Fix ServerManager test stubbing for Open3.capture2

The ServerManager was updated to use Open3.capture2 instead of
backticks for better security, but tests were still stubbing
the old backtick method. Updated tests to match implementation.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

Author: justin808

spec/react_on_rails/dev/server_manager_spec.rb

@@ -2,6 +2,7 @@
 
 require_relative "../spec_helper"
 require "react_on_rails/dev/server_manager"
+require "open3"
 
 RSpec.describe ReactOnRails::Dev::ServerManager do
   # Suppress stdout/stderr during tests
@@ -73,16 +74,14 @@ def mock_system_calls
     end
 
     it "attempts to kill development processes" do
-      # Mock all the pgrep patterns used in kill_processes
-      allow_any_instance_of(Kernel).to receive(:`).with("pgrep -f \"rails\" 2>/dev/null").and_return("1234\n5678")
-      pgrep_cmd = "pgrep -f \"node.*react[-_]on[-_]rails\" 2>/dev/null"
-      allow_any_instance_of(Kernel).to receive(:`).with(pgrep_cmd).and_return("2345")
-      allow_any_instance_of(Kernel).to receive(:`).with("pgrep -f \"overmind\" 2>/dev/null").and_return("")
-      allow_any_instance_of(Kernel).to receive(:`).with("pgrep -f \"foreman\" 2>/dev/null").and_return("")
-      allow_any_instance_of(Kernel).to receive(:`).with("pgrep -f \"ruby.*puma\" 2>/dev/null").and_return("")
-      allow_any_instance_of(Kernel).to receive(:`).with("pgrep -f \"webpack-dev-server\" 2>/dev/null").and_return("")
-      shakapacker_cmd = "pgrep -f \"bin/shakapacker-dev-server\" 2>/dev/null"
-      allow_any_instance_of(Kernel).to receive(:`).with(shakapacker_cmd).and_return("")
+      # Mock Open3.capture2 calls that find_process_pids uses
+      allow(Open3).to receive(:capture2).with("pgrep", "-f", "rails", err: File::NULL).and_return(["1234\n5678", nil])
+      allow(Open3).to receive(:capture2).with("pgrep", "-f", "node.*react[-_]on[-_]rails", err: File::NULL).and_return(["2345", nil])
+      allow(Open3).to receive(:capture2).with("pgrep", "-f", "overmind", err: File::NULL).and_return(["", nil])
+      allow(Open3).to receive(:capture2).with("pgrep", "-f", "foreman", err: File::NULL).and_return(["", nil])
+      allow(Open3).to receive(:capture2).with("pgrep", "-f", "ruby.*puma", err: File::NULL).and_return(["", nil])
+      allow(Open3).to receive(:capture2).with("pgrep", "-f", "webpack-dev-server", err: File::NULL).and_return(["", nil])
+      allow(Open3).to receive(:capture2).with("pgrep", "-f", "bin/shakapacker-dev-server", err: File::NULL).and_return(["", nil])
 
       allow(Process).to receive(:pid).and_return(9999) # Current process PID
       expect(Process).to receive(:kill).with("TERM", 1234)
@@ -93,7 +92,12 @@ def mock_system_calls
     end
 
     it "cleans up socket files when they exist" do
+      # Make sure no processes are found so cleanup_socket_files gets called
+      allow(Open3).to receive(:capture2).and_return(["", nil])
+
       allow(File).to receive(:exist?).with(".overmind.sock").and_return(true)
+      allow(File).to receive(:exist?).with("tmp/sockets/overmind.sock").and_return(false)
+      allow(File).to receive(:exist?).with("tmp/pids/server.pid").and_return(false)
       expect(File).to receive(:delete).with(".overmind.sock")
 
       described_class.kill_processes