validates_attachment_size :avatar, greater_than: 1
      expect(matcher).to accept(Dummy)
    end
  end

  context "using an :if to control the validation" do
    before do
      Dummy.class_eval do
        validates_attachment_size :avatar, greater_than: 1024, if: :go
        attr_accessor :go
      end
    end

    it "run the validation if the control is true" do
      dummy = Dummy.new
      dummy.go = true
      expect(matcher.greater_than(1024)).to accept(dummy)
    end

    it "not run the validation if the control is false" do
      dummy = Dummy.new
      dummy.go = false
      expect(matcher.greater_than(1024)).to_not accept(dummy)
    end
  end

  context "post processing" do
    before do
      Dummy.validates_attachment_size :avatar, greater_than: 1024
    end

    it "be skipped" do
      dummy = Dummy.new
      dummy.avatar.expects(:post_process).never
      expect(matcher.greater_than(1024)).to accept(dummy)
    end
  end

  private

  def matcher
    self.class.validate_attachment_size(:avatar)
  end
end