Added test case for IIOOutputStreamAdapter + fixed bug in flush method.

Strengthened tests for IIOInputStreamAdapter
Minor clean up of the code.

imageio/imageio-core/src/main/java/com/twelvemonkeys/imageio/util/IIOInputStreamAdapter.java

@@ -28,6 +28,8 @@
 
 package com.twelvemonkeys.imageio.util;
 
+import com.twelvemonkeys.lang.Validate;
+
 import javax.imageio.stream.ImageInputStream;
 import java.io.IOException;
 import java.io.InputStream;
@@ -75,16 +77,12 @@ class IIOInputStreamAdapter extends InputStream {
     }
 
     private IIOInputStreamAdapter(ImageInputStream pInput, long pLength, boolean pHasLength) {
-        if (pInput == null) {
-            throw new IllegalArgumentException("stream == null");
-        }
-        if (pHasLength && pLength < 0) {
-            throw new IllegalArgumentException("length < 0");
-        }
+        Validate.notNull(pInput, "stream");
+        Validate.isTrue(!pHasLength || pLength >= 0, pLength, "length < 0: %f");
 
         input = pInput;
-        hasLength = pHasLength;
         left = pLength;
+        hasLength = pHasLength;
     }
 
 
@@ -105,6 +103,7 @@ class IIOInputStreamAdapter extends InputStream {
         if (hasLength) {
             return left > 0 ? (int) Math.min(Integer.MAX_VALUE, left) : 0;
         }
+
         return 0; // We don't really know, so we say 0 to be safe.
     }
 

imageio/imageio-core/src/main/java/com/twelvemonkeys/imageio/util/IIOOutputStreamAdapter.java

@@ -28,6 +28,8 @@
 
 package com.twelvemonkeys.imageio.util;
 
+import com.twelvemonkeys.lang.Validate;
+
 import javax.imageio.stream.ImageOutputStream;
 import java.io.IOException;
 import java.io.OutputStream;
@@ -43,27 +45,40 @@ class IIOOutputStreamAdapter extends OutputStream {
     private ImageOutputStream output;
 
     public IIOOutputStreamAdapter(final ImageOutputStream pOutput) {
+        Validate.notNull(pOutput, "stream == null");
+
         output = pOutput;
     }
 
     @Override
     public void write(final byte[] pBytes) throws IOException {
+        assertOpen();
         output.write(pBytes);
     }
 
     @Override
     public void write(final byte[] pBytes, final int pOffset, final int pLength) throws IOException {
+        assertOpen();
         output.write(pBytes, pOffset, pLength);
     }
 
     @Override
     public void write(final int pByte) throws IOException {
+        assertOpen();
         output.write(pByte);
     }
 
     @Override
     public void flush() throws IOException {
-        output.flush();
+        // NOTE: The contract of OutputStream.flush is very different from ImageOutputStream.flush. We can't delegate.
+        // TODO: Fulfill the contract of OutputStream.flush? This seems to be good enough for now.
+        assertOpen();
+    }
+
+    private void assertOpen() throws IOException {
+        if (output == null) {
+            throw new IOException("stream already closed");
+        }
     }
 
     @Override