[rb] make flaky unit tests hermetic

Author: titusfortner

rb/spec/unit/selenium/server_spec.rb

@@ -108,7 +108,7 @@ module Selenium
               'bar')
         .and_return(mock_process)
 
-      server = described_class.new('selenium_server_deploy.jar', background: true)
+      server = described_class.new('selenium_server_deploy.jar', port: port, background: true)
       allow(server).to receive_messages(socket: mock_poller, status_ok?: true)
 
       server << %w[foo bar]
@@ -200,7 +200,7 @@ module Selenium
       poller = instance_double(WebDriver::SocketPoller)
       allow(poller).to receive(:connected?).and_return(false)
 
-      server = described_class.new('selenium_server_deploy.jar', background: true)
+      server = described_class.new('selenium_server_deploy.jar', port: port, background: true)
       allow(server).to receive(:socket).and_return(poller)
 
       expect { server.start }.to raise_error(Selenium::Server::Error)

rb/spec/unit/selenium/webdriver/socket_poller_spec.rb

@@ -23,16 +23,26 @@ module Selenium
   module WebDriver
     describe SocketPoller do
       before(:context) do
-        @server_thread = Thread.new do
-          server = TCPServer.open(Platform.localhost, 9250)
-          Thread.current.thread_variable_set(:server, server)
-          loop { server.accept.close }
+        # Open the listening socket synchronously so the server object is captured
+        # deterministically (no race with the accept thread) and bind errors surface here.
+        @listening_server = TCPServer.new(Platform.localhost, 0)
+        @listening_port = @listening_server.addr[1]
+        @accept_thread = Thread.new do
+          loop { @listening_server.accept.close }
+        rescue IOError, Errno::EBADF, Errno::ECONNABORTED
+          # listening socket closed during teardown
         end
-        @server_thread.report_on_exception = false
+        @accept_thread.report_on_exception = false
+
+        # Reserve an ephemeral port, then release it so nothing is listening on it.
+        closed_server = TCPServer.new(Platform.localhost, 0)
+        @closed_port = closed_server.addr[1]
+        closed_server.close
       end
 
       after(:context) do
-        @server_thread.thread_variable_get(:server).close
+        @listening_server&.close
+        @accept_thread&.kill
       end
 
       def poller(port)
@@ -41,7 +51,7 @@ def poller(port)
 
       describe '#connected?' do
         it 'returns true when the socket is listening' do
-          expect(poller(9250)).to be_connected
+          expect(poller(@listening_port)).to be_connected
         end
 
         it 'returns false if the socket is not listening after the given timeout' do
@@ -50,13 +60,13 @@ def poller(port)
           stop  = Time.parse('2010-01-01 00:00:06')
 
           allow(Process).to receive(:clock_gettime).and_return(start, wait, stop)
-          expect(poller(9251)).not_to be_connected
+          expect(poller(@closed_port)).not_to be_connected
         end
       end
 
       describe '#closed?' do
         it 'returns true when the socket is closed' do
-          expect(poller(9251)).to be_closed
+          expect(poller(@closed_port)).to be_closed
         end
 
         it 'returns false if the socket is still listening after the given timeout' do
@@ -65,7 +75,7 @@ def poller(port)
           stop  = Time.parse('2010-01-01 00:00:06').to_f
 
           allow(Process).to receive(:clock_gettime).and_return(start, wait, stop)
-          expect(poller(9250)).not_to be_closed
+          expect(poller(@listening_port)).not_to be_closed
         end
       end
     end

rb/spec/unit/selenium/webdriver/zipper_spec.rb

@@ -24,7 +24,8 @@ module WebDriver
     describe Zipper do
       let(:base_file_name) { 'file.txt' }
       let(:file_content)   { 'content' }
-      let(:zip_file)       { File.join(Dir.tmpdir, 'test.zip') }
+      let(:tmp_dir)        { Dir.mktmpdir('webdriver-spec-zip') }
+      let(:zip_file)       { File.join(tmp_dir, 'test.zip') }
       let(:dir_to_zip)     { Dir.mktmpdir('webdriver-spec-zipper') }
 
       def create_file
@@ -34,7 +35,7 @@ def create_file
         filename
       end
 
-      after { FileUtils.rm_rf zip_file }
+      after { FileUtils.rm_rf tmp_dir }
 
       describe '#zip' do
         it 'a file' do
@@ -59,7 +60,6 @@ def create_file
           filename = create_file
           File.symlink(filename, File.join(dir_to_zip, 'link'))
 
-          zip_file = File.join(Dir.tmpdir, 'test.zip')
           File.open(zip_file, 'wb') do |io|
             io << Base64.decode64(described_class.zip(dir_to_zip))
           end