Guard specs needing #fork with guard -> { Process.respond_to?(:fork) } do

core/io/foreach_spec.rb

@@ -28,7 +28,7 @@
         ScratchPad.recorded.should == ["hello\n", "line2\n"]
       end
 
-      platform_is_not :windows do
+      guard -> { Process.respond_to?(:fork) } do
         it "gets data from a fork when passed -" do
           parent_pid = $$
 

core/io/read_spec.rb

@@ -163,7 +163,7 @@
       end
     end
 
-    platform_is_not :windows do
+    guard -> { Process.respond_to?(:fork) } do
       it "opens a pipe to a fork if the rest is -" do
         str = nil
         suppress_warning do # https://bugs.ruby-lang.org/issues/19630

core/io/readlines_spec.rb

@@ -189,7 +189,7 @@
         lines.should == ["hello\n", "line2\n"]
       end
 
-      platform_is_not :windows do
+      guard -> { Process.respond_to?(:fork) } do
         it "gets data from a fork when passed -" do
           lines = nil
           suppress_warning do # https://bugs.ruby-lang.org/issues/19630

core/process/daemon_spec.rb

@@ -1,10 +1,11 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/common'
 
-platform_is_not :windows do
-  # macOS 15 is not working this examples
-  return if /darwin/ =~ RUBY_PLATFORM && /15/ =~ `sw_vers -productVersion`
-
+guard -> {
+  Process.respond_to?(:fork) and
+    # macOS 15 is not working for these examples
+    !(/darwin/ =~ RUBY_PLATFORM && /15/ =~ `sw_vers -productVersion`)
+} do
   describe :process_daemon_keep_stdio_open_false, shared: true do
     it "redirects stdout to /dev/null" do
       @daemon.invoke("keep_stdio_open_false_stdout", @object).should == ""
@@ -107,8 +108,12 @@
   end
 end
 
-platform_is :windows do
+guard_not -> { Process.respond_to?(:fork) } do
   describe "Process.daemon" do
+    it "returns false from #respond_to?" do
+      Process.respond_to?(:daemon).should == false
+    end
+
     it "raises a NotImplementedError" do
       -> {
         Process.daemon

core/process/detach_spec.rb

@@ -1,81 +1,82 @@
 require_relative '../../spec_helper'
+require_relative 'fixtures/common'
 
 describe "Process.detach" do
-  platform_is_not :windows do
-    it "returns a thread" do
-      pid = Process.fork { Process.exit! }
-      thr = Process.detach(pid)
-      thr.should.is_a?(Thread)
-      thr.join
-    end
+  ProcessSpecs.use_system_ruby(self)
 
-    it "produces the exit Process::Status as the thread value" do
-      pid = Process.fork { Process.exit! }
-      thr = Process.detach(pid)
-      thr.join
+  it "returns a thread" do
+    pid = Process.spawn(*ruby_exe, "-e", "exit")
+    thr = Process.detach(pid)
+    thr.should.is_a?(Thread)
+    thr.join
+  end
 
-      status = thr.value
-      status.should.is_a?(Process::Status)
-      status.pid.should == pid
-    end
+  it "produces the exit Process::Status as the thread value" do
+    pid = Process.spawn(*ruby_exe, "-e", "exit")
+    thr = Process.detach(pid)
+    thr.join
+
+    status = thr.value
+    status.should.is_a?(Process::Status)
+    status.pid.should == pid
+  end
 
-    platform_is_not :openbsd do
-      it "reaps the child process's status automatically" do
-        pid = Process.fork { Process.exit! }
-        Process.detach(pid).join
-        -> { Process.waitpid(pid) }.should.raise(Errno::ECHILD)
-      end
+  platform_is_not :openbsd do
+    it "reaps the child process's status automatically" do
+      pid = Process.spawn(*ruby_exe, "-e", "exit")
+      Process.detach(pid).join
+      -> { Process.waitpid(pid) }.should.raise(Errno::ECHILD)
     end
+  end
 
-    it "sets the :pid thread-local to the PID" do
-      pid = Process.fork { Process.exit! }
-      thr = Process.detach(pid)
-      thr.join
+  it "sets the :pid thread-local to the PID" do
+    pid = Process.spawn(*ruby_exe, "-e", "exit")
+    thr = Process.detach(pid)
+    thr.join
 
-      thr[:pid].should == pid
-    end
+    thr[:pid].should == pid
+  end
 
-    it "provides a #pid method on the returned thread which returns the PID" do
-      pid = Process.fork { Process.exit! }
-      thr = Process.detach(pid)
-      thr.join
+  it "provides a #pid method on the returned thread which returns the PID" do
+    pid = Process.spawn(*ruby_exe, "-e", "exit")
+    thr = Process.detach(pid)
+    thr.join
 
