set up RSpec-based test suite and seed with tests

.github/workflows/ci.yml

@@ -0,0 +1,24 @@
+name: CI
+on:
+  push:
+  pull_request:
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+jobs:
+  build:
+    strategy:
+      matrix:
+        os: [ubuntu-latest]
+        ruby: ['2.7', '3.0', '3.1']
+    runs-on: ${{ matrix.os }}
+    steps:
+    - name: Checkout
+      uses: actions/checkout@v2
+    - name: Install Ruby
+      uses: ruby/setup-ruby@v1
+      with:
+        ruby-version: ${{ matrix.ruby }}
+        bundler-cache: true
+    - name: Run tests
+      run: bundle exec rspec

spec/open_uri_cache_spec.rb

@@ -0,0 +1,17 @@
+require_relative 'spec_helper'
+
+describe 'OpenURI::Cache' do
+  subject { OpenURI::Cache }
+
+  it 'should set cache_path to folder in /tmp scoped to uid' do
+    expect(subject.cache_path).to eql %(/tmp/open-uri-#{Process.uid})
+  end
+
+  it 'should allow cache_path to be changed' do
+    old_cache_path = subject.cache_path
+    subject.cache_path = '/tmp/open-uri'
+    expect(subject.cache_path).to eql '/tmp/open-uri'
+  ensure
+    subject.cache_path = old_cache_path
+  end
+end

spec/open_uri_spec.rb

@@ -0,0 +1,47 @@
+require_relative 'spec_helper'
+
+describe 'OpenURI.open_uri' do
+  before do
+    OpenURI::Cache.cache_path = cache_dir
+    FileUtils.rm_r OpenURI::Cache.cache_path, force: true, secure: true
+  end
+
+  it 'should cache calls to OpenURI.open_uri for binary file' do
+    actual = with_local_webserver do |base_url, thr|
+      url = %(#{base_url}/square.png)
+      expect(OpenURI::Cache.get url).to be_nil
+      contents = OpenURI.open_uri(url) {|fd| fd.read }
+      expect(OpenURI.open_uri(url) {|fd| fd.read }).to eql contents
+      expect(thr[:requests].length).to eql 1
+      contents
+    end
+    expected = File.read(fixture_file('square.png'), mode: 'rb')
+    expect(actual).to eql expected
+  end
+
+  it 'should cache calls to OpenURI.open_uri for text file' do
+    actual = with_local_webserver do |base_url, thr|
+      url = %(#{base_url}/square.svg)
+      expect(OpenURI::Cache.get url).to be_nil
+      contents = OpenURI.open_uri(url) {|fd| fd.read }
+      expect(OpenURI.open_uri(url) {|fd| fd.read }).to eql contents
+      expect(thr[:requests].length).to eql 1
+      contents
+    end
+    expected = File.read(fixture_file('square.svg'), mode: 'rb')
+    expect(actual).to eql expected
+  end
+
+  it 'should allow cached URL to be invalidated immediately' do
+    actual = with_local_webserver do |base_url, thr|
+      url = %(#{base_url}/square.png)
+      contents = OpenURI.open_uri(url) {|fd| fd.read }
+      OpenURI::Cache.invalidate url
+      expect(OpenURI.open_uri(url) {|fd| fd.read }).to eql contents
+      expect(thr[:requests].length).to eql 2
+      contents
+    end
+    expected = File.read(fixture_file('square.png'), mode: 'rb')
+    expect(actual).to eql expected
+  end
+end

spec/spec_helper.rb

@@ -6,20 +6,88 @@
 # about re-initializing constants
 $VERBOSE = nil
 
+require 'open-uri/cached'
+require 'fileutils' unless defined? FileUtils
+require 'socket'
 require 'webmock/rspec'
 
 RSpec.configure do |config|
   config.order = :random
   Kernel.srand config.seed
 
-  config.before do
-    WebMock.disable_net_connect!
+  config.before :each do
+    WebMock.disable_net_connect!(allow_localhost: true)
 
     stub_request(:get, 'https://rubygems.org/').to_return(
       status: 200,
       body: File.read(File.expand_path('support/fixtures/rubygems.org.html', __dir__)),
       headers: {}
     )
   end
-end
+
+  config.before :suite do
+    FileUtils.rm_r cache_dir, force: true, secure: true
+  end
+
+  config.after :suite do
+    FileUtils.rm_r cache_dir, force: true, secure: true
+  end
+
+  def cache_dir
+    File.join __dir__, 'cache'
+  end
+
+  def fixtures_dir
+    File.join __dir__, 'fixtures'
+  end
+
+  def fixture_file path
+    File.join fixtures_dir, path
+  end
 
+  def with_local_webserver host = resolve_localhost, port = 9876
+    base_dir = fixtures_dir
+    server = TCPServer.new host, port
+    server_thread = Thread.start do
+      Thread.current[:requests] = requests = []
+      while (session = server.accept)
+        requests << (request = session.gets)
+        if %r/^GET (\S+) HTTP\/1\.1$/ =~ request.chomp
+          resource = (resource = $1) == '' ? '.' : resource
+        else
+          session.print %(HTTP/1.1 405 Method Not Allowed\r\nContent-Type: text/plain\r\n\r\n)
+          session.print %(405 - Method not allowed\r\n)
+          session.close
+          next
+        end
+        resource, _query = resource.split '?', 2 if resource.include? '?'
+        if File.file? (resource_file = (File.join base_dir, resource))
+          if (ext = (File.extname resource_file)[1..-1])
+            mimetype = %(image/#{ext})
+          else
+            mimetype = 'text/plain'
+          end
+          session.print %(HTTP/1.1 200 OK\r\nContent-Type: #{mimetype}\r\n\r\n)
+          File.open resource_file, 'rb:utf-8:utf-8' do |fd|
+            session.write fd.read 256 until fd.eof?
+          end
+        else
+          session.print %(HTTP/1.1 404 Not Found\r\nContent-Type: text/plain\r\n\r\n)
+          session.print %(404 - Resource not found.\r\n)
+        end
+        session.close
+      end
+    end
+    begin
+      yield %(http://#{host}:#{port}), server_thread
+    ensure
+      server_thread.exit
+      server_thread.value
+      server.close
+    end
+  end
+
+  def resolve_localhost
+    Socket.ip_address_list.find(&:ipv4?).ip_address
+  end
+end