Move cli interface code in package

app/tests/__init__.py

@@ -0,0 +1,5 @@
+from flask import Blueprint
+
+
+bp = Blueprint('tests', __name__)
+from . import cli

app/tests/cli.py

@@ -0,0 +1,9 @@
+from unittest import TestLoader, TextTestRunner
+from unittest.suite import TestSuite
+from . import bp
+
+@bp.cli.command('run')
+def run_test():
+    ''' Run unit tests. '''
+    tests: TestSuite = TestLoader().discover('tests')
+    TextTestRunner(verbosity=2).run(tests)