Add pytest to pre-commit

.pre-commit-config.yaml

@@ -33,3 +33,13 @@ repos:
     hooks:
       - id: eslint
         args: ["monkey/monkey_island/cc/ui/src/", "--fix", "--max-warnings=0"]
+  - repo: local
+    hooks:
+    -   id: pytest
+        name: pytest
+        entry: bash -c "cd monkey && pytest"
+        language: system
+        pass_filenames: false
+        # alternatively you could `types: [python]` so it only runs when python files change
+        # though tests might be invalidated if you were to say change a data file
+        always_run: true