diff --git a/tests/domain/cloud/test_aws_csp.py b/tests/domain/cloud/test_aws_csp.py
index c71e3fa0..4a1ffd74 100644
--- a/tests/domain/cloud/test_aws_csp.py
+++ b/tests/domain/cloud/test_aws_csp.py
@@ -48,3 +48,18 @@ def test_create_atat_admin_when_user_already_exists(mock_aws):
 
     iam_client = mock_aws.boto3.client("iam")
     iam_client.get_user.assert_any_call(UserName="atat")
+
+
+def test_create_environment_baseline_succeeds(mock_aws):
+    baseline_info = mock_aws.create_environment_baseline(
+        AUTH_CREDENTIALS, "csp_environment_id"
+    )
+    assert {"policies": [{"BillingReadOnly": "policy-arn"}]} == baseline_info
+
+
+@pytest.mark.mock_boto3({"iam.create_policy.already_exists": True})
+def test_create_environment_baseline_when_policy_already_exists(mock_aws):
+    baseline_info = mock_aws.create_environment_baseline(
+        AUTH_CREDENTIALS, "csp_environment_id"
+    )
+    assert "policies" in baseline_info
diff --git a/tests/mock_boto3.py b/tests/mock_boto3.py
index 4926a100..dbab9fe6 100644
--- a/tests/mock_boto3.py
+++ b/tests/mock_boto3.py
@@ -54,6 +54,12 @@ def mock_boto_organizations(_config=None, **kwargs):
 
 def mock_boto_iam(_config=None, **kwargs):
     user_already_exists = _config.get("iam.create_user.already_exists", False)
+    policy_already_exists = _config.get("iam.create_policy.already_exists", False)
+
+    def _raise_entity_already_exists(**kwargs):
+        raise real_iam_client.exceptions.EntityAlreadyExistsException(
+            {"Error": {}}, "operation-name"
+        )
 
     import boto3
 
@@ -66,13 +72,7 @@ def mock_boto_iam(_config=None, **kwargs):
     mock.put_user_policy = Mock(return_value={"ResponseMetadata": {}})
 
     if user_already_exists:
-
-        def _raise(**kwargs):
-            raise real_iam_client.exceptions.EntityAlreadyExistsException(
-                {"Error": {}}, "operation-name"
-            )
-
-        mock.create_user = Mock(side_effect=_raise)
+        mock.create_user = Mock(side_effect=_raise_entity_already_exists)
     else:
         mock.create_user = Mock(
             return_value={
@@ -99,6 +99,11 @@ def mock_boto_iam(_config=None, **kwargs):
         }
     )
 
+    if policy_already_exists:
+        mock.create_policy = Mock(side_effect=_raise_entity_already_exists)
+    else:
+        mock.create_policy = Mock(return_value={"Policy": {"Arn": "policy-arn"}})
+
     return mock