title: UnicodeDecodeError: 'utf-8' codec can't decode byte 0xb9 in position 14: invalid start byte
body: <p>I am doing a File upload test with Django REST.<br>
  Python3.6.2<br>
  Django1.11<br>
  djangorestframework==3.6.4<br>
  Excel-OSX 15.38(170902)<br>
  OSX 10.12.6<br><br></p>
  
  <p>It used to be done successfully with ordinary photo files.<br> 
  This time is Excel file from website. Here is my testcase copy from references.</p>
  
  <pre><code> def test_upload_and_process_data_complete_case(self):
          from django.core.files import File
          from django.core.files.uploadedfile import SimpleUploadedFile
          from soken_web.apps.imported_files.models import ImportFile
  
          file = File(open(str(settings.BASE_DIR) + '/apps/zipcodes/complete.xlsx'))
          uploaded_file = SimpleUploadedFile('new_image.xlsx', file.read(), content_type='multipart/form-data')
  
          data = {
              'attribute': {'author': 'Sigh'},
              'type': ImportFile.FileType.zipcode,
              'file': uploaded_file
          }
          response = self.client.post(reverse('api:import_file-list'), data, format='multipart')
          response.render()
  
          self.assertEqual(status.HTTP_201_CREATED, response.status_code)
  </code></pre>
  
  <p>Like a copy cat. Except this time I download a mock file from <a href="https://www.mockaroo.com/" rel="nofollow noreferrer">https://www.mockaroo.com/</a>.</p>
  
  <p>Here is the error raises when I execute <code>file.read()</code></p>
  
  <pre><code>file
  &lt;File: /Users/el/Code/norak-cutter/soken/soken-web/soken_web/apps/zipcodes/complete.xlsx&gt;
  file.read()
  Traceback (most recent call last):
    File "/Users/el/Library/Application Support/JetBrains/Toolbox/apps/PyCharm-P/ch-0/172.3968.37/PyCharm.app/Contents/helpers/pydev/_pydevd_bundle/pydevd_exec2.py", line 3, in Exec
      exec(exp, global_vars, local_vars)
    File "&lt;input&gt;", line 1, in &lt;module&gt;
    File "/Users/el/.pyenv/versions/3.6.2/lib/python3.6/codecs.py", line 321, in decode
      (result, consumed) = self._buffer_decode(data, self.errors, final)
  UnicodeDecodeError: 'utf-8' codec can't decode byte 0xb9 in position 14: invalid start byte
  </code></pre>
  
  <p><strong>Confirmations:</strong><br>
  1. I can upload file from my web browser<br>
  2. I can open that file without any warning messages.<br></p>
  
  <p><strong>Question:</strong><br>
  Are there anything I forgot to concern?</p>
  
  <p><strong>References:</strong><br>
  <a href="https://stackoverflow.com/questions/24201676/how-can-i-test-binary-file-uploading-with-django-rest-frameworks-test-client">How can I test binary file uploading with django-rest-framework&#39;s test client?</a><br>
  <a href="https://stackoverflow.com/questions/46426734/django-rest-unittest-no-file-was-submitted">Django REST UnitTest No file was submitted</a></p>