1 files changed, 63 insertions, 19 deletions
diff --git a/spec/ruby/library/stringio/shared/write.rb b/spec/ruby/library/stringio/shared/write.rb
index 080729217b..b6bffe7f12 100644
--- a/spec/ruby/library/stringio/shared/write.rb
+++ b/spec/ruby/library/stringio/shared/write.rb
@@ -1,6 +1,6 @@
 describe :stringio_write, shared: true do
   before :each do
-    @io = StringIO.new('12345')
+    @io = StringIO.new(+'12345')
   end
 
   it "tries to convert the passed Object to a String using #to_s" do
@@ -13,7 +13,7 @@ end
 
 describe :stringio_write_string, shared: true do
   before :each do
-    @io = StringIO.new('12345')
+    @io = StringIO.new(+'12345')
   end
 
   # TODO: RDoc says that #write appends at the current position.
@@ -42,38 +42,82 @@ describe :stringio_write_string, shared: true do
 
   it "updates self's position" do
     @io.send(@method, 'test')
-    @io.pos.should eql(4)
+    @io.pos.should.eql?(4)
   end
 
-  ruby_version_is ""..."2.7" do
-    it "taints self's String when the passed argument is tainted" do
-      @io.send(@method, "test".taint)
-      @io.string.tainted?.should be_true
-    end
+  it "handles concurrent writes correctly" do
+    @io = StringIO.new
+    n = 8
+    go = false
+    threads = n.times.map { |i|
+      Thread.new {
+        Thread.pass until go
+        @io.write i.to_s
+      }
+    }
+    go = true
+    threads.each(&:join)
+    @io.string.size.should == n.times.map(&:to_s).join.size
   end
 
-  ruby_version_is ""..."3.0" do
-    it "does not taint self when the passed argument is tainted" do
-      @io.send(@method, "test".taint)
-      @io.tainted?.should be_false
-    end
+  it "handles writing non-ASCII UTF-8 after seek" do
+    @io.binmode
+    @io << "\x80"
+    @io.pos = 0
+    @io << "\x81"
+    @io.string.should == "\x812345".b
+  end
+
+  it "handles writing with position < buffer size" do
+    @io.pos = 2
+    @io.write "abc"
+    @io.string.should == "12abc"
+
+    @io.pos = 2
+    @io.write "de"
+    @io.string.should == "12dec"
+
+    @io.pos = 2
+    @io.write "fghi"
+    @io.string.should == "12fghi"
+  end
+
+  it "transcodes the given string when the external encoding is set and neither is BINARY" do
+    utf8_str = "hello"
+    io = StringIO.new.set_encoding(Encoding::UTF_16BE)
+    io.external_encoding.should == Encoding::UTF_16BE
+
+    io.send(@method, utf8_str)
+
+    expected = [0, 104, 0, 101, 0, 108, 0, 108, 0, 111] # UTF-16BE bytes for "hello"
+    io.string.bytes.should == expected
+  end
+
+  it "does not transcode the given string when the external encoding is set and the string encoding is BINARY" do
+    str = "été_".b
+    io = StringIO.new.set_encoding(Encoding::UTF_16BE)
+    io.external_encoding.should == Encoding::UTF_16BE
+
+    io.send(@method, str)
+
+    io.string.bytes.should == str.bytes
   end
 end
 
 describe :stringio_write_not_writable, shared: true do
   it "raises an IOError" do
-    io = StringIO.new("test", "r")
-    -> { io.send(@method, "test") }.should raise_error(IOError)
+    io = StringIO.new(+"test", "r")
+    -> { io.send(@method, "test") }.should.raise(IOError)
 
-    io = StringIO.new("test")
+    io = StringIO.new(+"test")
     io.close_write
-    -> { io.send(@method, "test") }.should raise_error(IOError)
+    -> { io.send(@method, "test") }.should.raise(IOError)
   end
 end
 
 describe :stringio_write_append, shared: true do
   before :each do
-    @io = StringIO.new("example", "a")
+    @io = StringIO.new(+"example", "a")
   end
 
   it "appends the passed argument to the end of self" do
@@ -86,6 +130,6 @@ describe :stringio_write_append, shared: true do
 
   it "correctly updates self's position" do
     @io.send(@method, ", testing")
-    @io.pos.should eql(16)
+    @io.pos.should.eql?(16)
   end
 end