Updated flake8 to fail if number of warnings is too high

.travis.yml

@@ -1,23 +1,41 @@
 # Infection Monkey travis.yml. See Travis documentation for information about this file structure.
 
 group: travis_latest
+
 language: python
+
 cache: pip
+
 python:
 - 3.7
+
 install:
 - pip install -r monkey/monkey_island/requirements.txt  # for unit tests
 - pip install flake8 pytest dlint  # for next stages
 - pip install -r monkey/infection_monkey/requirements_linux.txt  # for unit tests
+
 before_script:
-- flake8 . --count --select=E901,E999,F821,F822,F823 --show-source --statistics  # Check syntax errors
-- flake8 . --count --exit-zero --max-complexity=10 --max-line-length=127 --statistics  # warn about linter issues. --exit-zero
-  # means this stage will not fail the build. This is (hopefully) a temporary measure until all warnings are suppressed.
-- python monkey/monkey_island/cc/set_server_config.py testing  # Set the server config to `testing`, for the UTs to use
-  # mongomaock and pass.
+# Check syntax errors and fail the build if any are found.
+- flake8 . --count --select=E901,E999,F821,F822,F823 --show-source --statistics
+
+# Warn about linter issues.
+# --exit-zero forces Flake8 to use the exit status code 0 even if there are errors, which means this will NOT fail the build.
+# --count will print the total number of errors.
+# --statistics Count the number of occurrences of each error/warning code and print a report.
+# The output is redirected to a file.
+- flake8 . --count --exit-zero --max-complexity=10 --max-line-length=127 --statistics > flake8_warnings.txt
+# Display the linter issues
+- cat flake8_warnings.txt
+# Make sure that we haven't increased the amount of warnings.
+- test (`tail -n 1 flake8_warnings.txt` -lt 180)
+
+# Set the server config to `testing`, for the UTs to use mongomaock and pass.
+- python monkey/monkey_island/cc/set_server_config.py testing
+
 script:
 - cd monkey  # This is our source dir
 - python -m pytest  # Have to use `python -m pytest` instead of `pytest` to add "{$builddir}/monkey/monkey" to sys.path.
+
 notifications:
   slack:  # Notify to slack
       rooms: