[rb] Support remote debugging via debug gem

Author: p0deje

README.md

@@ -268,6 +268,16 @@ To run with a specific version of Ruby you can change the version in `rb/ruby_ve
 echo 'RUBY_VERSION = "<X.Y.Z>"' > rb/ruby_version.bzl
 ```
 
+If you want to debug code in tests, you can do it via [`debug`](https://github.com/ruby/debug) gem:
+
+1. Add `binding.break` to the code where you want the debugger to start.
+2. Run `bazel test --test_output streamed <test>`. Streaming output is not required, but will clearly say when debugger starts.
+3. When debugger starts, run the following in a separate terminal to connect to debugger:
+
+```sh
+bazel-selenium/external/bundle/bin/rdbg -A
+```
+
 If you want to use RubyMine for development, a bit of extra configuration is necessary to let the IDE know about Bazel toolchain and artifacts:
 
 1. Run `bazel build @bundle//:bundle //rb:selenium-devtools //rb:selenium-webdriver` before configuring IDE.

rb/Gemfile.lock

@@ -17,9 +17,16 @@ GEM
     coderay (1.1.3)
     crack (0.4.5)
       rexml
+    debug (1.7.2)
+      irb (>= 1.5.0)
+      reline (>= 0.3.1)
     diff-lcs (1.5.0)
     ffi (1.15.5-java)
     hashdiff (1.0.1)
+    io-console (0.6.0)
+    io-console (0.6.0-java)
+    irb (1.6.4)
+      reline (>= 0.3.0)
     json (2.6.3)
     json (2.6.3-java)
     method_source (1.0.0)
@@ -37,6 +44,8 @@ GEM
     rack (2.2.5)
     rainbow (3.1.1)
     regexp_parser (2.6.1)
+    reline (0.3.3)
+      io-console (~> 0.5)
     rexml (3.2.5)
     rspec (3.12.0)
       rspec-core (~> 3.12.0)
@@ -89,6 +98,7 @@ PLATFORMS
   x64-mingw32
 
 DEPENDENCIES
+  debug (~> 1.7)
   pry (~> 0.14)
   rack (~> 2.0)
   rspec (~> 3.0)

rb/selenium-webdriver.gemspec

@@ -53,6 +53,7 @@ Gem::Specification.new do |s|
   s.add_runtime_dependency 'rubyzip', ['>= 1.2.2', '< 3.0']
   s.add_runtime_dependency 'websocket', ['~> 1.0']
 
+  s.add_development_dependency 'debug', ['~> 1.7']
   s.add_development_dependency 'pry', ['~> 0.14']
   s.add_development_dependency 'rack', ['~> 2.0']
   s.add_development_dependency 'rspec', ['~> 3.0']

rb/spec/integration/selenium/webdriver/spec_helper.rb

@@ -17,6 +17,10 @@
 # specific language governing permissions and limitations
 # under the License.
 
+require 'debug/session'
+DEBUGGER__::CONFIG[:fork_mode] = :parent
+DEBUGGER__.open(nonstop: true)
+
 require 'rubygems'
 require 'time'
 require 'rspec'

rb/spec/unit/selenium/webdriver/common/selenium_manager_spec.rb

@@ -22,31 +22,33 @@
 module Selenium
   module WebDriver
     describe SeleniumManager do
-      describe 'self.binary' do
+      describe '.binary' do
+        def stub_binary(binary)
+          allow(File).to receive(:exist?).with(a_string_ending_with(binary)).and_return(true)
+          allow(File).to receive(:executable?).with(a_string_ending_with(binary)).and_return(true)
+        end
+
         before do
           described_class.instance_variable_set(:@binary, nil)
         end
 
         it 'detects Windows' do
-          allow(File).to receive(:exist?).and_return(true)
-          allow(File).to receive(:executable?).and_return(true)
+          stub_binary('/windows/selenium-manager.exe')
           allow(Platform).to receive(:windows?).and_return(true)
 
           expect(described_class.send(:binary)).to match(%r{/windows/selenium-manager\.exe$})
         end
 
         it 'detects Mac' do
-          allow(File).to receive(:exist?).and_return(true)
-          allow(File).to receive(:executable?).and_return(true)
+          stub_binary('/macos/selenium-manager')
           allow(Platform).to receive(:windows?).and_return(false)
           allow(Platform).to receive(:mac?).and_return(true)
 
           expect(described_class.send(:binary)).to match(%r{/macos/selenium-manager$})
         end
 
         it 'detects Linux' do
-          allow(File).to receive(:exist?).and_return(true)
-          allow(File).to receive(:executable?).and_return(true)
+          stub_binary('/linux/selenium-manager')
           allow(Platform).to receive(:windows?).and_return(false)
           allow(Platform).to receive(:mac?).and_return(false)
           allow(Platform).to receive(:linux?).and_return(true)
@@ -55,7 +57,7 @@ module WebDriver
         end
 
         it 'errors if cannot find' do
-          allow(File).to receive(:exist?).and_return(false)
+          allow(File).to receive(:exist?).with(a_string_including('selenium-manager')).and_return(false)
 
           expect {
             described_class.send(:binary)

rb/spec/unit/selenium/webdriver/spec_helper.rb

@@ -17,6 +17,10 @@
 # specific language governing permissions and limitations
 # under the License.
 
+require 'debug/session'
+DEBUGGER__::CONFIG[:fork_mode] = :parent
+DEBUGGER__.open(nonstop: true)
+
 require 'rubygems'
 require 'time'
 require 'rspec'
@@ -48,4 +52,9 @@ def with_env(hash)
   c.include Selenium::WebDriver::UnitSpecHelper
 
   c.filter_run focus: true if ENV['focus']
+
+  c.before do
+    # https://github.com/ruby/debug/issues/797
+    allow(File).to receive(:exist?).and_call_original
+  end
 end