Update test case and nit changes

Author: wangmengyan95

Parse/src/main/java/com/parse/ParseFileController.java

@@ -114,7 +114,7 @@ public ParseFile.State then(Task<JSONObject> task) throws Exception {
 
         return newState;
       }
-    }, Task.BACKGROUND_EXECUTOR);
+    }, ParseExecutors.io());
   }
 
   public Task<ParseFile.State> saveAsync(
@@ -161,7 +161,7 @@ public ParseFile.State then(Task<JSONObject> task) throws Exception {
 
         return newState;
       }
-    }, Task.BACKGROUND_EXECUTOR);
+    }, ParseExecutors.io());
   }
 
   public Task<File> fetchAsync(

Parse/src/main/java/com/parse/ParseRESTFileCommand.java

@@ -62,6 +62,9 @@ public ParseRESTFileCommand build() {
 
   public ParseRESTFileCommand(Builder builder) {
     super(builder);
+    if (builder.file != null && builder.data != null) {
+      throw new IllegalArgumentException("File and data can not be set at the same time");
+    }
     this.data = builder.data;
     this.contentType = builder.contentType;
     this.file = builder.file;

Parse/src/test/java/com/parse/ParseFileControllerTest.java

@@ -186,11 +186,12 @@ public void testSaveAsyncSuccessWithFile() throws Exception {
     assertEquals("http://example.com", result.url());
     File cachedFile = new File(root, "new_file_name");
     assertTrue(cachedFile.exists());
+    assertTrue(file.exists());
     assertEquals("content", ParseFileUtils.readFileToString(cachedFile, "UTF-8"));
   }
 
   @Test
-  public void testSaveAsyncFailure() throws Exception {
+  public void testSaveAsyncFailureWithByteArray() throws Exception {
     // TODO(grantland): Remove once we no longer rely on retry logic.
     ParseRequest.setDefaultInitialRetryDelay(1L);
 
@@ -215,6 +216,34 @@ public void testSaveAsyncFailure() throws Exception {
     assertEquals(0, root.listFiles().length);
   }
 
+  @Test
+  public void testSaveAsyncFailureWithFile() throws Exception {
+    // TODO(grantland): Remove once we no longer rely on retry logic.
+    ParseRequest.setDefaultInitialRetryDelay(1L);
+
+    ParseHttpClient restClient = mock(ParseHttpClient.class);
+    when(restClient.execute(any(ParseHttpRequest.class))).thenThrow(new IOException());
+
+    File root = temporaryFolder.getRoot();
+    ParseFileController controller = new ParseFileController(restClient, root);
+
+    File file = temporaryFolder.newFile("test");
+    ParseFile.State state = new ParseFile.State.Builder()
+        .build();
+    Task<ParseFile.State> task = controller.saveAsync(state, file, null, null, null);
+    task.waitForCompletion();
+
+    // TODO(grantland): Abstract out command runner so we don't have to account for retries.
+    verify(restClient, times(5)).execute(any(ParseHttpRequest.class));
+    assertTrue(task.isFaulted());
+    Exception error = task.getError();
+    assertThat(error, instanceOf(ParseException.class));
+    assertEquals(ParseException.CONNECTION_FAILED, ((ParseException) error).getCode());
+    // Make sure the original file is not deleted and there is no cache file in the folder
+    assertEquals(1, root.listFiles().length);
+    assertTrue(file.exists());
+  }
+
   //endregion
 
   //region testFetchAsync