add tests

test/config/suppress_exception.rb

@@ -0,0 +1 @@
+raise_exception_on_sigterm false

test/test_config.rb

@@ -185,6 +185,17 @@ class TestConfigFile < Minitest::Test
     assert_equal 150, conf.options[:worker_shutdown_timeout]
   end
 
+  def test_config_raise_exception_on_sigterm
+    conf = Puma::Configuration.new do |c|
+      c.raise_exception_on_sigterm false
+    end
+    conf.load
+
+    assert_equal conf.options[:raise_exception_on_sigterm], false
+    conf.options[:raise_exception_on_sigterm] = true
+    assert_equal conf.options[:raise_exception_on_sigterm], true
+  end
+
   def teardown
     FileUtils.rm_r("config/puma")
   end

test/test_integration.rb

@@ -264,6 +264,31 @@ class TestIntegration < Minitest::Test
     assert_equal 15, status
   end
 
+  def test_term_signal_suppress_in_single_mode
+    skip NO_FORK_MSG unless HAS_FORK
+
+    pid = start_forked_server("-C test/config/suppress_exception.rb test/rackup/hello.ru")
+    _, status = stop_forked_server(pid)
+
+    assert_equal 0, status
+  end
+
+  def test_term_signal_suppress_in_clustered_mode
+    skip NO_FORK_MSG unless HAS_FORK
+
+    server("-w 2 -C test/config/suppress_exception.rb test/rackup/hello.ru")
+
+    Process.kill(:TERM, @server.pid)
+    begin
+      Process.wait @server.pid
+    rescue Errno::ECHILD
+    end
+    status = $?.exitstatus
+
+    assert_equal 0, status
+    @server = nil # prevent `#teardown` from killing already killed server
+  end
+
   def test_not_accepts_new_connections_after_term_signal
     skip_on :jruby, :windows