New rule W0510 to validate transform order

src/cfnlint/rules/transforms/LanguageExtensionsBeforeSAM.py

@@ -0,0 +1,39 @@
+"""
+Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+SPDX-License-Identifier: MIT-0
+"""
+
+from cfnlint.rules import CloudFormationLintRule, RuleMatch
+
+
+class LanguageExtensionsBeforeSAM(CloudFormationLintRule):
+    """Check if Serverless Resources exist without the Serverless Transform"""
+
+    id = "W0510"
+    shortdesc = "Put LanguageExtensions before SAM transform"
+    description = (
+        "If using language extensions with SAM, you should add AWS::LanguageExtensions "
+        "before the serverless transform (that is, before AWS::Serverless-2016-10-31)"
+    )
+    source_url = "https://docs.aws.amazon.com/serverless-application-model/latest/developerguide/sam-specification-template-anatomy.html"
+    tags = ["transforms"]
+
+    def match(self, cfn):
+        matches = []
+
+        if isinstance(cfn.transform_pre["Transform"], list):
+            flag = False
+            for i, transform in enumerate(cfn.transform_pre["Transform"]):
+                if transform == "AWS::Serverless-2016-10-31":
+                    flag = True
+                if transform == "AWS::LanguageExtensions" and flag:
+                    matches.append(
+                        RuleMatch(
+                            ["Transform", i],
+                            (
+                                "Place 'AWS::LanguageExtensions' before "
+                                "'AWS::Serverless-2016-10-31'"
+                            ),
+                        )
+                    )
+        return matches

test/fixtures/templates/bad/transforms/language_extensions_with_sam.yaml

@@ -0,0 +1,10 @@
+Transform:
+ - AWS::Serverless-2016-10-31
+ - AWS::LanguageExtensions
+Resources:
+  MyFunction:
+    Type: AWS::Serverless::Function
+    Properties:
+      Handler: index.handler
+      Runtime: nodejs20.x
+      CodeUri: 's3://testBucket/mySourceCode.zip'

test/fixtures/templates/good/transforms/language_extensions_with_other.yaml

@@ -0,0 +1,6 @@
+Transform:
+ - MyOtherTransform
+ - AWS::LanguageExtensions
+Resources:
+  Bucket:
+    Type: AWS::S3::Bucket

test/fixtures/templates/good/transforms/language_extensions_with_sam.yaml

@@ -0,0 +1,10 @@
+Transform:
+ - AWS::LanguageExtensions
+ - AWS::Serverless-2016-10-31
+Resources:
+  MyFunction:
+    Type: AWS::Serverless::Function
+    Properties:
+      Handler: index.handler
+      Runtime: nodejs20.x
+      CodeUri: 's3://testBucket/mySourceCode.zip'

test/fixtures/templates/good/transforms/string_transform.yaml

@@ -0,0 +1,8 @@
+Transform: AWS::Serverless-2016-10-31
+Resources:
+  MyFunction:
+    Type: AWS::Serverless::Function
+    Properties:
+      Handler: index.handler
+      Runtime: nodejs20.x
+      CodeUri: 's3://testBucket/mySourceCode.zip'

test/unit/rules/transforms/test_language_extensions_before_sam.py

@@ -0,0 +1,35 @@
+"""
+Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+SPDX-License-Identifier: MIT-0
+"""
+
+from test.unit.rules import BaseRuleTestCase
+
+from cfnlint.rules.transforms.LanguageExtensionsBeforeSAM import (
+    LanguageExtensionsBeforeSAM,  # pylint: disable=E0401
+)
+
+
+class TestLanguageExtensionsBeforeSAM(BaseRuleTestCase):
+    """Test template limit size"""
+
+    def setUp(self):
+        """Setup"""
+        super(TestLanguageExtensionsBeforeSAM, self).setUp()
+        self.collection.register(LanguageExtensionsBeforeSAM())
+        self.success_templates = [
+            "test/fixtures/templates/good/transforms/language_extensions_with_sam.yaml",
+            "test/fixtures/templates/good/transforms/string_transform.yaml",
+            "test/fixtures/templates/good/transforms/language_extensions_with_other.yaml",
+        ]
+
+    def test_file_positive(self):
+        """Test Positive"""
+        self.helper_file_positive()
+
+    def test_file_negative(self):
+        """Test failure"""
+        self.helper_file_negative(
+            "test/fixtures/templates/bad/transforms/language_extensions_with_sam.yaml",
+            1,
+        )