Add update_if_exist option to add_output

With !89+ assets export an output for the S3 URI. It
doesn't work for PyFunctionAssets if reused multiple times as
`add_output` doesn't check if the output already exists.

With this change, the function can override the already
existing output to avoid the error

Author: adanaja

src/e3/aws/troposphere/__init__.py

@@ -128,7 +128,8 @@ def resources(self, stack: Stack) -> list[AWSObject | Construct]:
                 Description=f"S3 URI for the Asset {self.name}",
                 Export=Export(name=self.s3_uri_output_name),
                 Value=f"s3://{stack.s3_bucket}/{stack.s3_assets_key}{self.s3_key}",
-            )
+            ),
+            update_if_exist=True,
         )
         return []
 
@@ -309,12 +310,23 @@ def add_parameter(self, parameter: Parameter | list[Parameter]) -> None:
             else:
                 self.template.add_parameter(param)
 
-    def add_output(self, output: Output | list[Output]) -> None:
+    def add_output(
+        self, output: Output | list[Output], update_if_exist: bool = False
+    ) -> None:
         """Add outputs to stack template.
 
         :param output: output to add to the template
+        :param update_if_exist: update the output if already exists, avoiding
+            the duplicate key exception
         """
-        self.template.add_output(output)
+        if not isinstance(output, list):
+            output = [output]
+
+        for out in output:
+            if update_if_exist and out.title in self.template.outputs:
+                self.template.outputs[out.title] = out
+            else:
+                self.template.add_output(out)
 
     def add_condition(self, condition_name: str, condition: ConditionFunction) -> None:
         """Add condition to stack template.

tests/tests_e3_aws/troposphere/stack/stack_test.py

@@ -2,7 +2,7 @@
 
 import json
 from pathlib import Path
-
+import pytest
 from troposphere import Parameter, Output, Export
 
 from e3.aws.troposphere.s3.bucket import Bucket
@@ -85,6 +85,30 @@ def test_add_outputs() -> None:
     assert stack.export()["Resources"] == expected_template
 
 
+def test_update_output() -> None:
+    """Test updating an already existing output."""
+    o = Output("Output", Description="My output", Value=Export(name="Output"))
+    stack = Stack("test-stack", "this is a test stack")
+    stack.add_output(o)
+
+    # This one should fail because of the duplicate key
+    with pytest.raises(match='duplicate key "Output" detected'):
+        stack.add_output(o)
+
+    # This one should update the output
+    o.Description = "Updated output"
+    stack.add_output(o, update_if_exist=True)
+
+    assert stack.export()["Outputs"] == {
+        "Output": {
+            "Description": "Updated output",
+            "Value": {
+                "Name": "Output",
+            },
+        },
+    }
+
+
 def test_extend() -> None:
     """Test adding multiple construct and retrieving an AWSObject from a stack."""
     stack = Stack("test-stack", "this is a test stack")