Allow to ignore a list of RegEx expressions in layer contract

src/importlinter/contracts/layers.py

@@ -51,6 +51,7 @@ class LayersContract(Contract):
     containers = fields.ListField(subfield=fields.StringField())
     layers = fields.ListField(subfield=LayerField())
     ignore_imports = fields.ListField(subfield=fields.DirectImportField(), required=False)
+    ignore = fields.ListField(subfield=fields.RegExField(), required=False)
 
     def check(self, graph: ImportGraph) -> ContractCheck:
         is_kept = True
@@ -72,11 +73,12 @@ def check(self, graph: ImportGraph) -> ContractCheck:
                     if lower_layer_package.name not in graph.modules:
                         continue
 
-                    descendants = set(
-                        map(Module, graph.find_descendants(higher_layer_package.name)))
+                    descendants = set(map(Module, graph.find_descendants(higher_layer_package.name)))
+                    descendants = self._exclude_ignored(descendants) if self.ignore else descendants
                     higher_layer_modules = {higher_layer_package} | descendants
 
                     descendants = set(map(Module, graph.find_descendants(lower_layer_package.name)))
+                    descendants = self._exclude_ignored(descendants) if self.ignore else descendants
                     lower_layer_modules = {lower_layer_package} | descendants
 
                     layer_chain_data = {
@@ -138,6 +140,9 @@ def render_broken_contract(self, check: ContractCheck) -> None:
 
             output.new_line()
 
+    def _exclude_ignored(self, descendants):
+        return {d for d in descendants if not any(lambda reg: reg.match(d.name), self.ignore)}
+
     def _validate_containers(self) -> None:
         root_package_name = self.session_options['root_package']
         for container in self.containers:  # type: ignore

src/importlinter/domain/fields.py

@@ -1,4 +1,4 @@
-from typing import List, Union, Any
+from typing import List, Union, Any, Pattern
 import re
 import abc
 
@@ -40,6 +40,16 @@ def parse(self, raw_data: Union[str, List]) -> str:
         return str(raw_data)
 
 
+class RegExField(Field):
+    """
+    A field for single regex expressions.
+    """
+    def parse(self, raw_data: Union[str, List]) -> Pattern[str]:
+        if isinstance(raw_data, list):
+            raise ValidationError('Expected a single value, got multiple values.')
+        return re.compile(str(raw_data))
+
+
 class ListField(Field):
     """
     A field for multiple values of any type.