ReaderInputStream.available() should return 0 after the stream is closed

ReaderInputStream.read() should return -1 (EOF) after the stream is
closed

Author: garydgregory

src/changes/changes.xml

@@ -81,6 +81,8 @@ The <action> type attribute can be add,update,fix,remove.
       <action dev="ggregory" type="fix"                due-to="Gary Gregory">ProxyInputStream.read() should return -1 (EOF) after the stream is closed.</action>
       <action dev="ggregory" type="fix"                due-to="Gary Gregory">RandomAccessFileInputStream.available() should return 0 after the stream is closed.</action>
       <action dev="ggregory" type="fix"                due-to="Gary Gregory">RandomAccessFileInputStream.read() should return -1 (EOF) after the stream is closed.</action>
+      <action dev="ggregory" type="fix"                due-to="Gary Gregory">ReaderInputStream.available() should return 0 after the stream is closed.</action>
+      <action dev="ggregory" type="fix"                due-to="Gary Gregory">ReaderInputStream.read() should return -1 (EOF) after the stream is closed.</action>
       <!-- UPDATE -->
       <action dev="ggregory" type="update"             due-to="Dependabot">Bump tests commons.bytebuddy.version from 1.14.13 to 1.14.17 #615, #621, #631, #635.</action>
       <action dev="ggregory" type="update"             due-to="Dependabot">Bump tests commons-codec:commons-codec from 1.16.1 to 1.17.0.</action>

src/main/java/org/apache/commons/io/input/ReaderInputStream.java

@@ -85,7 +85,7 @@
  * @see org.apache.commons.io.output.WriterOutputStream
  * @since 2.0
  */
-public class ReaderInputStream extends InputStream {
+public class ReaderInputStream extends AbstractInputStream {
 
     // @formatter:off
     /**
@@ -338,6 +338,14 @@ public ReaderInputStream(final Reader reader, final String charsetName, final in
         this(reader, Charsets.toCharset(charsetName), bufferSize);
     }
 
+    @Override
+    public int available() throws IOException {
+        if (encoderOut.hasRemaining()) {
+            return encoderOut.remaining();
+        }
+        return 0;
+    }
+
     /**
      * Closes the stream. This method will cause the underlying {@link Reader} to be closed.
      *
@@ -346,6 +354,7 @@ public ReaderInputStream(final Reader reader, final String charsetName, final in
     @Override
     public void close() throws IOException {
         reader.close();
+        super.close();
     }
 
     /**
@@ -399,6 +408,9 @@ CharsetEncoder getCharsetEncoder() {
      */
     @Override
     public int read() throws IOException {
+        if (isClosed()) {
+            return IOUtils.EOF;
+        }
         for (;;) {
             if (encoderOut.hasRemaining()) {
                 return encoderOut.get() & 0xFF;

src/test/java/org/apache/commons/io/input/ReaderInputStreamTest.java

@@ -73,6 +73,37 @@ static Stream<Arguments> charsetData() {
 
     private final Random random = new Random();
 
+    private ReaderInputStream createInputStream() throws IOException {
+        return ReaderInputStream.builder().setReader(new StringReader(TEST_STRING)).get();
+    }
+
+    @Test
+    public void testAvailableAfterClose() throws IOException {
+        try (InputStream inputStream = createInputStream()) {
+            inputStream.close();
+            assertEquals(0, inputStream.available());
+        }
+    }
+
+    @Test
+    public void testReasdAfterClose() throws IOException {
+        try (InputStream inputStream = createInputStream()) {
+            inputStream.close();
+            assertEquals(IOUtils.EOF, inputStream.read());
+        }
+    }
+
+    @Test
+    public void testAvailableAfterOpen() throws IOException {
+        try (InputStream inputStream = createInputStream()) {
+            // Nothing read, may block
+            assertEquals(0, inputStream.available());
+            // Read/block
+            inputStream.read();
+            assertEquals(TEST_STRING.length() - 1, inputStream.available());
+        }
+    }
+
     @Test
     @Timeout(value = 500, unit = TimeUnit.MILLISECONDS)
     public void testBufferSmallest() throws IOException {