DynamoDB: describe_table() - return correct error msg (#5997)

moto/dynamodb/exceptions.py

@@ -4,12 +4,15 @@ from moto.core.exceptions import JsonRESTError
 from moto.dynamodb.limits import HASH_KEY_MAX_LENGTH, RANGE_KEY_MAX_LENGTH
 
 
+ERROR_TYPE_PREFIX = "com.amazonaws.dynamodb.v20120810#"
+
+
 class DynamodbException(JsonRESTError):
     pass
 
 
 class MockValidationException(DynamodbException):
-    error_type = "com.amazonaws.dynamodb.v20111205#ValidationException"
+    error_type = ERROR_TYPE_PREFIX + "ValidationException"
 
     def __init__(self, message: str):
         super().__init__(MockValidationException.error_type, message=message)
@@ -190,7 +193,7 @@ class IncorrectDataType(MockValidationException):
 
 
 class ConditionalCheckFailed(DynamodbException):
-    error_type = "com.amazonaws.dynamodb.v20111205#ConditionalCheckFailedException"
+    error_type = ERROR_TYPE_PREFIX + "ConditionalCheckFailedException"
 
     def __init__(self, msg: Optional[str] = None):
         super().__init__(
@@ -279,44 +282,47 @@ class TooManyAddClauses(InvalidUpdateExpression):
 
 
 class ResourceNotFoundException(JsonRESTError):
-    def __init__(self, msg: Optional[str] = None):
-        err = "com.amazonaws.dynamodb.v20111205#ResourceNotFoundException"
-        super().__init__(err, msg or "Requested resource not found")
+    def __init__(self, msg: Optional[str] = None, table_name: Optional[str] = None):
+        err = ERROR_TYPE_PREFIX + "ResourceNotFoundException"
+        default_msg = "Requested resource not found"
+        if table_name is not None:
+            default_msg += f": Table: {table_name} not found"
+        super().__init__(err, msg or default_msg)
 
 
 class TableNotFoundException(JsonRESTError):
     def __init__(self, name: str):
-        err = "com.amazonaws.dynamodb.v20111205#TableNotFoundException"
+        err = ERROR_TYPE_PREFIX + "TableNotFoundException"
         super().__init__(err, f"Table not found: {name}")
 
 
 class SourceTableNotFoundException(JsonRESTError):
     def __init__(self, source_table_name: str):
-        er = "com.amazonaws.dynamodb.v20111205#SourceTableNotFoundException"
+        er = ERROR_TYPE_PREFIX + "SourceTableNotFoundException"
         super().__init__(er, f"Source table not found: {source_table_name}")
 
 
 class BackupNotFoundException(JsonRESTError):
     def __init__(self, backup_arn: str):
-        er = "com.amazonaws.dynamodb.v20111205#BackupNotFoundException"
+        er = ERROR_TYPE_PREFIX + "BackupNotFoundException"
         super().__init__(er, f"Backup not found: {backup_arn}")
 
 
 class TableAlreadyExistsException(JsonRESTError):
     def __init__(self, target_table_name: str):
-        er = "com.amazonaws.dynamodb.v20111205#TableAlreadyExistsException"
+        er = ERROR_TYPE_PREFIX + "TableAlreadyExistsException"
         super().__init__(er, f"Table already exists: {target_table_name}")
 
 
 class ResourceInUseException(JsonRESTError):
     def __init__(self) -> None:
-        er = "com.amazonaws.dynamodb.v20111205#ResourceInUseException"
+        er = ERROR_TYPE_PREFIX + "ResourceInUseException"
         super().__init__(er, "Resource in use")
 
 
 class StreamAlreadyEnabledException(JsonRESTError):
     def __init__(self) -> None:
-        er = "com.amazonaws.dynamodb.v20111205#ResourceInUseException"
+        er = ERROR_TYPE_PREFIX + "ResourceInUseException"
         super().__init__(er, "Cannot enable stream")
 
 

moto/dynamodb/models/__init__.py

@@ -123,8 +123,10 @@ class DynamoDBBackend(BaseBackend):
         return tables, None
 
     def describe_table(self, name: str) -> Dict[str, Any]:
-        table = self.get_table(name)
-        return table.describe(base_key="Table")
+        # We can't use get_table() here, because the error message is slightly different for this operation
+        if name not in self.tables:
+            raise ResourceNotFoundException(table_name=name)
+        return self.tables[name].describe(base_key="Table")
 
     def update_table(
         self,

tests/test_dynamodb/test_dynamodb.py

@@ -66,7 +66,9 @@ def test_describe_missing_table_boto3():
         conn.describe_table(TableName="messages")
     ex.value.response["Error"]["Code"].should.equal("ResourceNotFoundException")
     ex.value.response["ResponseMetadata"]["HTTPStatusCode"].should.equal(400)
-    ex.value.response["Error"]["Message"].should.equal("Requested resource not found")
+    ex.value.response["Error"]["Message"].should.equal(
+        "Requested resource not found: Table: messages not found"
+    )
 
 
 @mock_dynamodb

tests/test_dynamodb/test_server.py

@@ -1,5 +1,6 @@
+import json
 import sure  # noqa # pylint: disable=unused-import
-
+from moto import mock_dynamodb
 import moto.server as server
 
 """
@@ -7,6 +8,7 @@ Test the different server responses
 """
 
 
+@mock_dynamodb
 def test_table_list():
     backend = server.create_backend_app("dynamodb")
     test_client = backend.test_client()
@@ -17,3 +19,18 @@ def test_table_list():
     res = test_client.get("/", headers=headers)
     res.data.should.contain(b"TableNames")
     res.headers.should.have.key("X-Amz-Crc32")
+
+    headers = {"X-Amz-Target": "DynamoDB_20120810.DescribeTable"}
+    res = test_client.post(
+        "/", headers=headers, data=json.dumps({"TableName": "test-table2"})
+    )
+    res.headers.should.have.key("X-Amzn-ErrorType").equals(
+        "com.amazonaws.dynamodb.v20120810#ResourceNotFoundException"
+    )
+    body = json.loads(res.data.decode("utf-8"))
+    body.should.equal(
+        {
+            "__type": "com.amazonaws.dynamodb.v20120810#ResourceNotFoundException",
+            "message": "Requested resource not found: Table: test-table2 not found",
+        }
+    )