Add set_default_policy_version to the IAM backend (#3347)

* Adding set_default_policy_version

* Adding tests and reformatting

* Reformatting tests

moto/iam/models.py

@@ -125,9 +125,10 @@ class Policy(CloudFormationModel):
 
     def update_default_version(self, new_default_version_id):
         for version in self.versions:
+            if version.version_id == new_default_version_id:
+                version.is_default = True
             if version.version_id == self.default_version_id:
                 version.is_default = False
-                break
         self.default_version_id = new_default_version_id
 
     @property
@@ -1544,6 +1545,29 @@ class IAMBackend(BaseBackend):
 
         return self._filter_attached_policies(policies, marker, max_items, path_prefix)
 
+    def set_default_policy_version(self, policy_arn, version_id):
+        import re
+
+        if re.match("v[1-9][0-9]*(\.[A-Za-z0-9-]*)?", version_id) is None:
+            raise ValidationError(
+                "Value '{0}' at 'versionId' failed to satisfy constraint: Member must satisfy regular expression pattern: v[1-9][0-9]*(\.[A-Za-z0-9-]*)?".format(
+                    version_id
+                )
+            )
+
+        policy = self.get_policy(policy_arn)
+
+        for version in policy.versions:
+            if version.version_id == version_id:
+                policy.update_default_version(version_id)
+                return True
+
+        raise NoSuchEntity(
+            "Policy {0} version {1} does not exist or is not attachable.".format(
+                policy_arn, version_id
+            )
+        )
+
     def _filter_attached_policies(self, policies, marker, max_items, path_prefix):
         if path_prefix:
             policies = [p for p in policies if p.path.startswith(path_prefix)]

moto/iam/responses.py

@@ -175,6 +175,13 @@ class IamResponse(BaseResponse):
             roles=entity_roles, users=entity_users, groups=entity_groups
         )
 
+    def set_default_policy_version(self):
+        policy_arn = self._get_param("PolicyArn")
+        version_id = self._get_param("VersionId")
+        iam_backend.set_default_policy_version(policy_arn, version_id)
+        template = self.response_template(SET_DEFAULT_POLICY_VERSION_TEMPLATE)
+        return template.render()
+
     def create_role(self):
         role_name = self._get_param("RoleName")
         path = self._get_param("Path")
@@ -1010,6 +1017,13 @@ LIST_ENTITIES_FOR_POLICY_TEMPLATE = """<ListEntitiesForPolicyResponse>
 </ListEntitiesForPolicyResponse>"""
 
 
+SET_DEFAULT_POLICY_VERSION_TEMPLATE = """<SetDefaultPolicyVersionResponse xmlns="https://iam.amazonaws.com/doc/2010-05-08/">
+  <ResponseMetadata>
+    <RequestId>35f241af-3ebc-11e4-9d0d-6f969EXAMPLE</RequestId>
+  </ResponseMetadata>
+</SetDefaultPolicyVersionResponse>"""
+
+
 ATTACH_ROLE_POLICY_TEMPLATE = """<AttachRolePolicyResponse>
   <ResponseMetadata>
     <RequestId>7a62c49f-347e-4fc4-9331-6e8eEXAMPLE</RequestId>

tests/test_iam/test_iam.py

@@ -549,6 +549,59 @@ def test_set_default_policy_version():
     versions.get("Versions")[2].get("Document").should.equal(json.loads(MOCK_POLICY_3))
     versions.get("Versions")[2].get("IsDefaultVersion").should.be.ok
 
+    conn.set_default_policy_version(
+        PolicyArn="arn:aws:iam::{}:policy/TestSetDefaultPolicyVersion".format(
+            ACCOUNT_ID
+        ),
+        VersionId="v1",
+    )
+    versions = conn.list_policy_versions(
+        PolicyArn="arn:aws:iam::{}:policy/TestSetDefaultPolicyVersion".format(
+            ACCOUNT_ID
+        )
+    )
+    versions.get("Versions")[0].get("Document").should.equal(json.loads(MOCK_POLICY))
+    versions.get("Versions")[0].get("IsDefaultVersion").should.be.ok
+    versions.get("Versions")[1].get("Document").should.equal(json.loads(MOCK_POLICY_2))
+    versions.get("Versions")[1].get("IsDefaultVersion").shouldnt.be.ok
+    versions.get("Versions")[2].get("Document").should.equal(json.loads(MOCK_POLICY_3))
+    versions.get("Versions")[2].get("IsDefaultVersion").shouldnt.be.ok
+
+    # Set default version for non-existing policy
+    conn.set_default_policy_version.when.called_with(
+        PolicyArn="arn:aws:iam::{}:policy/TestNonExistingPolicy".format(ACCOUNT_ID),
+        VersionId="v1",
+    ).should.throw(
+        ClientError,
+        "Policy arn:aws:iam::{}:policy/TestNonExistingPolicy not found".format(
+            ACCOUNT_ID
+        ),
+    )
+
+    # Set default version for incorrect version
+    conn.set_default_policy_version.when.called_with(
+        PolicyArn="arn:aws:iam::{}:policy/TestSetDefaultPolicyVersion".format(
+            ACCOUNT_ID
+        ),
+        VersionId="wrong_version_id",
+    ).should.throw(
+        ClientError,
+        "Value 'wrong_version_id' at 'versionId' failed to satisfy constraint: Member must satisfy regular expression pattern: v[1-9][0-9]*(\.[A-Za-z0-9-]*)?",
+    )
+
+    # Set default version for non-existing version
+    conn.set_default_policy_version.when.called_with(
+        PolicyArn="arn:aws:iam::{}:policy/TestSetDefaultPolicyVersion".format(
+            ACCOUNT_ID
+        ),
+        VersionId="v4",
+    ).should.throw(
+        ClientError,
+        "Policy arn:aws:iam::{}:policy/TestSetDefaultPolicyVersion version v4 does not exist or is not attachable.".format(
+            ACCOUNT_ID
+        ),
+    )
+
 
 @mock_iam
 def test_get_policy():