1 files changed, 181 insertions, 65 deletions
diff --git a/spec/ruby/core/objectspace/define_finalizer_spec.rb b/spec/ruby/core/objectspace/define_finalizer_spec.rb
index 969e8b16b0..5441cb4a21 100644
--- a/spec/ruby/core/objectspace/define_finalizer_spec.rb
+++ b/spec/ruby/core/objectspace/define_finalizer_spec.rb
@@ -1,101 +1,217 @@
-require File.expand_path('../../../spec_helper', __FILE__)
-require File.expand_path('../fixtures/classes', __FILE__)
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+
+# Why do we not test that finalizers are run by the GC? The documentation
+# says that finalizers are never guaranteed to be run, so we can't
+# spec that they are. On some implementations of Ruby the finalizers may
+# run asynchronously, meaning that we can't predict when they'll run,
+# even if they were guaranteed to do so. Even on MRI finalizers can be
+# very unpredictable, due to conservative stack scanning and references
+# left in unused memory.
 
-# NOTE: A call to define_finalizer does not guarantee that the
-# passed proc or callable will be called at any particular time.
-# It is highly questionable whether these aspects of ObjectSpace
-# should be spec'd at all.
 describe "ObjectSpace.define_finalizer" do
   it "raises an ArgumentError if the action does not respond to call" do
-    lambda {
-      ObjectSpace.define_finalizer("", mock("ObjectSpace.define_finalizer no #call"))
-    }.should raise_error(ArgumentError)
+    -> {
+      ObjectSpace.define_finalizer(Object.new, mock("ObjectSpace.define_finalizer no #call"))
+    }.should.raise(ArgumentError)
   end
 
   it "accepts an object and a proc" do
-    handler = lambda { |obj| obj }
-    ObjectSpace.define_finalizer("garbage", handler).should == [0, handler]
+    handler = -> id { id }
+    ObjectSpace.define_finalizer(Object.new, handler).should == [0, handler]
+  end
+
+  it "accepts an object and a bound method" do
+    handler = mock("callable")
+    def handler.finalize(id) end
+    finalize = handler.method(:finalize)
+    ObjectSpace.define_finalizer(Object.new, finalize).should == [0, finalize]
   end
 
   it "accepts an object and a callable" do
     handler = mock("callable")
-    def handler.call(obj) end
-    ObjectSpace.define_finalizer("garbage", handler).should == [0, handler]
+    def handler.call(id) end
+    ObjectSpace.define_finalizer(Object.new, handler).should == [0, handler]
+  end
+
+  it "accepts an object and a block" do
+    handler = -> id { id }
+    ObjectSpace.define_finalizer(Object.new, &handler).should == [0, handler]
   end
 
   it "raises ArgumentError trying to define a finalizer on a non-reference" do
-    lambda {
+    -> {
       ObjectSpace.define_finalizer(:blah) { 1 }
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
   end
 
   # see [ruby-core:24095]
-  with_feature :fork do
-    it "calls finalizer on process termination" do
-      rd, wr = IO.pipe
-      pid = Process.fork do
-        rd.close
-        handler = ObjectSpaceFixtures.scoped(wr)
-        obj = "Test"
-        ObjectSpace.define_finalizer(obj, handler)
-        exit 0
+  it "calls finalizer on process termination" do
+    code = <<-RUBY
+      def scoped
+        Proc.new { puts "finalizer run" }
       end
+      handler = scoped
+      obj = +"Test"
+      ObjectSpace.define_finalizer(obj, handler)
+      exit 0
+    RUBY
 
-      wr.close
-      begin
-        rd.read.should == "finalized"
-      ensure
-        rd.close
-        Process.wait pid
+    ruby_exe(code, :args => "2>&1").should.include?("finalizer run\n")
+  end
+
+  it "warns if the finalizer has the object as the receiver" do
+    code = <<-RUBY
+      class CapturesSelf
+        def initialize
+          ObjectSpace.define_finalizer(self, proc {
+            puts "finalizer run"
+          })
+        end
       end
-    end
+      CapturesSelf.new
+      exit 0
+    RUBY
 
-    it "calls finalizer at exit even if it is self-referencing" do
-      rd, wr = IO.pipe
-      pid = Process.fork do
-        rd.close
-        obj = "Test"
-        handler = Proc.new { wr.write "finalized"; wr.close }
-        ObjectSpace.define_finalizer(obj, handler)
-        exit 0
+    ruby_exe(code, :args => "2>&1").should.include?("warning: finalizer references object to be finalized\n")
+  end
+
+  it "warns if the finalizer is a method bound to the receiver" do
+    code = <<-RUBY
+      class CapturesSelf
+        def initialize
+          ObjectSpace.define_finalizer(self, method(:finalize))
+        end
+        def finalize(id)
+          puts "finalizer run"
+        end
       end
+      CapturesSelf.new
+      exit 0
+    RUBY
+
+    ruby_exe(code, :args => "2>&1").should.include?("warning: finalizer references object to be finalized\n")
+  end
 
