Fix the argument check for account-generator

Concurrency parameter for account-generator command was accepting
negative values and zero.

This patch makes sure that when the account-generator is passed
a negative value or zero, it ends with an error.

Closes-Bug: #1811349
Partially-Implements: blueprint tempest-cli-unit-test-coverage
Change-Id: I4d7de89b2ad3ee91d113da3746fe393d8cce2aa2

releasenotes/notes/account-generator-accepts-positive-numbers-only-33a366a297494ef7.yaml

@@ -0,0 +1,7 @@
+---
+fixes:
+  - |
+   Concurrency parameter for account-generator command was accepting
+   negative values and zero. The concurrency parameter now accepts only
+   positive numbers. When a negative value or zero is passed to the
+   program then the program ends and help is displayed.

tempest/cmd/account_generator.py

@@ -97,6 +97,7 @@ To see help on specific argument, please do: ``tempest account-generator
 [OPTIONS] <accounts_file.yaml> -h``.
 """
 
+import argparse
 import os
 import traceback
 
@@ -199,6 +200,14 @@ def dump_accounts(resources, identity_version, account_file):
     LOG.info('%s generated successfully!', account_file)
 
 
+def positive_int(number):
+    number = int(number)
+    if number <= 0:
+        raise argparse.ArgumentTypeError("Concurrency value should be a "
+                                         "positive number")
+    return number
+
+
 def _parser_add_args(parser):
     parser.add_argument('-c', '--config-file',
                         metavar='/etc/tempest.conf',
@@ -228,7 +237,7 @@ def _parser_add_args(parser):
                         help='Resources tag')
     parser.add_argument('-r', '--concurrency',
                         default=1,
-                        type=int,
+                        type=positive_int,
                         required=False,
                         dest='concurrency',
                         help='Concurrency count')

tempest/tests/cmd/test_account_generator.py

@@ -337,3 +337,24 @@ class TestDumpAccountsV3(TestDumpAccountsV2):
     def setUp(self):
         self.mock_domains()
         super(TestDumpAccountsV3, self).setUp()
+
+
+class TestAccountGeneratorCliCheck(base.TestCase):
+
+    def setUp(self):
+        super(TestAccountGeneratorCliCheck, self).setUp()
+        self.account_generator = account_generator.TempestAccountGenerator(
+            app=mock.Mock(), app_args=mock.Mock())
+        self.parser = self.account_generator.get_parser("generator")
+
+    def test_account_generator_zero_concurrency(self):
+        error = self.assertRaises(
+            SystemExit, lambda: self.parser.parse_args(
+                ['-r', '0', 'accounts_file.yaml']))
+        self.assertTrue(error.code != 0)
+
+    def test_account_generator_negative_concurrency(self):
+        error = self.assertRaises(
+            SystemExit, lambda: self.parser.parse_args(
+                ['-r', '-1', 'accounts_file.yaml']))
+        self.assertTrue(error.code != 0)