fix: Decouple samtranslator.models and *.intrinsics and add import tests

samtranslator/internal/intrinsics.py

@@ -0,0 +1,23 @@
+from typing import Any, Dict, Optional, Union
+
+from samtranslator.intrinsics.resolver import IntrinsicsResolver
+from samtranslator.model.exceptions import InvalidResourceException
+
+
+def resolve_string_parameter_in_resource(
+    logical_id: str,
+    intrinsics_resolver: IntrinsicsResolver,
+    parameter_value: Optional[Union[str, Dict[str, Any]]],
+    parameter_name: str,
+) -> Optional[Union[str, Dict[str, Any]]]:
+    """Try to resolve values in a resource from template parameters."""
+    if not parameter_value:
+        return parameter_value
+    value = intrinsics_resolver.resolve_parameter_refs(parameter_value)
+
+    if not isinstance(value, str) and not isinstance(value, dict):
+        raise InvalidResourceException(
+            logical_id,
+            "Could not resolve parameter for '{}' or parameter is not a String.".format(parameter_name),
+        )
+    return value

samtranslator/model/__init__.py

@@ -8,7 +8,6 @@
 from pydantic import BaseModel
 from pydantic.error_wrappers import ValidationError
 
-from samtranslator.intrinsics.resolver import IntrinsicsResolver
 from samtranslator.model.exceptions import (
     ExpectedType,
     InvalidResourceException,
@@ -544,23 +543,6 @@ def _check_tag(self, reserved_tag_name, tags):  # type: ignore[no-untyped-def]
                 "input.",
             )
 
-    def _resolve_string_parameter(
-        self,
-        intrinsics_resolver: IntrinsicsResolver,
-        parameter_value: Optional[Union[str, Dict[str, Any]]],
-        parameter_name: str,
-    ) -> Optional[Union[str, Dict[str, Any]]]:
-        if not parameter_value:
-            return parameter_value
-        value = intrinsics_resolver.resolve_parameter_refs(parameter_value)
-
-        if not isinstance(value, str) and not isinstance(value, dict):
-            raise InvalidResourceException(
-                self.logical_id,
-                "Could not resolve parameter for '{}' or parameter is not a String.".format(parameter_name),
-            )
-        return value
-
 
 class ResourceTypeResolver:
     """ResourceTypeResolver maps Resource Types to Resource classes, e.g. AWS::Serverless::Function to

samtranslator/model/sam_resources.py

@@ -86,6 +86,7 @@
 from .packagetype import IMAGE, ZIP
 from .s3_utils.uri_parser import construct_image_code_object, construct_s3_location_object
 from .tags.resource_tagging import get_tag_list
+from ..internal.intrinsics import resolve_string_parameter_in_resource
 
 _CONDITION_CHAR_LIMIT = 255
 
@@ -1571,11 +1572,17 @@ def _construct_lambda_layer(self, intrinsics_resolver: IntrinsicsResolver) -> La
         :rtype: list
         """
         # Resolve intrinsics if applicable:
-        self.LayerName = self._resolve_string_parameter(intrinsics_resolver, self.LayerName, "LayerName")
-        self.LicenseInfo = self._resolve_string_parameter(intrinsics_resolver, self.LicenseInfo, "LicenseInfo")
-        self.Description = self._resolve_string_parameter(intrinsics_resolver, self.Description, "Description")
-        self.RetentionPolicy = self._resolve_string_parameter(
-            intrinsics_resolver, self.RetentionPolicy, "RetentionPolicy"
+        self.LayerName = resolve_string_parameter_in_resource(
+            self.logical_id, intrinsics_resolver, self.LayerName, "LayerName"
+        )
+        self.LicenseInfo = resolve_string_parameter_in_resource(
+            self.logical_id, intrinsics_resolver, self.LicenseInfo, "LicenseInfo"
+        )
+        self.Description = resolve_string_parameter_in_resource(
+            self.logical_id, intrinsics_resolver, self.Description, "Description"
+        )
+        self.RetentionPolicy = resolve_string_parameter_in_resource(
+            self.logical_id, intrinsics_resolver, self.RetentionPolicy, "RetentionPolicy"
         )
 
         # If nothing defined, this will be set to Retain