4 files changed, 128 insertions, 40 deletions
diff --git a/spec/ruby/core/warning/element_reference_spec.rb b/spec/ruby/core/warning/element_reference_spec.rb
index 67728ca0f6..c0ed37ef13 100644
--- a/spec/ruby/core/warning/element_reference_spec.rb
+++ b/spec/ruby/core/warning/element_reference_spec.rb
@@ -1,10 +1,19 @@
 require_relative '../../spec_helper'
 
 describe "Warning.[]" do
-  ruby_version_is '2.7.2' do
-    it "returns default values for categories :deprecated and :experimental" do
-      ruby_exe('p Warning[:deprecated]').chomp.should == "false"
-      ruby_exe('p Warning[:experimental]').chomp.should == "true"
+  it "returns default values for categories :deprecated and :experimental" do
+    # If any warning options were set on the Ruby that will be executed, then
+    # it's possible this test will fail. In this case we will skip this test.
+    skip if ruby_exe.any? { |opt| opt.start_with?("-W") }
+
+    ruby_exe('p [Warning[:deprecated], Warning[:experimental]]').chomp.should == "[false, true]"
+    ruby_exe('p [Warning[:deprecated], Warning[:experimental]]', options: "-w").chomp.should == "[true, true]"
+  end
+
+  ruby_version_is '3.3' do
+    it "returns default values for :performance category" do
+      ruby_exe('p Warning[:performance]').chomp.should == "false"
+      ruby_exe('p Warning[:performance]', options: "-w").chomp.should == "false"
     end
   end
 
diff --git a/spec/ruby/core/warning/element_set_spec.rb b/spec/ruby/core/warning/element_set_spec.rb
index d20ee215ad..d59a7d4c9e 100644
--- a/spec/ruby/core/warning/element_set_spec.rb
+++ b/spec/ruby/core/warning/element_set_spec.rb
@@ -8,13 +8,7 @@ describe "Warning.[]=" do
 
   describe ":experimental" do
     before do
-      ruby_version_is ""..."3.0" do
-        @src = 'case [0, 1]; in [a, b]; end'
-      end
-
-      ruby_version_is "3.0" do
-        @src = 'warn "This is experimental warning.", category: :experimental'
-      end
+      @src = 'warn "This is experimental warning.", category: :experimental'
     end
 
     it "emits and suppresses warnings for :experimental" do
@@ -23,6 +17,18 @@ describe "Warning.[]=" do
     end
   end
 
+  ruby_version_is '3.3' do
+    it "enables or disables performance warnings" do
+      original = Warning[:performance]
+      begin
+        Warning[:performance] = !original
+        Warning[:performance].should == !original
+      ensure
+        Warning[:performance] = original
+      end
+    end
+  end
+
   it "raises for unknown category" do
     -> { Warning[:noop] = false }.should raise_error(ArgumentError, /unknown category: noop/)
   end
diff --git a/spec/ruby/core/warning/performance_warning_spec.rb b/spec/ruby/core/warning/performance_warning_spec.rb
new file mode 100644
index 0000000000..ab0badcd3d
--- /dev/null
+++ b/spec/ruby/core/warning/performance_warning_spec.rb
@@ -0,0 +1,28 @@
+require_relative '../../spec_helper'
+
+
+describe "Performance warnings" do
+  guard -> { ruby_version_is("3.4") || RUBY_ENGINE == "truffleruby" } do
+    # Optimising Integer, Float or Symbol methods is kind of implementation detail
+    # but multiple implementations do so. So it seems reasonable to have a test case
+    # for at least one such common method.
+    # See https://bugs.ruby-lang.org/issues/20429
+    context "when redefined optimised methods" do
+      it "emits performance warning for redefining Integer#+" do
+        code = <<~CODE
+          Warning[:performance] = true
+
+          class Integer
+            ORIG_METHOD = instance_method(:+)
+
+            def +(...)
+              ORIG_METHOD.bind(self).call(...)
+            end
+          end
+        CODE
+
+        ruby_exe(code, args: "2>&1").should.include?("warning: Redefining 'Integer#+' disables interpreter and JIT optimizations")
+      end
+    end
+  end
+end
diff --git a/spec/ruby/core/warning/warn_spec.rb b/spec/ruby/core/warning/warn_spec.rb
index 5ccff3aa2b..8f96fe9287 100644
--- a/spec/ruby/core/warning/warn_spec.rb
+++ b/spec/ruby/core/warning/warn_spec.rb
@@ -51,40 +51,85 @@ describe "Warning.warn" do
     end
   end
 
