Fix:update rule (#3734)

* Fix:SQS-message retention period consideration

* Fix:SQS-message retention period consideration

* Fix:SQS-message retention period consideration

* Added comments &linting

* Fixed tests

* Fix:update rule

* Linting and comments

moto/events/models.py

@@ -672,10 +672,22 @@ class EventsBackend(BaseBackend):
 
         return return_obj
 
+    def update_rule(self, rule, **kwargs):
+        rule.event_pattern = kwargs.get("EventPattern") or rule.event_pattern
+        rule.schedule_exp = kwargs.get("ScheduleExpression") or rule.schedule_exp
+        rule.state = kwargs.get("State") or rule.state
+        rule.description = kwargs.get("Description") or rule.description
+        rule.role_arn = kwargs.get("RoleArn") or rule.role_arn
+        rule.event_bus_name = kwargs.get("EventBusName") or rule.event_bus_name
+
     def put_rule(self, name, **kwargs):
-        new_rule = Rule(name, self.region_name, **kwargs)
-        self.rules[new_rule.name] = new_rule
-        self.rules_order.append(new_rule.name)
+        if name in self.rules:
+            self.update_rule(self.rules[name], **kwargs)
+            new_rule = self.rules[name]
+        else:
+            new_rule = Rule(name, self.region_name, **kwargs)
+            self.rules[new_rule.name] = new_rule
+            self.rules_order.append(new_rule.name)
         return new_rule
 
     def put_targets(self, name, targets):

tests/test_events/test_events.py

@@ -208,6 +208,37 @@ def test_remove_targets():
     assert targets_before - 1 == targets_after
 
 
+@mock_events
+def test_update_rule_with_targets():
+    client = boto3.client("events", "us-west-2")
+    client.put_rule(
+        Name="test1", ScheduleExpression="rate(5 minutes)", EventPattern="",
+    )
+
+    client.put_targets(
+        Rule="test1",
+        Targets=[
+            {
+                "Id": "test-target-1",
+                "Arn": "arn:aws:lambda:us-west-2:111111111111:function:test-function-1",
+            }
+        ],
+    )
+
+    targets = client.list_targets_by_rule(Rule="test1")["Targets"]
+    targets_before = len(targets)
+    assert targets_before == 1
+
+    client.put_rule(
+        Name="test1", ScheduleExpression="rate(1 minute)", EventPattern="",
+    )
+
+    targets = client.list_targets_by_rule(Rule="test1")["Targets"]
+
+    assert len(targets) == 1
+    assert targets[0].get("Id") == "test-target-1"
+
+
 @mock_events
 def test_remove_targets_errors():
     client = boto3.client("events", "us-east-1")