Update .travis.yml

Author: slarse

.travis.yml

@@ -1,26 +1,22 @@
 language: python
 cache: pip
 python:
-    - 2.7
     - 3.6
-    #- nightly
-    #- pypy
-    #- pypy3
 matrix:
     allow_failures:
         - python: nightly
         - python: pypy
         - python: pypy3
 install:
-    #- pip install -r requirements.txt
-    - pip install flake8  # pytest  # add another testing frameworks later
+    - pip install flake8
+    - pip install -e .[TEST]
 before_script:
     # stop the build if there are Python syntax errors or undefined names
     - flake8 . --count --select=E901,E999,F821,F822,F823 --show-source --statistics
     # exit-zero treats all errors as warnings.  The GitHub editor is 127 chars wide
     - flake8 . --count --exit-zero --max-complexity=10 --max-line-length=127 --statistics
 script:
-    - true  # pytest --capture=sys  # add other tests here
+    - pytest tests --cov thealgorithms --cov-branch
 notifications:
     on_success: change
-    on_failure: change  # `always` will be the setting once code changes slow down
+    on_failure: change