Add the Pagination Utility to the Elasticache describe_cache_clusters model + response (#7500)

moto/elasticache/models.py

@@ -1,9 +1,10 @@
 from re import compile as re_compile
-from typing import Any, Dict, List, Optional, Tuple
+from typing import Any, Dict, List, Optional
 
 from moto.core.base_backend import BackendDict, BaseBackend
 from moto.core.common_models import BaseModel
 from moto.core.utils import utcnow
+from moto.utilities.paginator import paginate
 
 from ..moto_api._internal import mock_random
 from .exceptions import (
@@ -13,6 +14,7 @@ from .exceptions import (
     UserAlreadyExists,
     UserNotFound,
 )
+from .utils import PAGINATION_MODEL
 
 
 class User(BaseModel):
@@ -312,25 +314,24 @@ class ElastiCacheBackend(BaseBackend):
         self.cache_clusters[cache_cluster_id] = cache_cluster
         return cache_cluster
 
+    @paginate(PAGINATION_MODEL)
     def describe_cache_clusters(
         self,
         cache_cluster_id: str,
         max_records: int,
         marker: str,
-    ) -> Tuple[str, List[CacheCluster]]:
+    ) -> List[CacheCluster]:
-        if marker is None:
-            marker = str(mock_random.uuid4())
         if max_records is None:
             max_records = 100
         if cache_cluster_id:
             if cache_cluster_id in self.cache_clusters:
                 cache_cluster = self.cache_clusters[cache_cluster_id]
-                return marker, [cache_cluster]
+                return list([cache_cluster])
             else:
                 raise CacheClusterNotFound(cache_cluster_id)
         cache_clusters = list(self.cache_clusters.values())[:max_records]
 
-        return marker, cache_clusters
+        return cache_clusters
 
     def delete_cache_cluster(self, cache_cluster_id: str) -> CacheCluster:
         if cache_cluster_id:

moto/elasticache/responses.py

@@ -128,7 +128,8 @@ class ElastiCacheResponse(BaseResponse):
         cache_cluster_id = self._get_param("CacheClusterId")
         max_records = self._get_int_param("MaxRecords")
         marker = self._get_param("Marker")
-        marker, cache_clusters = self.elasticache_backend.describe_cache_clusters(
+
+        cache_clusters, marker = self.elasticache_backend.describe_cache_clusters(
             cache_cluster_id=cache_cluster_id,
             marker=marker,
             max_records=max_records,
@@ -347,7 +348,7 @@ DESCRIBE_CACHE_CLUSTERS_TEMPLATE = """<DescribeCacheClustersResponse xmlns="http
     <RequestId>1549581b-12b7-11e3-895e-1334aEXAMPLE</RequestId>
   </ResponseMetadata>
   <DescribeCacheClustersResult>
-    <Marker>{{ marker }}</Marker>
+    {% if marker %}<Marker>{{ marker }}</Marker>{% endif %}
     <CacheClusters>
 {% for cache_cluster in cache_clusters %}
       <member>

moto/elasticache/utils.py

@@ -0,0 +1,8 @@
+PAGINATION_MODEL = {
+    "describe_cache_clusters": {
+        "input_token": "marker",
+        "limit_key": "max_records",
+        "limit_default": 100,
+        "unique_attribute": "cache_cluster_id",
+    },
+}

tests/test_elasticache/test_elasticache.py

@@ -291,28 +291,31 @@ def test_create_duplicate_cache_cluster():
 def test_describe_all_cache_clusters():
     client = boto3.client("elasticache", region_name="us-east-2")
 
-    test_memcached_cache_cluster_exist = False
+    num_clusters = 5
-
+    match_number = 0
-    cache_cluster_id = "test-cache-cluster"
-    cache_cluster_engine = "memcached"
-    cache_cluster_num_cache_nodes = 5
 
+    for i in range(num_clusters):
         client.create_cache_cluster(
-        CacheClusterId=cache_cluster_id,
+            CacheClusterId=f"test-cache-cluster-{i}",
-        Engine=cache_cluster_engine,
+            Engine="memcached",
-        NumCacheNodes=cache_cluster_num_cache_nodes,
+            NumCacheNodes=5,
         )
 
     resp = client.describe_cache_clusters()
+    assert resp["ResponseMetadata"]["HTTPStatusCode"] == 200
 
     cache_clusters = resp["CacheClusters"]
+    # account for the default cluster created moto/elasticache/models.py line 148
+    del cache_clusters[0]
 
-    for cache_cluster in cache_clusters:
+    for i, cache_cluster in enumerate(cache_clusters):
-        if cache_cluster["CacheClusterId"] == cache_cluster_id:
+        if cache_cluster["CacheClusterId"] == f"test-cache-cluster-{i}":
-            test_memcached_cache_cluster_exist = True
+            match_number = match_number + 1
 
-    assert resp["ResponseMetadata"]["HTTPStatusCode"] == 200
+    if match_number == (num_clusters):
-    assert test_memcached_cache_cluster_exist
+        assert True
+    else:
+        assert False
 
 
 @mock_aws