Add Pagination for Organizations:ListAccountsForParent

Closes #5034

moto/organizations/models.py

@@ -514,15 +514,16 @@ class OrganizationsBackend(BaseBackend):
         accounts = sorted(accounts, key=lambda x: x["JoinedTimestamp"])
         return accounts
 
+    @paginate(pagination_model=PAGINATION_MODEL)
     def list_accounts_for_parent(self, **kwargs):
-        parent_id = self.validate_parent_id(kwargs["ParentId"])
-        return dict(
-            Accounts=[
+        parent_id = self.validate_parent_id(kwargs["parent_id"])
+        accounts = [
             account.describe()
             for account in self.accounts
             if account.parent_id == parent_id
         ]
-        )
+        accounts = sorted(accounts, key=lambda x: x["JoinedTimestamp"])
+        return accounts
 
     def move_account(self, **kwargs):
         new_parent_id = self.validate_parent_id(kwargs["DestinationParentId"])

moto/organizations/responses.py

@@ -109,9 +109,16 @@ class OrganizationsResponse(BaseResponse):
         return json.dumps(response)
 
     def list_accounts_for_parent(self):
-        return json.dumps(
-            self.organizations_backend.list_accounts_for_parent(**self.request_params)
+        max_results = self._get_int_param("MaxResults")
+        next_token = self._get_param("NextToken")
+        parent_id = self._get_param("ParentId")
+        accounts, next_token = self.organizations_backend.list_accounts_for_parent(
+            max_results=max_results, next_token=next_token, parent_id=parent_id
         )
+        response = {"Accounts": accounts}
+        if next_token:
+            response["NextToken"] = next_token
+        return json.dumps(response)
 
     def move_account(self):
         return json.dumps(

moto/organizations/utils.py

@@ -41,6 +41,13 @@ PAGINATION_MODEL = {
         "result_key": "Accounts",
         "unique_attribute": "JoinedTimestamp",
     },
+    "list_accounts_for_parent": {
+        "input_token": "next_token",
+        "limit_key": "max_results",
+        "limit_default": 20,
+        "result_key": "Accounts",
+        "unique_attribute": "JoinedTimestamp",
+    },
     "list_organizational_units_for_parent": {
         "input_token": "next_token",
         "limit_key": "max_results",

tests/test_organizations/test_organizations_boto3.py

@@ -327,6 +327,28 @@ def test_list_accounts_for_parent():
     account_id.should.be.within([account["Id"] for account in response["Accounts"]])
 
 
+@mock_organizations
+def test_list_accounts_for_parent_pagination():
+    client = boto3.client("organizations", region_name="us-east-1")
+    client.create_organization(FeatureSet="ALL")
+    root_id = client.list_roots()["Roots"][0]["Id"]
+    response = client.list_accounts_for_parent(ParentId=root_id)
+    response.should_not.have.key("NextToken")
+    num_existing_accounts = len(response["Accounts"])
+    for i in range(num_existing_accounts, 21):
+        name = mockname + str(i)
+        email = name + "@" + mockdomain
+        client.create_account(AccountName=name, Email=email)
+    response = client.list_accounts_for_parent(ParentId=root_id)
+    len(response["Accounts"]).should.be.greater_than_or_equal_to(i)
+
+    paginator = client.get_paginator("list_accounts_for_parent")
+    page_iterator = paginator.paginate(MaxResults=5, ParentId=root_id)
+    for page in page_iterator:
+        len(page["Accounts"]).should.be.lower_than_or_equal_to(5)
+    page["Accounts"][-1]["Name"].should.contain("20")
+
+
 @mock_organizations
 def test_move_account():
     client = boto3.client("organizations", region_name="us-east-1")