chore(ruby): Add CI workflow to run mock server tests

Author: aakashanandg

.github/workflows/ruby-wrapper-tests.yml

@@ -0,0 +1,56 @@
+name: Ruby Wrapper Tests
+
+on:
+  push:
+    branches:
+        - main
+  pull_request:
+
+jobs:
+  test:
+    name: Test ${{ matrix.os }} (Ruby ${{ matrix.ruby-version }})
+    runs-on: ${{ matrix.os }}
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ubuntu-latest, macos-latest]
+        ruby-version: ['3.3']
+
+    defaults:
+      run:
+        shell: bash
+        working-directory: ./spannerlib/wrappers/spannerlib-ruby
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Set up Go
+        uses: actions/setup-go@v5
+        with:
+          go-version: '1.25.x'
+
+      - name: Set up Ruby
+        uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: ${{ matrix.ruby-version }}
+          bundler-cache: true
+          working-directory: ./spannerlib/wrappers/spannerlib-ruby
+
+      - name: Build shared library (Linux)
+        if: runner.os == 'Linux'
+        run: bundle exec rake compile:x86_64-linux
+
+      - name: Build shared library (macOS)
+        if: runner.os == 'macOS'
+        run: |
+          ARCH=$(uname -m)
+          if [ "$ARCH" == "arm64" ]; then
+            bundle exec rake compile:aarch64-darwin
+          else
+            bundle exec rake compile:x86_64-darwin
+          fi
+
+      - name: Run Tests
+        run: |
+          bundle exec ruby -Ilib -Ispec spec/spannerlib_ruby_spec.rb

spannerlib/wrappers/spannerlib-ruby/spec/mock_server_runner.rb

@@ -0,0 +1,40 @@
+# frozen_string_literal: true
+
+# Copyright 2025 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+$stdout.sync = true
+
+require "grpc"
+require "google/cloud/spanner/v1/spanner"
+require "google/spanner/v1/spanner_pb"
+require "google/spanner/v1/spanner_services_pb"
+
+require_relative "mock_server/spanner_mock_server"
+
+begin
+  server = GRPC::RpcServer.new
+  port = server.add_http2_port "127.0.0.1:0", :this_port_is_insecure
+  server.handle SpannerMockServer.new
+
+  # 2. Print ONLY the port number to stdout for the parent to read
+  puts port
+  server.run_till_terminated
+rescue SignalException
+  exit(0)
+rescue StandardError => e
+  warn "Mock server crashed: #{e.message}"
+  warn e.backtrace.join("\n")
+  exit(1)
+end

spannerlib/wrappers/spannerlib-ruby/spec/spannerlib_ruby_spec.rb

@@ -1,5 +1,6 @@
 # frozen_string_literal: true
 
+# rubocop:disable Style/GlobalVars
 # rubocop:disable RSpec/NoExpectationExample
 
 # Copyright 2025 Google LLC
@@ -17,57 +18,97 @@
 # limitations under the License.
 
 require "minitest/autorun"
-
-require "grpc"
-require "google/rpc/error_details_pb"
-require "google/spanner/v1/spanner_pb"
-require "google/spanner/v1/spanner_services_pb"
 require "google/cloud/spanner/v1/spanner"
 
-require_relative "mock_server/statement_result"
-require_relative "mock_server/spanner_mock_server"
-
 require_relative "../lib/spannerlib/ffi"
 require_relative "../lib/spannerlib/connection"
-require_relative "../lib/spannerlib/rows"
-
-READ_PIPE, WRITE_PIPE = IO.pipe
-GRPC.prefork
-
-SERVER_PID = fork do
-  GRPC.postfork_child
-  READ_PIPE.close
-  $stdout.sync = true
-  $stderr.sync = true
-
-  begin
-    server = GRPC::RpcServer.new
-    port = server.add_http2_port "localhost:0", :this_port_is_insecure
-    mock = SpannerMockServer.new
-    server.handle mock
-
-    WRITE_PIPE.puts port
-    WRITE_PIPE.close
-
-    server.run
-  rescue StandardError => e
-    warn "Mock server failed to start: #{e.message}"
-    exit(1)
+
+$server_pid = nil
+$server_port = nil
+
+Minitest.after_run do
+  if $server_pid
+    begin
+      Process.kill("TERM", $server_pid)
+      Process.wait($server_pid)
+    rescue Errno::ESRCH, Errno::ECHILD, Errno::EINVAL
+      # Process already dead or OS rejected the signal; ignore safely.
+    end
   end
 end
 
-GRPC.postfork_parent
-WRITE_PIPE.close
+describe "Connection" do
+  def self.spawn_server
+    runner_path = File.expand_path(File.join(__dir__, "mock_server_runner.rb"))
+    r_log, w_log = IO.pipe
+    cmd = [Gem.ruby, "-Ilib", "-Ispec", runner_path]
+
+    pid = spawn(*cmd, out: w_log, err: %i[child out])
+    w_log.close
+    [pid, r_log]
+  end
 
-SERVER_PORT = READ_PIPE.gets.strip.to_i
-READ_PIPE.close
+  # rubocop:disable Metrics/MethodLength
+  def self.wait_for_port(r_log)
+    unless r_log.wait_readable(20) # 20 second timeout
+      begin
+        Process.kill("TERM", $server_pid)
+      rescue StandardError
+        nil
+      end
+      raise "Timed out waiting for mock server to start."
+    end
 
-describe "Connection" do
-  before do
-    server_address = "localhost:#{SERVER_PORT}"
-    database_path = "projects/p/instances/i/databases/d"
+    line = r_log.gets
+    if line.nil?
+      Process.wait($server_pid)
+      raise "Mock server exited early. Exit code: #{$CHILD_STATUS.exitstatus}"
+    end
 
-    @dsn = "#{server_address}/#{database_path}?useplaintext=true"
+    port = line.strip.to_i
+    if port <= 0
+      remaining_output = begin
+        r_log.read_nonblock(4096)
+      rescue StandardError
+        ""
+      end
+      raise "Mock server failed to start.\nOutput:\n#{line}#{remaining_output}"
+    end
+
+    port
+  end
+
+  def self.ensure_server_running!
+    return if $server_port
+
+    $server_pid, r_log = spawn_server
+
+    begin
+      $server_port = wait_for_port(r_log)
+      # CRITICAL: Drain sub-process output in a background thread to prevent
+      # the pipe buffer from filling up and hanging the server.
+      Thread.new { while r_log.gets; end }
+    rescue StandardError
+      if $server_pid
+        begin
+          Process.kill("TERM", $server_pid)
+        rescue StandardError
+          nil
+        end
+        begin
+          Process.wait($server_pid)
+        rescue StandardError
+          nil
+        end
+      end
+      raise
+    end
+  end
+  # rubocop:enable Metrics/MethodLength
+
+  before do
+    self.class.ensure_server_running!
+    @dsn = "127.0.0.1:#{$server_port}/projects/p/instances/i/databases/d?useplaintext=true"
 
     @pool_id = SpannerLib.create_pool(@dsn)
     @conn_id = SpannerLib.create_connection(@pool_id)
@@ -108,13 +149,5 @@
     _(commit_resp.commit_timestamp).wont_be_nil
   end
 end
-
 # rubocop:enable RSpec/NoExpectationExample
-
-# --- 5. GLOBAL SHUTDOWN HOOK ---
-Minitest.after_run do
-  if SERVER_PID
-    Process.kill("KILL", SERVER_PID)
-    Process.wait(SERVER_PID)
-  end
-end
+# rubocop:enable Style/GlobalVars