Changes to look ahead in isBatchedQuery (#62)

Simple change to ensure that the readlimit passed into InputStream.mark matches the length of the read buffer. This ensures that when InputStream.reset is called the stream is reset correctly.

A test has also been added to ensure this behaviour.

Author: briancullen

src/main/java/graphql/servlet/GraphQLServlet.java

@@ -439,11 +439,12 @@ private boolean isBatchedQuery(InputStream inputStream) throws IOException {
             return false;
         }
 
+        final int BUFFER_LENGTH = 128;
         ByteArrayOutputStream result = new ByteArrayOutputStream();
-        byte[] buffer = new byte[128];
+        byte[] buffer = new byte[BUFFER_LENGTH];
         int length;
 
-        inputStream.mark(0);
+        inputStream.mark(BUFFER_LENGTH);
         while ((length = inputStream.read(buffer)) != -1) {
             result.write(buffer, 0, length);
             String chunk = result.toString();

src/test/groovy/graphql/servlet/GraphQLServletSpec.groovy

@@ -13,6 +13,8 @@ import org.springframework.mock.web.MockHttpServletResponse
 import spock.lang.Shared
 import spock.lang.Specification
 
+import javax.servlet.ServletInputStream
+import javax.servlet.http.HttpServletRequest
 /**
  * @author Andrew Potter
  */
@@ -715,4 +717,26 @@ class GraphQLServletSpec extends Specification {
         expect:
             servlet.getMapper().writeValueAsString(ExecutionTypeInfo.newTypeInfo().type(new GraphQLNonNull(Scalars.GraphQLString)).build()) != "{}"
     }
+
+    def "isBatchedQuery check uses buffer length as read limit"() {
+        setup:
+            HttpServletRequest mockRequest = Mock()
+            ServletInputStream mockInputStream = Mock()
+
+            mockInputStream.markSupported() >> true
+            mockRequest.getInputStream() >> mockInputStream
+            mockRequest.getMethod() >> "POST"
+
+        when:
+            servlet.doPost(mockRequest, response)
+
+        then:
+            1 * mockInputStream.mark(128)
+
+        then:
+            1 * mockInputStream.read({ it.length == 128 }) >> -1
+
+        then:
+            1 * mockInputStream.reset()
+    }
 }