Add missing test CopyUtils#testCopy_readerToOutputStreamString()

Author: Gary Gregory

src/test/java/org/apache/commons/io/CopyUtilsTest.java

@@ -224,6 +224,28 @@ public void testCopy_readerToOutputStream() throws Exception {
         assertArrayEquals(inData, baout.toByteArray(), "Content differs");
     }
 
+    @SuppressWarnings("resource") // 'in' is deliberately not closed
+    @Test
+    public void testCopy_readerToOutputStreamString() throws Exception {
+        InputStream in = new ByteArrayInputStream(inData);
+        in = new ThrowOnCloseInputStream(in);
+        final Reader reader = new java.io.InputStreamReader(in, StandardCharsets.US_ASCII);
+
+        final ByteArrayOutputStream baout = new ByteArrayOutputStream();
+        final OutputStream out = new ThrowOnFlushAndCloseOutputStream(baout, false, true);
+
+        CopyUtils.copy(reader, out, StandardCharsets.US_ASCII.name());
+        //Note: this method *does* flush. It is equivalent to:
+        //  OutputStreamWriter _out = new OutputStreamWriter(fout);
+        //  IOUtils.copy( fin, _out, 4096 ); // copy( Reader, Writer, int );
+        //  _out.flush();
+        //  out = fout;
+
+        // Note: rely on the method to flush
+        assertEquals(inData.length, baout.size(), "Sizes differ");
+        assertArrayEquals(inData, baout.toByteArray(), "Content differs");
+    }
+
     @Test
     public void testCtor() {
         new CopyUtils();