Fix tests for pytest 3.3

[blueyed]

Fixes #550.

[codecov-io]

Codecov Report

Merging #552 into master will not change coverage.
The diff coverage is n/a.

@@          Coverage Diff          @@
##           master   #552   +/-   ##
=====================================
  Coverage      92%    92%           
=====================================
  Files          33     33           
  Lines        1627   1627           
  Branches      140    140           
=====================================
  Hits         1497   1497           
  Misses         93     93           
  Partials       37     37

Flag	Coverage Δ
#dj110	84.75% <ø> (ø)	⬆️
#dj111	86.04% <ø> (ø)	⬆️
#dj18	85.61% <ø> (ø)	⬆️
#dj19	84.63% <ø> (ø)	⬆️
#dj20	84.32% <ø> (ø)	⬆️
#djmaster	84.32% <ø> (ø)	⬆️
#mysql_innodb	84.26% <ø> (ø)	⬆️
#mysql_myisam	84.2% <ø> (ø)	⬆️
#postgres	87.64% <ø> (ø)	⬆️
#py27	89.36% <ø> (ø)	⬆️
#py34	84.63% <ø> (ø)	⬆️
#py35	84.75% <ø> (ø)	⬆️
#py36	84.81% <ø> (ø)	⬆️
#sqlite	86.1% <ø> (ø)	⬆️
#sqlite_file	84.63% <ø> (ø)	⬆️

Impacted Files	Coverage Δ
tests/test_unittest.py	100% <ø> (ø)	⬆️
tests/test_environment.py	100% <ø> (ø)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 4145f73...d55576a. Read the comment docs.