Fix test dependencies

[chenjr0719]

Notice Travis CI did not pass at #1457, and the reason is current version of pytest-cov(2.6.1) use pytest>=3.6 in install _requires(see here). This is conflict with Sanic's test_requires(it use pytest==3.3.2). Set pytest-cov==2.6.0 in test_requires and tox.ini can fix this issue.

BTW, remove pytest==3.3.2 is also a possible solution. But I don't know why use this version in test_requires, any idea?

[codecov]

Codecov Report

Merging #1463 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #1463   +/-   ##
=======================================
  Coverage   91.38%   91.38%           
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  Files          17       17           
  Lines        1718     1718           
  Branches      325      325           
=======================================
  Hits         1570     1570           
  Misses        123      123           
  Partials       25       25

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[harshanarayana]

@chenjr0719 Nice catch.

[yunstanford]

Thanks for the fix, I've fixed this locally, but didn't push it out. And I'm thinking we should push forward, instead of backpining.

[harshanarayana]

@chenjr0719 Logically speaking, we only need tox in our tests_require in setup.py if you are running tests inside the tox environment. However, if you choose to run the tests outside the tox context, you need the bare minimum requirements in setup.py.

[harshanarayana]

Move pytest to the latest version instead maybe?

[chenjr0719]

@yunstanford Agreed, let me see is there any error after remove pinned version of pytest.

@harshanarayana I know, I just make them consistent to make sure this issue will not happen either using tox or outside the tox.