Fixes end-of-input exception when decoding an empty json body

bcrowcs · Adrian Cole · commit 1f0464eba1b2 · 2015-07-10T11:05:24.000+02:00
No content to map due to end-of-input when decoding empty returns using JacksonDecoder. Added UnitTests to show JacksonDecoder error. Added unit test to GsonDecoder to verify behavior is as expected. Added a check for available inputStream data before trying to read into an Object. closes OpenFeign#247
diff --git a/gson/src/test/java/feign/gson/GsonCodecTest.java b/gson/src/test/java/feign/gson/GsonCodecTest.java
@@ -130,6 +130,14 @@ public void nullBodyDecodesToNull() throws Exception {
     assertNull(new GsonDecoder().decode(response, String.class));
   }
 
+  @Test
+  public void emptyBodyDecodesToNull() throws Exception {
+    Response response = Response.create(204, "OK",
+                                        Collections.<String, Collection<String>>emptyMap(),
+                                        new byte[0]);
+    assertNull(new GsonDecoder().decode(response, String.class));
+  }
+
   private String zonesJson = ""//
                              + "[\n"//
                              + "  {\n"//
diff --git a/jackson/src/main/java/feign/jackson/JacksonDecoder.java b/jackson/src/main/java/feign/jackson/JacksonDecoder.java
@@ -52,6 +52,9 @@ public Object decode(Response response, Type type) throws IOException {
     }
     InputStream inputStream = response.body().asInputStream();
     try {
+      if (inputStream.available() <= 0){
+        return null;
+      }
       return mapper.readValue(inputStream, mapper.constructType(type));
     } catch (RuntimeJsonMappingException e) {
       if (e.getCause() != null && e.getCause() instanceof IOException) {
diff --git a/jackson/src/test/java/feign/jackson/JacksonCodecTest.java b/jackson/src/test/java/feign/jackson/JacksonCodecTest.java
@@ -96,6 +96,14 @@ public void nullBodyDecodesToNull() throws Exception {
     assertNull(new JacksonDecoder().decode(response, String.class));
   }
 
+  @Test
+  public void emptyBodyDecodesToNull() throws Exception {
+    Response response = Response.create(204, "OK",
+                                        Collections.<String, Collection<String>>emptyMap(),
+                                        new byte[0]);
+    assertNull(new JacksonDecoder().decode(response, String.class));
+  }
+
   @Test
   public void customDecoder() throws Exception {
     JacksonDecoder decoder = new JacksonDecoder(
