added default content type

src/test/java/org/scribe/model/ConnectionStub.java

@@ -22,6 +22,12 @@ public class ConnectionStub extends HttpURLConnection
     headers.put(key, value);
   }
 
+  @Override
+  public String getRequestProperty(String s)
+  {
+    return headers.get(s);
+  }
+
   public Map<String, String> getHeaders()
   {
     return headers;

src/test/java/org/scribe/model/RequestTest.java

@@ -6,7 +6,6 @@ import org.junit.*;
 
 public class RequestTest
 {
-
   private Request getRequest;
   private Request postRequest;
   private ConnectionStub connection;
@@ -80,4 +79,42 @@ public class RequestTest
   {
     assertTrue(getRequest.getQueryStringParams().get("other param").equals("value with spaces"));
   }
+
+  @Test
+  public void shouldAutomaticallyAddContentTypeForPostRequestsWithBytePayload()
+  {
+    postRequest.addPayload("PAYLOAD".getBytes());
+    postRequest.send();
+    assertEquals(Request.DEFAULT_CONTENT_TYPE, connection.getHeaders().get("Content-Type"));
+  }
+
+  @Test
+  public void shouldAutomaticallyAddContentTypeForPostRequestsWithStringPayload()
+  {
+    postRequest.addPayload("PAYLOAD");
+    postRequest.send();
+    assertEquals(Request.DEFAULT_CONTENT_TYPE, connection.getHeaders().get("Content-Type"));
+  }
+
+  @Test
+  public void shouldAutomaticallyAddContentTypeForPostRequestsWithBodyParameters()
+  {
+    postRequest.send();
+    assertEquals(Request.DEFAULT_CONTENT_TYPE, connection.getHeaders().get("Content-Type"));
+  }
+
+  @Test
+  public void shouldBeAbleToOverrideItsContentType()
+  {
+    postRequest.addHeader("Content-Type", "my-content-type");
+    postRequest.send();
+    assertEquals("my-content-type", connection.getHeaders().get("Content-Type"));
+  }
+
+  @Test
+  public void shouldNotAddContentTypeForGetRequests()
+  {
+    getRequest.send();
+    assertFalse(connection.getHeaders().containsKey("Content-Type"));
+  }
 }