Remove tests for byte oriented read when character buffer is nonempty

There is uncertainty regarding whether or not raising an IOError in such cases is intentional in CRuby.
I opened https://bugs.ruby-lang.org/issues/22230 to get confirmation either way, and this commit may be
reverted based on the outcome.

Author: javanthropus

core/io/getbyte_spec.rb

@@ -32,15 +32,6 @@
     @io.ungetc(c)
     @io.getbyte.should == 86
   end
-
-  it "raises an exception after ungetc with character conversion" do
-    @io.set_encoding("utf-8:utf-16be")
-    c = @io.getc
-    @io.ungetc(c)
-    -> do
-      @io.getbyte
-    end.should.raise(IOError, "byte oriented read for character buffered IO")
-  end
 end
 
 describe "IO#getbyte" do

core/io/read_nonblock_spec.rb

@@ -66,18 +66,6 @@
     @read.read_nonblock(3).should == "bar"
   end
 
-  it "raises an exception after ungetc with character conversion enabled" do
-    @write.write("foobar")
-    @read.set_encoding(
-      'utf-8', universal_newline: true
-    )
-    c = @read.getc
-    @read.ungetc(c)
-    -> do
-      @read.read_nonblock(3)
-    end.should.raise(IOError, "byte oriented read for character buffered IO")
-  end
-
   it "returns less data if that is all that is available" do
     @write << "hello"
     @read.read_nonblock(10).should == "hello"

core/io/read_spec.rb

@@ -686,14 +686,6 @@
         @io = IOSpecs.io_fixture "read_euc_jp.txt", "r:euc-jp:utf-8"
       end
 
-      it "raises an exception after ungetc" do
-        c = @io.getc
-        @io.ungetc(c)
-        -> do
-          @io.read(2)
-        end.should.raise(IOError, "byte oriented read for character buffered IO")
-      end
-
       it_behaves_like :io_read_internal_encoding, nil
       it_behaves_like :io_read_size_internal_encoding, nil
     end
@@ -703,14 +695,6 @@
         @io = IOSpecs.io_fixture "read_euc_jp.txt", mode: "r:euc-jp:utf-8"
       end
 
-      it "raises an exception after ungetc" do
-        c = @io.getc
-        @io.ungetc(c)
-        -> do
-          @io.read(2)
-        end.should.raise(IOError, "byte oriented read for character buffered IO")
-      end
-
       it_behaves_like :io_read_internal_encoding, nil
       it_behaves_like :io_read_size_internal_encoding, nil
     end
@@ -723,14 +707,6 @@
         @io = IOSpecs.io_fixture "read_euc_jp.txt", options
       end
 
-      it "raises an exception after ungetc" do
-        c = @io.getc
-        @io.ungetc(c)
-        -> do
-          @io.read(2)
-        end.should.raise(IOError, "byte oriented read for character buffered IO")
-      end
-
       it_behaves_like :io_read_internal_encoding, nil
       it_behaves_like :io_read_size_internal_encoding, nil
     end
@@ -741,14 +717,6 @@
         @io = IOSpecs.io_fixture "read_euc_jp.txt", options
       end
 
-      it "raises an exception after ungetc" do
-        c = @io.getc
-        @io.ungetc(c)
-        -> do
-          @io.read(2)
-        end.should.raise(IOError, "byte oriented read for character buffered IO")
-      end
-
       it_behaves_like :io_read_internal_encoding, nil
       it_behaves_like :io_read_size_internal_encoding, nil
     end

core/io/readbyte_spec.rb

@@ -28,13 +28,4 @@
     @io.ungetc(c)
     @io.readbyte.should == ?r.getbyte(0)
   end
-
-  it "raises an exception after ungetc with character conversion" do
-    @io.set_encoding("utf-8:utf-16be")
-    c = @io.getc
-    @io.ungetc(c)
-    -> do
-      @io.readbyte
-    end.should.raise(IOError, "byte oriented read for character buffered IO")
-  end
 end

core/io/readpartial_spec.rb

@@ -58,16 +58,6 @@
     @rd.readpartial(2).should == "b"
   end
 
-  it "raises an exception after ungetc with character conversion enabled" do
-    @wr.write("foobar")
-    @rd.set_encoding('utf-8', 'ascii')
-    c = @rd.getc
-    @rd.ungetc(c)
-    -> do
-      @rd.readpartial(3)
-    end.should.raise(IOError, "byte oriented read for character buffered IO")
-  end
-
   it "discards the existing buffer content upon successful read" do
     buffer = +"existing content"
     @wr.write("hello world")

core/io/sysread_spec.rb

@@ -57,14 +57,6 @@
     end.should.raise(IOError, "sysread for buffered IO")
   end
 
-  it "raises an error when called with a non-empty character buffer" do
-    @file.set_encoding(Encoding::UTF_8, Encoding::UTF_16BE)
-    @file.ungetc("a".encode(Encoding::UTF_16BE))
-    -> do
-      @file.sysread(5)
-    end.should.raise(IOError, "byte oriented read for character buffered IO")
-  end
-
   it "reads normally even when called immediately after a buffered IO#read" do
     @file.read(15)
     @file.sysread(5).should == "56789"

core/io/sysseek_spec.rb

@@ -33,14 +33,6 @@
     end.should.raise(IOError, "sysseek for buffered IO")
   end
 
-  it "raises an error when called with a non-empty character buffer" do
-    @io.set_encoding(Encoding::UTF_8, Encoding::UTF_16BE)
-    @io.ungetc("a".encode(Encoding::UTF_16BE))
-    -> do
-      @io.sysseek(-5, IO::SEEK_CUR)
-    end.should.raise(IOError, "sysseek for buffered IO")
-  end
-
   it "seeks normally even when called immediately after a buffered IO#read" do
     @io.read(15)
     @io.sysseek(-5, IO::SEEK_CUR).should == 10

core/io/ungetc_spec.rb

@@ -97,12 +97,6 @@
     @io.pos.should == pos - 1
   end
 
-  it "makes subsequent unbuffered operations to raise IOError" do
-    @io.getc
-    @io.ungetc(100)
-    -> { @io.sysread(1) }.should.raise(IOError)
-  end
-
   it "raises TypeError if passed nil" do
     @io.getc.should == ?V
     proc{@io.ungetc(nil)}.should raise_consistent_error(TypeError, /no implicit conversion of nil into String/)