add spec Warning[category] = true|false to emit/suppress warnings

core/warning/element_reference_spec.rb

@@ -0,0 +1,14 @@
+require_relative '../../spec_helper'
+
+ruby_version_is '2.7' do
+  describe "Warning.[]" do
+    it "returns default values for categories :deprecated and :experimental" do
+      Warning[:deprecated].should == true
+      Warning[:experimental].should == true
+    end
+
+    it "raises for unknown category" do
+      -> { Warning[:noop] }.should raise_error(ArgumentError, /unknown category: noop/)
+    end
+  end
+end

core/warning/element_set_spec.rb

@@ -0,0 +1,27 @@
+require_relative '../../spec_helper'
+
+ruby_version_is '2.7' do
+  describe "Warning.[]=" do
+    it "sets new values for categories :deprecated and :experimental" do
+      Warning[:deprecated] = false
+      Warning[:deprecated].should == false
+
+      Warning[:experimental] = false
+      Warning[:experimental].should == false
+    end
+
+    it "raises for unknown category" do
+      -> { Warning[:noop] = false }.should raise_error(ArgumentError, /unknown category: noop/)
+    end
+
+    it "emits and suppresses warnings for :deprecated" do
+      ruby_exe('Warning[:deprecated] = true; $; = ""', args: "2>&1").should =~ /is deprecated/
+      ruby_exe('Warning[:deprecated] = false; $; = ""', args: "2>&1").should == ""
+    end
+
+    it "emits and suppresses warnings for :experimental" do
+      ruby_exe('Warning[:experimental] = true; eval("0 in a")', args: "2>&1").should =~ /is experimental/
+      ruby_exe('Warning[:experimental] = false; eval("0 in a")', args: "2>&1").should == ""
+    end
+  end
+end