4 files changed, 24 insertions, 0 deletions
diff --git a/spec/rubyspec/core/string/capitalize_spec.rb b/spec/rubyspec/core/string/capitalize_spec.rb
index b70509da99..e2d2b68caa 100644
--- a/spec/rubyspec/core/string/capitalize_spec.rb
+++ b/spec/rubyspec/core/string/capitalize_spec.rb
@@ -25,6 +25,12 @@ describe "String#capitalize" do
     end
   end
 
+  ruby_version_is '2.4' do
+    it "works for all of Unicode" do
+      "äöü".capitalize.should == "Äöü"
+    end
+  end
+
   it "returns subclass instances when called on a subclass" do
     StringSpecs::MyString.new("hello").capitalize.should be_an_instance_of(StringSpecs::MyString)
     StringSpecs::MyString.new("Hello").capitalize.should be_an_instance_of(StringSpecs::MyString)
diff --git a/spec/rubyspec/core/string/downcase_spec.rb b/spec/rubyspec/core/string/downcase_spec.rb
index d31b6633df..9ebc4f2bd1 100644
--- a/spec/rubyspec/core/string/downcase_spec.rb
+++ b/spec/rubyspec/core/string/downcase_spec.rb
@@ -22,6 +22,12 @@ describe "String#downcase" do
     end
   end
 
+  ruby_version_is '2.4' do
+    it "works for all of Unicode" do
+      "ÄÖÜ".downcase.should == "äöü"
+    end
+  end
+
   it "taints result when self is tainted" do
     "".taint.downcase.tainted?.should == true
     "x".taint.downcase.tainted?.should == true
diff --git a/spec/rubyspec/core/string/swapcase_spec.rb b/spec/rubyspec/core/string/swapcase_spec.rb
index 0085887ae2..e9af647727 100644
--- a/spec/rubyspec/core/string/swapcase_spec.rb
+++ b/spec/rubyspec/core/string/swapcase_spec.rb
@@ -22,6 +22,12 @@ describe "String#swapcase" do
     end
   end
 
+  ruby_version_is '2.4' do
+    it "works for all of Unicode" do
+      "äÖü".swapcase.should == "ÄöÜ"
+    end
+  end
+
   it "returns subclass instances when called on a subclass" do
     StringSpecs::MyString.new("").swapcase.should be_an_instance_of(StringSpecs::MyString)
     StringSpecs::MyString.new("hello").swapcase.should be_an_instance_of(StringSpecs::MyString)
diff --git a/spec/rubyspec/core/string/upcase_spec.rb b/spec/rubyspec/core/string/upcase_spec.rb
index e23a9829d9..2fdcce86b9 100644
--- a/spec/rubyspec/core/string/upcase_spec.rb
+++ b/spec/rubyspec/core/string/upcase_spec.rb
@@ -22,6 +22,12 @@ describe "String#upcase" do
     end
   end
 
+  ruby_version_is '2.4' do
+    it "works for all of Unicode" do
+      "äöü".upcase.should == "ÄÖÜ"
+    end
+  end
+
   it "taints result when self is tainted" do
     "".taint.upcase.tainted?.should == true
     "X".taint.upcase.tainted?.should == true