-      thr.pid.should == pid
-    end
+    thr.pid.should == pid
+  end
 
-    it "tolerates not existing child process pid" do
-      # Use a value that is close to the INT_MAX (pid usually is signed int).
-      # It should (at least) be greater than allowed pid limit value that depends on OS.
-      pid_not_existing = 2.pow(30)
+  it "tolerates not existing child process pid" do
+    # Use a value that is close to the INT_MAX (pid usually is signed int).
+    # It should (at least) be greater than allowed pid limit value that depends on OS.
+    pid_not_existing = 2.pow(30)
 
-      # Check that there is no a child process with this hardcoded pid.
-      # Command `kill 0 pid`:
-      # - returns "1" if a process exists and
-      # - raises Errno::ESRCH otherwise
-      -> {  Process.kill(0, pid_not_existing) }.should.raise(Errno::ESRCH)
+    # Check that there is no a child process with this hardcoded pid.
+    # Command `kill 0 pid`:
+    # - returns "1" if a process exists and
+    # - raises Errno::ESRCH otherwise
+    -> {  Process.kill(0, pid_not_existing) }.should.raise(Errno::ESRCH)
 
-      thr = Process.detach(pid_not_existing)
-      thr.join
+    thr = Process.detach(pid_not_existing)
+    thr.join
 
-      thr.should.is_a?(Thread)
-    end
+    thr.should.is_a?(Thread)
+  end
 
-    it "calls #to_int to implicitly convert non-Integer pid to Integer" do
-      pid = MockObject.new('mock-enumerable')
-      pid.should_receive(:to_int).and_return(100500)
+  it "calls #to_int to implicitly convert non-Integer pid to Integer" do
+    pid = MockObject.new('mock-enumerable')
+    pid.should_receive(:to_int).and_return(100500)
 
-      Process.detach(pid).join
-    end
+    Process.detach(pid).join
+  end
 
-    it "raises TypeError when pid argument does not have #to_int method" do
-      -> { Process.detach(Object.new) }.should.raise(TypeError, "no implicit conversion of Object into Integer")
-    end
+  it "raises TypeError when pid argument does not have #to_int method" do
+    -> { Process.detach(Object.new) }.should.raise(TypeError, "no implicit conversion of Object into Integer")
+  end
 
-    it "raises TypeError when #to_int returns non-Integer value" do
-      pid = MockObject.new('mock-enumerable')
-      pid.should_receive(:to_int).and_return(:symbol)
+  it "raises TypeError when #to_int returns non-Integer value" do
+    pid = MockObject.new('mock-enumerable')
+    pid.should_receive(:to_int).and_return(:symbol)
 
-      -> { Process.detach(pid) }.should raise_consistent_error(TypeError, "can't convert MockObject into Integer (MockObject#to_int gives Symbol)")
-    end
+    -> { Process.detach(pid) }.should raise_consistent_error(TypeError, "can't convert MockObject into Integer (MockObject#to_int gives Symbol)")
   end
 end

core/process/setpgid_spec.rb

@@ -1,7 +1,7 @@
 require_relative '../../spec_helper'
 
 describe "Process.setpgid" do
-  platform_is_not :windows do
+  guard -> { Process.respond_to?(:fork) } do
     # Must use fork as setpgid(2) gives EACCESS after execve()
     it "sets the process group id of the specified process" do
       rd, wr = IO.pipe

core/process/setpgrp_spec.rb

@@ -2,7 +2,7 @@
 
 # TODO: put these in the right files.
 describe "Process.setpgrp and Process.getpgrp" do
-  platform_is_not :windows do
+  guard -> { Process.respond_to?(:fork) } do
     it "sets and gets the process group ID of the calling process" do
       # there are two synchronization points here:
       # One for the child to let the parent know that it has finished

core/process/status/wait_spec.rb

@@ -70,25 +70,27 @@
     end
 
     # This spec is probably system-dependent.
-    it "doesn't block if no child is available when WNOHANG is used" do
-      read, write = IO.pipe
-      pid = Process.fork do
-        read.close
-        Signal.trap("TERM") { Process.exit! }
-        write << 1
+    guard -> { Process.respond_to?(:fork) } do
+      it "doesn't block if no child is available when WNOHANG is used" do
+        read, write = IO.pipe
+        pid = Process.fork do
+          read.close
+          Signal.trap("TERM") { Process.exit! }
+          write << 1
+          write.close
+          sleep
+        end
+
+        Process::Status.wait(pid, Process::WNOHANG).should == nil
+
+        # wait for the child to setup its TERM handler
         write.close
-        sleep
-      end
-
-      Process::Status.wait(pid, Process::WNOHANG).should == nil
-
-      # wait for the child to setup its TERM handler
-      write.close
-      read.read(1)
-      read.close
+        read.read(1)
+        read.close
 
