feat: Clean Terraform References List

samcli/hook_packages/terraform/hooks/prepare/layer_linking.py

@@ -0,0 +1,39 @@
+"""
+Use Terraform plan to link resources together
+e.g. linking layers to functions
+"""
+
+from typing import List
+
+
+def _clean_references_list(references: List[str]) -> List[str]:
+    """
+    Return a new copy of the complete references list.
+
+    e.g. given a list of references like
+    [
+        'aws_lambda_layer_version.layer1[0].arn',
+        'aws_lambda_layer_version.layer1[0]',
+        'aws_lambda_layer_version.layer1',
+    ]
+    We want only the first complete reference ('aws_lambda_layer_version.layer1[0].arn')
+
+    Parameters
+    ----------
+    references: List[str]
+        A list of reference strings
+
+    Returns
+    -------
+    List[str]
+        A copy of a cleaned list of reference strings
+    """
+    cleaned_references = []
+    copied_references = sorted(references, reverse=True)
+    if not references:
+        return []
+    cleaned_references.append(copied_references[0])
+    for i in range(1, len(copied_references)):
+        if not cleaned_references[-1].startswith(copied_references[i]):
+            cleaned_references.append(copied_references[i])
+    return cleaned_references

tests/unit/hook_packages/terraform/test_layer_linking.py

@@ -0,0 +1,67 @@
+from copy import deepcopy
+from unittest import TestCase
+
+from parameterized import parameterized
+
+from samcli.hook_packages.terraform.hooks.prepare.layer_linking import _clean_references_list
+
+
+class TestLayerLinking(TestCase):
+    @parameterized.expand(
+        [
+            ([], []),
+            (["aws_lambda_layer_version.layer1[0].arn"], ["aws_lambda_layer_version.layer1[0].arn"]),
+            (["aws_lambda_layer_version.layer1[0]"], ["aws_lambda_layer_version.layer1[0]"]),
+            (["aws_lambda_layer_version.layer1"], ["aws_lambda_layer_version.layer1"]),
+            (
+                [
+                    "aws_lambda_layer_version.layer1[0].arn",
+                    "aws_lambda_layer_version.layer1[0]",
+                    "aws_lambda_layer_version.layer1",
+                ],
+                ["aws_lambda_layer_version.layer1[0].arn"],
+            ),
+            (
+                [
+                    "aws_lambda_layer_version.layer1[0].arn",
+                    "aws_lambda_layer_version.layer1[0]",
+                    "aws_lambda_layer_version.layer1",
+                    "module.const_layer1.layer_arn",
+                    "module.const_layer1",
+                    "module.const_layer2.layer_arn",
+                    "module.const_layer2",
+                ],
+                [
+                    "module.const_layer2.layer_arn",
+                    "module.const_layer1.layer_arn",
+                    "aws_lambda_layer_version.layer1[0].arn",
+                ],
+            ),
+            (
+                [
+                    'aws_lambda_layer_version.layer1["key1"].arn',
+                    'aws_lambda_layer_version.layer1["key1"]',
+                    "aws_lambda_layer_version.layer1",
+                ],
+                ['aws_lambda_layer_version.layer1["key1"].arn'],
+            ),
+        ]
+    )
+    def test_clean_references_list(self, references, expected):
+        cleaned_references = _clean_references_list(references)
+        self.assertEqual(cleaned_references, expected)
+
+    def test_ensure_original_references_not_mutated(self):
+        references = [
+            "aws_lambda_layer_version.layer1[0].arn",
+            "aws_lambda_layer_version.layer1[0]",
+            "aws_lambda_layer_version.layer1",
+            "module.const_layer1.layer_arn",
+            "module.const_layer1",
+            "module.const_layer2.layer_arn",
+            "module.const_layer2",
+        ]
+        original_references = deepcopy(references)
+        cleaned_references_list = _clean_references_list(references)
+        self.assertEqual(references, original_references)
+        self.assertNotEqual(references, cleaned_references_list)