1 files changed, 81 insertions, 0 deletions
diff --git a/test/ruby/test_stack.rb b/test/ruby/test_stack.rb
new file mode 100644
index 0000000000..6657b9e83c
--- /dev/null
+++ b/test/ruby/test_stack.rb
@@ -0,0 +1,81 @@
+# frozen_string_literal: false
+require 'test/unit'
+require 'tmpdir'
+
+class TestStack < Test::Unit::TestCase
+  LARGE_VM_STACK_SIZE = 1024*1024*5
+  LARGE_MACHINE_STACK_SIZE = 1024*1024*10
+
+  def initialize(*)
+    super
+
+    @h_default = nil
+    @h_0 = nil
+    @h_large = nil
+  end
+
+  def invoke_ruby script, vm_stack_size: nil, machine_stack_size: nil
+    env = {}
+    env['RUBY_FIBER_VM_STACK_SIZE'] = vm_stack_size.to_s if vm_stack_size
+    env['RUBY_FIBER_MACHINE_STACK_SIZE'] = machine_stack_size.to_s if machine_stack_size
+
+    stdout, stderr, status = EnvUtil.invoke_ruby([env, '-e', script], '', true, true, timeout: 30)
+    assert(!status.signaled?, FailDesc[status, nil, stderr])
+
+    return stdout
+  end
+
+  def h_default
+    @h_default ||= eval(invoke_ruby('p RubyVM::DEFAULT_PARAMS'))
+  end
+
+  def h_0
+    @h_0 ||= eval(invoke_ruby('p RubyVM::DEFAULT_PARAMS',
+      vm_stack_size: 0,
+      machine_stack_size: 0
+    ))
+  end
+
+  def h_large
+    @h_large ||= eval(invoke_ruby('p RubyVM::DEFAULT_PARAMS',
+      vm_stack_size: LARGE_VM_STACK_SIZE,
+      machine_stack_size: LARGE_MACHINE_STACK_SIZE
+    ))
+  end
+
+  def test_relative_stack_sizes
+    assert_operator(h_default[:fiber_vm_stack_size], :>, h_0[:fiber_vm_stack_size])
+    assert_operator(h_default[:fiber_vm_stack_size], :<, h_large[:fiber_vm_stack_size])
+    assert_operator(h_default[:fiber_machine_stack_size], :>=, h_0[:fiber_machine_stack_size])
+    assert_operator(h_default[:fiber_machine_stack_size], :<=, h_large[:fiber_machine_stack_size])
+  end
+
+  def test_vm_stack_size
+    script = '$stdout.sync=true; def rec; print "."; rec; end; Fiber.new{rec}.resume'
+    
+    size_default = invoke_ruby(script).bytesize
+    assert_operator(size_default, :>, 0)
+    
+    size_0 = invoke_ruby(script, vm_stack_size: 0).bytesize
+    assert_operator(size_default, :>, size_0)
+    
+    size_large = invoke_ruby(script, vm_stack_size: LARGE_VM_STACK_SIZE).bytesize
+    assert_operator(size_default, :<, size_large)
+  end
+
+  # Depending on OS, machine stack size may not change size.
+  def test_machine_stack_size
+    return if /mswin|mingw/ =~ RUBY_PLATFORM
+
+    script = '$stdout.sync=true; def rec; print "."; 1.times{1.times{1.times{rec}}}; end; Fiber.new{rec}.resume'
+
+    vm_stack_size = 1024 * 1024
+    size_default = invoke_ruby(script, vm_stack_size: vm_stack_size).bytesize
+
+    size_0 = invoke_ruby(script, vm_stack_size: vm_stack_size, machine_stack_size: 0).bytesize
+    assert_operator(size_default, :>=, size_0)
+
+    size_large = invoke_ruby(script, vm_stack_size: vm_stack_size, machine_stack_size: LARGE_MACHINE_STACK_SIZE).bytesize
+    assert_operator(size_default, :<=, size_large)
+  end
+end