From c60fb068e1138423690dd9fe500e31761d40efec Mon Sep 17 00:00:00 2001
From: Maksymilian Babarowski <maksymilian.babarowski@gmail.com>
Date: Tue, 12 Oct 2021 00:31:40 +0200
Subject: [PATCH] =?UTF-8?q?cognito-idp=20=E2=80=93=20Added=20format=20vali?=
 =?UTF-8?q?dation=20and=20implemented=20prefix=20operator=20for=20Filter?=
 =?UTF-8?q?=20param=20of=20list=5Fusers=20(#4388)?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 moto/cognitoidp/responses.py             | 14 ++++++--
 tests/test_cognitoidp/test_cognitoidp.py | 41 ++++++++++++++++++++++--
 2 files changed, 50 insertions(+), 5 deletions(-)

diff --git a/moto/cognitoidp/responses.py b/moto/cognitoidp/responses.py
index 4f5ba9846..3ad1a35b8 100644
--- a/moto/cognitoidp/responses.py
+++ b/moto/cognitoidp/responses.py
@@ -2,6 +2,7 @@ from __future__ import unicode_literals
 
 import json
 import os
+import re
 
 from moto.core.responses import BaseResponse
 from .models import cognitoidp_backends, find_region_by_value, UserStatus
@@ -332,18 +333,25 @@ class CognitoIdpResponse(BaseResponse):
                 "status": lambda u: "Enabled" if u.enabled else "Disabled",
                 "username": lambda u: u.username,
             }
-            name, value = filt.replace('"', "").replace(" ", "").split("=")
+            comparisons = {"=": lambda x, y: x == y, "^=": lambda x, y: x.startswith(y)}
+
+            match = re.match(r"([\w:]+)\s*(=|\^=)\s*\"(.*)\"", filt)
+            if match:
+                name, op, value = match.groups()
+            else:
+                raise InvalidParameterException("Error while parsing filter")
+            compare = comparisons[op]
             users = [
                 user
                 for user in users
                 if [
                     attr
                     for attr in user.attributes
-                    if attr["Name"] == name and attr["Value"] == value
+                    if attr["Name"] == name and compare(attr["Value"], value)
                 ]
                 or (
                     name in inherent_attributes
-                    and inherent_attributes[name](user) == value
+                    and compare(inherent_attributes[name](user), value)
                 )
             ]
         response = {"Users": [user.to_json(extended=True) for user in users]}
diff --git a/tests/test_cognitoidp/test_cognitoidp.py b/tests/test_cognitoidp/test_cognitoidp.py
index 18c9ac2d4..a419f0a86 100644
--- a/tests/test_cognitoidp/test_cognitoidp.py
+++ b/tests/test_cognitoidp/test_cognitoidp.py
@@ -1209,18 +1209,55 @@ def test_list_users():
         UserAttributes=[{"Name": "phone_number", "Value": "+33666666666"}],
     )
     result = conn.list_users(
-        UserPoolId=user_pool_id, Filter='phone_number="+33666666666'
+        UserPoolId=user_pool_id, Filter='phone_number="+33666666666"'
     )
     result["Users"].should.have.length_of(1)
     result["Users"][0]["Username"].should.equal(username_bis)
 
     # checking Filter with space
     result = conn.list_users(
-        UserPoolId=user_pool_id, Filter='phone_number = "+33666666666'
+        UserPoolId=user_pool_id, Filter='phone_number = "+33666666666"'
     )
     result["Users"].should.have.length_of(1)
     result["Users"][0]["Username"].should.equal(username_bis)
 
+    user0_username = "user0@example.com"
+    conn.admin_create_user(
+        UserPoolId=user_pool_id,
+        Username=user0_username,
+        UserAttributes=[{"Name": "phone_number", "Value": "+48555555555"}],
+    )
+
+    # checking Filter with prefix operator
+    result = conn.list_users(UserPoolId=user_pool_id, Filter='phone_number ^= "+48"')
+    result["Users"].should.have.length_of(1)
+    result["Users"][0]["Username"].should.equal(user0_username)
+
+    # empty value Filter should also be supported
+    result = conn.list_users(UserPoolId=user_pool_id, Filter='family_name=""')
+    result["Users"].should.have.length_of(0)
+
+
+@mock_cognitoidp
+def test_list_users_incorrect_filter():
+    conn = boto3.client("cognito-idp", "us-west-2")
+
+    user_pool_id = conn.create_user_pool(PoolName=str(uuid.uuid4()))["UserPool"]["Id"]
+
+    with pytest.raises(conn.exceptions.InvalidParameterException) as exc:
+        conn.list_users(UserPoolId=user_pool_id, Filter="username = foo")
+    _assert_filter_parsing_error(exc)
+
+    with pytest.raises(conn.exceptions.InvalidParameterException) as exc:
+        conn.list_users(UserPoolId=user_pool_id, Filter="username=")
+    _assert_filter_parsing_error(exc)
+
+
+def _assert_filter_parsing_error(exc):
+    err = exc.value.response["Error"]
+    assert err["Code"].should.equal("InvalidParameterException")
+    assert err["Message"].should.equal("Error while parsing filter")
+
 
 @mock_cognitoidp
 def test_list_users_inherent_attributes():