From c51ff9bb5f39f15c09473b56948c44f819e37fb3 Mon Sep 17 00:00:00 2001
From: Jonas <jonas@bulik.dev>
Date: Tue, 26 Jul 2022 03:26:30 +0200
Subject: [PATCH] IOT: fix increment policy version ids (#5296)

---
 moto/iot/models.py                  | 18 ++++++++++---
 tests/test_iot/test_iot_policies.py | 39 +++++++++++++++++++++++++++++
 2 files changed, 53 insertions(+), 4 deletions(-)

diff --git a/moto/iot/models.py b/moto/iot/models.py
index 46d37c62e..c3593cebc 100644
--- a/moto/iot/models.py
+++ b/moto/iot/models.py
@@ -216,6 +216,7 @@ class FakePolicy(BaseModel):
         self.arn = f"arn:aws:iot:{region_name}:{get_account_id()}:policy/{name}"
         self.default_version_id = default_version_id
         self.versions = [FakePolicyVersion(self.name, document, True, region_name)]
+        self._max_version_id = self.versions[0]._version_id
 
     def to_get_dict(self):
         return {
@@ -238,16 +239,20 @@ class FakePolicy(BaseModel):
 
 
 class FakePolicyVersion(object):
-    def __init__(self, policy_name, document, is_default, region_name):
+    def __init__(self, policy_name, document, is_default, region_name, version_id=1):
         self.name = policy_name
         self.arn = f"arn:aws:iot:{region_name}:{get_account_id()}:policy/{policy_name}"
         self.document = document or {}
         self.is_default = is_default
-        self.version_id = "1"
+        self._version_id = version_id
 
         self.create_datetime = time.mktime(datetime(2015, 1, 1).timetuple())
         self.last_modified_datetime = time.mktime(datetime(2015, 1, 2).timetuple())
 
+    @property
+    def version_id(self):
+        return str(self._version_id)
+
     def to_get_dict(self):
         return {
             "policyName": self.name,
@@ -1047,11 +1052,16 @@ class IoTBackend(BaseBackend):
             raise ResourceNotFoundException()
         if len(policy.versions) >= 5:
             raise VersionsLimitExceededException(policy_name)
+
+        policy._max_version_id += 1
         version = FakePolicyVersion(
-            policy_name, policy_document, set_as_default, self.region_name
+            policy_name,
+            policy_document,
+            set_as_default,
+            self.region_name,
+            version_id=policy._max_version_id,
         )
         policy.versions.append(version)
-        version.version_id = "{0}".format(len(policy.versions))
         if set_as_default:
             self.set_default_policy_version(policy_name, version.version_id)
         return version
diff --git a/tests/test_iot/test_iot_policies.py b/tests/test_iot/test_iot_policies.py
index 662bce869..7021c701e 100644
--- a/tests/test_iot/test_iot_policies.py
+++ b/tests/test_iot/test_iot_policies.py
@@ -241,6 +241,45 @@ def test_policy_versions(iot_client):
     err["Message"].should.equal("Cannot delete the default version of a policy")
 
 
+def test_policy_versions_increment_beyond_5(iot_client, policy):
+    """
+    Version ids increment by one each time.
+
+    Previously there was a bug where the version id was not incremented beyond 5.
+    This prevents a regression.
+    """
+    policy_name = policy["policyName"]
+
+    for v in range(2, 11):
+        new_version = iot_client.create_policy_version(
+            policyName=policy_name,
+            policyDocument=json.dumps({"version": f"version_{v}"}),
+            setAsDefault=True,
+        )
+        new_version.should.have.key("policyVersionId").which.should.equal(str(v))
+        iot_client.delete_policy_version(
+            policyName=policy_name, policyVersionId=str(v - 1)
+        )
+
+
+def test_policy_versions_increment_even_after_version_delete(iot_client, policy):
+    """Version ids increment even if the max version was deleted."""
+
+    policy_name = policy["policyName"]
+
+    new_version = iot_client.create_policy_version(
+        policyName=policy_name,
+        policyDocument=json.dumps({"version": "version_2"}),
+    )
+    new_version.should.have.key("policyVersionId").which.should.equal("2")
+    iot_client.delete_policy_version(policyName=policy_name, policyVersionId="2")
+    third_version = iot_client.create_policy_version(
+        policyName=policy_name,
+        policyDocument=json.dumps({"version": "version_3"}),
+    )
+    third_version.should.have.key("policyVersionId").which.should.equal("3")
+
+
 def test_delete_policy_validation(iot_client):
     doc = """{
     "Version": "2012-10-17",