Fix occasional test failure - should always return 0 for read length == 0

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/io/trunk@1300238 13f79535-47bb-0310-9956-ffa450edef68

Author: sebbASF

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

@@ -117,7 +117,10 @@ public int read(byte[] b, int off, int len) throws IOException {
         if (len < 0 || (off + len) > b.length) {
             throw new IndexOutOfBoundsException("Array Size=" + b.length +
                     ", offset=" + off + ", length=" + len);
-        }        
+        }
+        if (len == 0) {
+            return 0; // must return 0 for zero length read
+        }
         if (!this.bbuf.hasRemaining() && !this.cbuf.hasRemaining()) {
             return -1;
         }

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

@@ -109,6 +109,13 @@ public void testReadZero() throws Exception {
         byte[] bytes = new byte[30];
         assertEquals(0, r.read(bytes, 0, 0));
     }
+
+    @Test
+    public void testReadZeroEmptyString() throws Exception {
+        InputStream r = new CharSequenceInputStream("", "UTF-8");
+        byte[] bytes = new byte[30];
+        assertEquals(0, r.read(bytes, 0, 0));
+    }
 
     @Test
     public void testCharsetMismatchInfiniteLoop() throws IOException {