Fixed bug with incorrectly computed free buffer capacity.

Author: svobol13

src/main/java/com/jsoniter/IterImplForStreaming.java

@@ -277,7 +277,7 @@ private static boolean keepSkippedBytesThenRead(JsonIterator iter) throws IOExce
         int offset = iter.tail - iter.skipStartedAt;
         byte[] srcBuffer = iter.buf;
         // Check there is no unused buffer capacity
-        if (iter.buf.length - iter.tail == 0) {
+        if ((getUnusedBufferByteCount(iter)) == 0) {
           // If auto expand buffer enabled, then create larger buffer
           if (iter.autoExpandBufferStep > 0) {
             iter.buf = new byte[iter.buf.length + iter.autoExpandBufferStep];
@@ -301,6 +301,11 @@ private static boolean keepSkippedBytesThenRead(JsonIterator iter) throws IOExce
         return true;
     }
 
+    private static int getUnusedBufferByteCount(JsonIterator iter) {
+        // Get bytes from 0 to skipStart + from tail till end
+        return iter.buf.length - iter.tail + iter.skipStartedAt;
+    }
+
     final static byte readByte(JsonIterator iter) throws IOException {
         if (iter.head == iter.tail) {
             if (!loadMore(iter)) {

src/test/java/com/jsoniter/IterImplForStreamingTest.java

@@ -2,6 +2,7 @@
 
 import com.jsoniter.any.Any;
 import com.jsoniter.spi.JsonException;
+import java.io.ByteArrayInputStream;
 import java.io.IOException;
 import java.io.InputStream;
 import junit.framework.TestCase;
@@ -35,7 +36,7 @@ public void testLoadMore() throws IOException {
 		// Check buffer was not expanded
 		assertEquals(initialBufferSize, jsonIterator.buf.length);
 
-		// Case #2: Data does fit into initial buffer, autoresizing off
+		// Case #2: Data does not fit into initial buffer, autoresizing off
 		initialBufferSize = originalContent.length() / 2;
 		jsonIterator = JsonIterator.parse(getSluggishInputStream(src), initialBufferSize, 0);
 		jsonIterator.readObject();
@@ -59,6 +60,15 @@ public void testLoadMore() throws IOException {
 		assertEquals(originalContent, parsedString.toString());
 		// Check buffer was expanded exactly once
 		assertEquals(initialBufferSize + autoExpandBufferStep, jsonIterator.buf.length);
+
+		// Case #4: Data does not fit (but largest string does) into initial buffer, autoresizing on
+		initialBufferSize = originalContent.length() + 2;
+		jsonIterator = JsonIterator.parse(new ByteArrayInputStream(src), initialBufferSize, 0);
+		jsonIterator.readObject();
+		parsedString = jsonIterator.readAny();
+		assertEquals(originalContent, parsedString.toString());
+		// Check buffer was expanded exactly once
+		assertEquals(initialBufferSize, jsonIterator.buf.length);
 	}
 
 	private static InputStream getSluggishInputStream(final byte[] src) {