Unit test comparing response data raises TypeError

Question

I'm trying to write some unit tests for the example flaskr application. I want to check if a specific string is in the response. I keep getting a TypeError: 'str' does not support the buffer interface . Why am I getting this error and how should I fix it?

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ERROR: test_empty_db (__main__.FlaskrTestCase)
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Traceback (most recent call last):
  File "test_flaskr.py", line 31, in test_empty_db
    assert 'No entries here so far' in rv.data
TypeError: 'str' does not support the buffer interface

Answer 1

Response data from the test client is bytes, not unicode, data. In Python 3, this means you need to decode the data to compare it to a string, or compare it to a bytestring instead.

# compare bytes
assert b'No entries so far' in rv.data

# or decode to string
assert 'No entries so far' in rv.data.decode('utf8')