-  ruby_version_is '3.0' do
-    it "is called by Kernel.warn with nil category keyword" do
-      Warning.should_receive(:warn).with("Chunky bacon!\n", category: nil)
-      verbose = $VERBOSE
-      $VERBOSE = false
-      begin
-        Kernel.warn("Chunky bacon!")
-      ensure
-        $VERBOSE = verbose
-      end
+  it "is called by Kernel.warn with nil category keyword" do
+    Warning.should_receive(:warn).with("Chunky bacon!\n", category: nil)
+    verbose = $VERBOSE
+    $VERBOSE = false
+    begin
+      Kernel.warn("Chunky bacon!")
+    ensure
+      $VERBOSE = verbose
     end
+  end
 
-    it "is called by Kernel.warn with given category keyword converted to a symbol" do
-      Warning.should_receive(:warn).with("Chunky bacon!\n", category: :deprecated)
-      verbose = $VERBOSE
-      $VERBOSE = false
-      begin
-        Kernel.warn("Chunky bacon!", category: "deprecated")
-      ensure
-        $VERBOSE = verbose
-      end
+  it "is called by Kernel.warn with given category keyword converted to a symbol" do
+    Warning.should_receive(:warn).with("Chunky bacon!\n", category: :deprecated)
+    verbose = $VERBOSE
+    $VERBOSE = false
+    begin
+      Kernel.warn("Chunky bacon!", category: "deprecated")
+    ensure
+      $VERBOSE = verbose
     end
   end
 
-  ruby_version_is ''...'3.0' do
-    it "is called by Kernel.warn" do
-      Warning.should_receive(:warn).with("Chunky bacon!\n")
-      verbose = $VERBOSE
-      $VERBOSE = false
-      begin
-        Kernel.warn("Chunky bacon!")
-      ensure
-        $VERBOSE = verbose
-      end
+  it "warns when category is :deprecated and Warning[:deprecated] is true" do
+    warn_deprecated = Warning[:deprecated]
+    Warning[:deprecated] = true
+    begin
+      -> {
+        Warning.warn("foo", category: :deprecated)
+      }.should complain("foo")
+    ensure
+      Warning[:deprecated] = warn_deprecated
     end
   end
+
+  it "warns when category is :experimental and Warning[:experimental] is true" do
+    warn_experimental = Warning[:experimental]
+    Warning[:experimental] = true
+    begin
+      -> {
+        Warning.warn("foo", category: :experimental)
+      }.should complain("foo")
+    ensure
+      Warning[:experimental] = warn_experimental
+    end
+  end
+
+  it "doesn't print message when category is :deprecated but Warning[:deprecated] is false" do
+    warn_deprecated = Warning[:deprecated]
+    Warning[:deprecated] = false
+    begin
+      -> {
+        Warning.warn("foo", category: :deprecated)
+      }.should_not complain
+    ensure
+      Warning[:deprecated] = warn_deprecated
+    end
+  end
+
+  it "doesn't print message when category is :experimental but Warning[:experimental] is false" do
+    warn_experimental = Warning[:experimental]
+    Warning[:experimental] = false
+    begin
+      -> {
+        Warning.warn("foo", category: :experimental)
+      }.should_not complain
+    ensure
+      Warning[:experimental] = warn_experimental
+    end
+  end
+
+  it "prints the message when VERBOSE is false" do
+    -> { Warning.warn("foo") }.should complain("foo")
+  end
+
+  it "prints the message when VERBOSE is nil" do
+    -> { Warning.warn("foo") }.should complain("foo", verbose: nil)
+  end
+
+  it "prints the message when VERBOSE is true" do
+    -> { Warning.warn("foo") }.should complain("foo", verbose: true)
+  end
 end