Add pytest-cov plugin to measure code coverage

.gitignore

@@ -5,3 +5,4 @@ __pycache__
 settings*.cfg
 /data
 .cache
+.coverage

docker-compose-test.yml

@@ -4,7 +4,7 @@ services:
     image: inventory
     container_name: inventory_web_test
     build: .
-    command: pytest -v
+    command: pytest --cov=app -v
     volumes:
       - .:/app
     depends_on:

environment.yml

@@ -8,6 +8,7 @@ dependencies:
 - conda-forge::certifi=2017.4.17=py36_0
 - conda-forge::click=6.7=py36_0
 - conda-forge::colorama=0.3.9=py36_0
+- conda-forge::coverage=4.4.1=py36_0
 - conda-forge::flask=0.12.2=py36_0
 - conda-forge::flask-login=0.4.0=py36_0
 - conda-forge::flask-sqlalchemy=2.2=py36_1
@@ -30,6 +31,7 @@ dependencies:
 - conda-forge::psycopg2=2.7.1=py36_0
 - conda-forge::py=1.4.34=py36_0
 - conda-forge::pytest=3.2.1=py36_0
+- conda-forge::pytest-cov=2.5.1=py36_0
 - conda-forge::python=3.6.1=3
 - conda-forge::python-dateutil=2.6.0=py36_0
 - conda-forge::python-editor=1.0.3=py36_0