fix coverage for pytest runner

.travis.yml

@@ -76,13 +76,13 @@ before_script:
   - mongo --eval 'db.version();'    # Make sure mongo is awake
 
 script:
-  - tox -e $(echo py$TRAVIS_PYTHON_VERSION-mg$PYMONGO | tr -d . | sed -e 's/pypypy/pypy/') #-- --with-coverage
+  - tox -e $(echo py$TRAVIS_PYTHON_VERSION-mg$PYMONGO | tr -d . | sed -e 's/pypypy/pypy/') -- -a "--cov=mongoengine"
 
 # For now only submit coveralls for Python v2.7. Python v3.x currently shows
 # 0% coverage. That's caused by 'use_2to3', which builds the py3-compatible
 # code in a separate dir and runs tests on that.
 after_success:
-- if [[ $TRAVIS_PYTHON_VERSION == '2.7' ]]; then coveralls --verbose; fi
+- if [[ $TRAVIS_PYTHON_VERSION == '2.7' ]]; then cat .coverage & coveralls --verbose; fi
 
 notifications:
   irc: irc.freenode.org#mongoengine

setup.py

@@ -113,7 +113,13 @@ CLASSIFIERS = [
 
 extra_opts = {
     "packages": find_packages(exclude=["tests", "tests.*"]),
-    "tests_require": ["pytest<5.0", "coverage==4.2", "blinker", "Pillow>=2.0.0"],
+    "tests_require": [
+        "pytest<5.0",
+        "pytest-cov",
+        "coverage",
+        "blinker",
+        "Pillow>=2.0.0",
+    ],
 }
 if sys.version_info[0] == 3:
     extra_opts["use_2to3"] = True