-      wr.close
-      begin
-        rd.read.should == "finalized"
-      ensure
-        rd.close
-        Process.wait pid
+  it "warns if the finalizer was a block in the receiver" do
+    code = <<-RUBY
+      class CapturesSelf
+        def initialize
+          ObjectSpace.define_finalizer(self) do
+            puts "finalizer run"
+          end
+        end
       end
-    end
+      CapturesSelf.new
+      exit 0
+    RUBY
 
-    # These specs are defined under the fork specs because there is no
-    # deterministic way to force finalizers to be run, except process exit, so
-    # we rely on that.
-    it "allows multiple finalizers with different 'callables' to be defined" do
-      rd1, wr1 = IO.pipe
-      rd2, wr2 = IO.pipe
+    ruby_exe(code, :args => "2>&1").should.include?("warning: finalizer references object to be finalized\n")
+  end
 
-      pid = Kernel::fork do
-        rd1.close
-        rd2.close
-        obj = mock("ObjectSpace.define_finalizer multiple")
+  it "calls a finalizer at exit even if it is self-referencing" do
+    code = <<-RUBY
+      obj = +"Test"
+      handler = Proc.new { puts "finalizer run" }
+      ObjectSpace.define_finalizer(obj, handler)
+      exit 0
+    RUBY
 
-        ObjectSpace.define_finalizer(obj, Proc.new { wr1.write "finalized1"; wr1.close })
-        ObjectSpace.define_finalizer(obj, Proc.new { wr2.write "finalized2"; wr2.close })
+    ruby_exe(code).should.include?("finalizer run\n")
+  end
+
+  it "calls a finalizer at exit even if it is indirectly self-referencing" do
+    code = <<-RUBY
+      class CapturesSelf
+        def initialize
+          ObjectSpace.define_finalizer(self, finalizer(self))
+        end
+        def finalizer(zelf)
+          proc do
+            puts "finalizer run"
+          end
+        end
+      end
+      CapturesSelf.new
+      exit 0
+    RUBY
 
+    ruby_exe(code, :args => "2>&1").should.include?("finalizer run\n")
+  end
+
+  it "calls a finalizer defined in a finalizer running at exit" do
+    code = <<-RUBY
+      obj = +"Test"
+      handler = Proc.new do
+        obj2 = +"Test"
+        handler2 = Proc.new { puts "finalizer 2 run" }
+        ObjectSpace.define_finalizer(obj2, handler2)
         exit 0
       end
+      ObjectSpace.define_finalizer(obj, handler)
+      exit 0
+    RUBY
+
+    ruby_exe(code, :args => "2>&1").should.include?("finalizer 2 run\n")
+  end
+
+  it "allows multiple finalizers with different 'callables' to be defined" do
+    code = <<-'RUBY'
+      obj = Object.new
+
+      ObjectSpace.define_finalizer(obj, Proc.new { STDOUT.write "finalized1\n" })
+      ObjectSpace.define_finalizer(obj, Proc.new { STDOUT.write "finalized2\n" })
+
+      exit 0
+    RUBY
+
+    ruby_exe(code).lines.sort.should == ["finalized1\n", "finalized2\n"]
+  end
+
+  it "defines same finalizer only once" do
+    code = <<~RUBY
+      obj = Object.new
+      p = proc { |id| print "ok" }
+      ObjectSpace.define_finalizer(obj, p.dup)
+      ObjectSpace.define_finalizer(obj, p.dup)
+    RUBY
 
-      wr1.close
-      wr2.close
+    ruby_exe(code).should == "ok"
+  end
+
+  it "returns the defined finalizer" do
+    obj = Object.new
+    p = proc { |id| }
+    p2 = p.dup
+
+    ret = ObjectSpace.define_finalizer(obj, p)
+    ret.should == [0, p]
+    ret[1].should.equal?(p)
+
+    ret = ObjectSpace.define_finalizer(obj, p2)
+    ret.should == [0, p]
+    ret[1].should.equal?(p)
+  end
+
+  describe "when $VERBOSE is not nil" do
+    it "warns if an exception is raised in finalizer" do
+      code = <<-RUBY
+        ObjectSpace.define_finalizer(Object.new) { raise "finalizing" }
+      RUBY
+
+      out = ruby_exe(code, args: "2>&1")
+      out.should.include?("warning: Exception in finalizer")
+      out.should.include?("finalizing")
+    end
+  end
 
-      rd1.read.should == "finalized1"
-      rd2.read.should == "finalized2"
+  describe "when $VERBOSE is nil" do
+    it "does not warn even if an exception is raised in finalizer" do
+      code = <<-RUBY
+        ObjectSpace.define_finalizer(Object.new) { raise "finalizing" }
+      RUBY
 
-      rd1.close
-      rd2.close
-      Process.wait pid
+      ruby_exe(code, args: "2>&1", options: "-W0").should == ""
     end
   end
 end