-      Process.kill("TERM", pid)
-      Process::Status.wait.pid.should == pid
+        Process.kill("TERM", pid)
+        Process::Status.wait.pid.should == pid
+      end
     end
 
     it "always accepts flags=0" do

core/process/wait2_spec.rb

@@ -1,6 +1,9 @@
 require_relative '../../spec_helper'
+require_relative 'fixtures/common'
 
 describe "Process.wait2" do
+  ProcessSpecs.use_system_ruby(self)
+
   before :all do
     # HACK: this kludge is temporarily necessary because some
     # misbehaving spec somewhere else does not clear processes
@@ -18,15 +21,13 @@
     end
   end
 
-  platform_is_not :windows do
-    it "returns the pid and status of child process" do
-      pidf = Process.fork { Process.exit! 99 }
-      results = Process.wait2
-      results.size.should == 2
-      pidw, status = results
-      pidf.should == pidw
-      status.exitstatus.should == 99
-    end
+  it "returns the pid and status of child process" do
+    pidf = Process.spawn(*ruby_exe, "-e", "exit 99")
+    results = Process.wait2
+    results.size.should == 2
+    pidw, status = results
+    pidf.should == pidw
+    status.exitstatus.should == 99
   end
 
   it "raises a StandardError if no child processes exist" do

core/process/wait_spec.rb

@@ -17,19 +17,19 @@
     -> { Process.wait }.should.raise(Errno::ECHILD)
   end
 
-  platform_is_not :windows do
-    it "returns its child pid" do
-      pid = Process.spawn(ruby_cmd('exit'))
-      Process.wait.should == pid
-    end
+  it "returns its child pid" do
+    pid = Process.spawn(ruby_cmd('exit'))
+    Process.wait.should == pid
+  end
 
-    it "sets $? to a Process::Status" do
-      pid = Process.spawn(ruby_cmd('exit'))
-      Process.wait
-      $?.should.is_a?(Process::Status)
-      $?.pid.should == pid
-    end
+  it "sets $? to a Process::Status" do
+    pid = Process.spawn(ruby_cmd('exit'))
+    Process.wait
+    $?.should.is_a?(Process::Status)
+    $?.pid.should == pid
+  end
 
+  platform_is_not :windows do
     it "waits for any child process if no pid is given" do
       pid = Process.spawn(ruby_cmd('exit'))
       Process.wait.should == pid
@@ -59,8 +59,10 @@
       Process.wait(0).should == pid2
       Process.wait.should == pid1
     end
+  end
 
-    # This spec is probably system-dependent.
+  # This spec is probably system-dependent.
+  guard -> { Process.respond_to?(:fork) } do
     it "doesn't block if no child is available when WNOHANG is used" do
       read, write = IO.pipe
       pid = Process.fork do
@@ -81,7 +83,9 @@
       Process.kill("TERM", pid)
       Process.wait.should == pid
     end
+  end
 
+  platform_is_not :windows do
     it "always accepts flags=0" do
       pid = Process.spawn(ruby_cmd('exit'))
       Process.wait(-1, 0).should == pid

core/process/waitall_spec.rb

@@ -1,6 +1,9 @@
 require_relative '../../spec_helper'
+require_relative 'fixtures/common'
 
 describe "Process.waitall" do
+  ProcessSpecs.use_system_ruby(self)
+
   before :all do
     begin
       Process.waitall
@@ -17,23 +20,16 @@
   end
 
   platform_is_not :windows do
-    it "waits for all children" do
+    it "waits for all children and returns an array of pid/status pairs" do
       pids = []
-      pids << Process.fork { Process.exit! 2 }
-      pids << Process.fork { Process.exit! 1 }
-      pids << Process.fork { Process.exit! 0 }
-      Process.waitall
+      pids << Process.spawn(ruby_cmd('exit 2'))
+      pids << Process.spawn(ruby_cmd('exit 1'))
+      pids << Process.spawn(ruby_cmd('exit 0'))
+      a = Process.waitall
       pids.each { |pid|
         -> { Process.kill(0, pid) }.should.raise(Errno::ESRCH)
       }
-    end
 
-    it "returns an array of pid/status pairs" do
-      pids = []
-      pids << Process.fork { Process.exit! 2 }
-      pids << Process.fork { Process.exit! 1 }
-      pids << Process.fork { Process.exit! 0 }
-      a = Process.waitall
       a.should.is_a?(Array)
       a.size.should == 3
       pids.each { |pid|