[IO-887] WriterOutputStream fails on malformed input by default for

Cp850 input bytes.

Author: garydgregory

src/changes/changes.xml

@@ -61,6 +61,7 @@ The <action> type attribute can be add,update,fix,remove.
       <action type="fix" dev="ggregory" due-to="Kishor, Mashrur Mia" issue="IO-639">ReversedLinesFileReader does not read first line if its empty #829.</action>
       <action type="fix" dev="ggregory" due-to="Peter De Maeyer" issue="IO-886">Fixed incorrect regular expression in PathUtils.RelativeSortedPaths.extractKey(String, String).</action>
       <action type="fix" dev="ggregory" due-to="Martin Wiesner">Fix typos in Javadoc of FileUtils and related test classes #833.</action>
+      <action type="fix" dev="ggregory" due-to="Daniel Vega, Gary Gregory" issue="IO-887">WriterOutputStream fails on malformed input by default for Cp850 input bytes.</action>
       <!-- ADD -->
       <action type="add" dev="ggregory" due-to="Gary Gregory, Piotr P. Karwasz">Add and use IOUtils.closeQuietlySuppress(Closeable, Throwable) #818.</action>
       <action type="add" dev="ggregory" due-to="Gary Gregory">Add ProxyWriter.setReference(Writer).</action>

src/main/java/org/apache/commons/io/output/WriterOutputStream.java

@@ -143,14 +143,14 @@ public WriterOutputStream get() throws IOException {
         @Override
         public Builder setCharset(final Charset charset) {
             super.setCharset(charset);
-            this.charsetDecoder = getCharset().newDecoder();
+            this.charsetDecoder = newDecoder(getCharset());
             return this;
         }
 
         @Override
         public Builder setCharset(final String charset) {
             super.setCharset(charset);
-            this.charsetDecoder = getCharset().newDecoder();
+            this.charsetDecoder = newDecoder(getCharset());
             return this;
         }
 
@@ -204,12 +204,12 @@ private static void checkIbmJdkWithBrokenUTF16(final Charset charset) {
         if (!StandardCharsets.UTF_16.name().equals(charset.name())) {
             return;
         }
-        final String TEST_STRING_2 = "v\u00e9s";
-        final byte[] bytes = TEST_STRING_2.getBytes(charset);
+        final String testString = "v\u00e9s";
+        final byte[] bytes = testString.getBytes(charset);
 
         final CharsetDecoder charsetDecoder2 = charset.newDecoder();
         final ByteBuffer bb2 = ByteBuffer.allocate(16);
-        final CharBuffer cb2 = CharBuffer.allocate(TEST_STRING_2.length());
+        final CharBuffer cb2 = CharBuffer.allocate(testString.length());
         final int len = bytes.length;
         for (int i = 0; i < len; i++) {
             bb2.put(bytes[i]);
@@ -223,14 +223,24 @@ private static void checkIbmJdkWithBrokenUTF16(final Charset charset) {
             bb2.compact();
         }
         cb2.rewind();
-        if (!TEST_STRING_2.equals(cb2.toString())) {
+        if (!testString.equals(cb2.toString())) {
             throw new UnsupportedOperationException("UTF-16 requested when running on an IBM JDK with broken UTF-16 support. "
                     + "Please find a JDK that supports UTF-16 if you intend to use UF-16 with WriterOutputStream");
         }
 
     }
 
+    private static CharsetDecoder newDecoder(final Charset charset) {
+        // @formatter:off
+        return Charsets.toCharset(charset).newDecoder()
+            .onMalformedInput(CodingErrorAction.REPLACE)
+            .onUnmappableCharacter(CodingErrorAction.REPLACE)
+            .replaceWith("?");
+        // @formatter:on
+    }
+
     private final Writer writer;
+
     private final CharsetDecoder decoder;
 
     private final boolean writeImmediately;
@@ -289,15 +299,7 @@ public WriterOutputStream(final Writer writer, final Charset charset) {
      */
     @Deprecated
     public WriterOutputStream(final Writer writer, final Charset charset, final int bufferSize, final boolean writeImmediately) {
-        // @formatter:off
-        this(writer,
-            Charsets.toCharset(charset).newDecoder()
-                    .onMalformedInput(CodingErrorAction.REPLACE)
-                    .onUnmappableCharacter(CodingErrorAction.REPLACE)
-                    .replaceWith("?"),
-             bufferSize,
-             writeImmediately);
-        // @formatter:on
+        this(writer, newDecoder(charset), bufferSize, writeImmediately);
     }
 
     /**

src/test/java/org/apache/commons/io/output/WriterOutputStreamTest.java

@@ -58,6 +58,22 @@ void testFlush() throws IOException {
         }
     }
 
+    @Test
+    void testIO887() throws IOException {
+        final StringWriter stringWriter1 = new StringWriter();
+        final Charset charset = StandardCharsets.UTF_8;
+        try (WriterOutputStream writerOutputStream = new WriterOutputStream(stringWriter1, charset)) {
+            writerOutputStream.write("¿Cómo estás".getBytes("Cp850"));
+        }
+        final String expected = "?C?mo est?s";
+        assertEquals(expected, stringWriter1.toString());
+        final StringWriter stringWriter2 = new StringWriter();
+        try (WriterOutputStream writerOutputStream = WriterOutputStream.builder().setWriter(stringWriter2).setCharset(charset).get()) {
+            writerOutputStream.write("¿Cómo estás".getBytes("Cp850"));
+        }
+        assertEquals(expected, stringWriter2.toString());
+    }
+
     @Test
     void testLargeUTF8CharsetWithBufferedWrite() throws IOException {
         testWithBufferedWrite(LARGE_TEST_STRING, UTF_8);