fawltydeps_suggestions.patch

diff --git a/fawltydeps/check.py b/fawltydeps/check.py
index f48139d..8c67173 100644
--- a/fawltydeps/check.py
+++ b/fawltydeps/check.py
@@ -2,9 +2,13 @@
 
 import logging
 from itertools import groupby
-from typing import Dict, List
+from typing import Dict, List, Iterable
 
-from fawltydeps.packages import Package
+from fawltydeps.packages import (
+    BasePackageResolver,
+    Package,
+    resolve_dependencies,
+)
 from fawltydeps.settings import Settings
 from fawltydeps.types import (
     DeclaredDependency,
@@ -15,10 +19,16 @@ from fawltydeps.types import (
 
 logger = logging.getLogger(__name__)
 
+def _candidates(import_name: str, known_packages: Iterable[BasePackageResolver]) -> List[Package]:
+    for resolver in known_packages:
+        for package in resolver.all_packages():
+            if import_name in package.import_names:
+                yield package
 
 def calculate_undeclared(
     imports: List[ParsedImport],
     resolved_deps: Dict[str, Package],
+    known_packages: Iterable[BasePackageResolver],
     settings: Settings,
 ) -> List[UndeclaredDependency]:
     """Calculate which imports are not covered by declared dependencies.
@@ -35,7 +45,7 @@ def calculate_undeclared(
     ]
     undeclared.sort(key=lambda i: i.name)  # groupby requires pre-sorting
     return [
-        UndeclaredDependency(name, [i.source for i in imports])
+        UndeclaredDependency(name, [i.source for i in imports], list(_candidates(name, known_packages)))
         for name, imports in groupby(undeclared, key=lambda i: i.name)
     ]
 
diff --git a/fawltydeps/cli_parser.py b/fawltydeps/cli_parser.py
index 5cf2f10..8441aa0 100644
--- a/fawltydeps/cli_parser.py
+++ b/fawltydeps/cli_parser.py
@@ -223,6 +223,11 @@ def populate_parser_paths_options(parser: argparse._ActionsContainer) -> None:
             " defined by the user."
         ),
     )
+    parser.add_argument(
+        "--base_path",
+        type=Path,
+        metavar="BASE_PATH",
+    )
 
 
 def populate_parser_configuration(parser: argparse._ActionsContainer) -> None:
diff --git a/fawltydeps/dir_traversal.py b/fawltydeps/dir_traversal.py
index 1a8ffe8..77e3e88 100644
--- a/fawltydeps/dir_traversal.py
+++ b/fawltydeps/dir_traversal.py
@@ -129,7 +129,9 @@ class DirectoryTraversal(Generic[T]):
           instance, it will _not_ be re-traversed.
         """
         if not dir_path.is_dir():
-            raise NotADirectoryError(dir_path)
+            #raise NotADirectoryError(dir_path)
+            return
+            dir_path = Path()
         dir_id = DirId.from_path(dir_path)
         self.to_traverse[dir_path] = dir_id
         self.attached.setdefault(dir_id, []).extend(attach_data)
diff --git a/fawltydeps/main.py b/fawltydeps/main.py
index fb467d6..99cf21f 100644
--- a/fawltydeps/main.py
+++ b/fawltydeps/main.py
@@ -135,27 +135,32 @@ class Analysis:
             )
         )
 
+    @property
+    @calculated_once
+    def resolvers(self) -> Iterable[BasePackageResolver]:
+        pyenv_srcs = {src for src in self.sources if isinstance(src, PyEnvSource)}
+        return list(setup_resolvers(
+            custom_mapping_files=self.settings.custom_mapping_file,
+            custom_mapping=self.settings.custom_mapping,
+            pyenv_srcs=pyenv_srcs,
+            use_current_env=True,
+            install_deps=self.settings.install_deps,
+        ))
+
     @property
     @calculated_once
     def resolved_deps(self) -> Dict[str, Package]:
         """The resolved mapping of dependency names to provided import names."""
-        pyenv_srcs = {src for src in self.sources if isinstance(src, PyEnvSource)}
         return resolve_dependencies(
             (dep.name for dep in self.declared_deps),
-            setup_resolvers(
-                custom_mapping_files=self.settings.custom_mapping_file,
-                custom_mapping=self.settings.custom_mapping,
-                pyenv_srcs=pyenv_srcs,
-                use_current_env=True,
-                install_deps=self.settings.install_deps,
-            ),
+            self.resolvers,
         )
 
     @property
     @calculated_once
     def undeclared_deps(self) -> List[UndeclaredDependency]:
         """The import statements for which no declared dependency is found."""
-        return calculate_undeclared(self.imports, self.resolved_deps, self.settings)
+        return calculate_undeclared(self.imports, self.resolved_deps, self.resolvers, self.settings)
 
     @property
     @calculated_once
diff --git a/fawltydeps/packages.py b/fawltydeps/packages.py
index efb0e72..26b7605 100644
--- a/fawltydeps/packages.py
+++ b/fawltydeps/packages.py
@@ -116,6 +116,9 @@ class BasePackageResolver(ABC):
         """
         raise NotImplementedError
 
+    def all_packages(self) -> Iterable[Package]:
+        return []
+
 
 def accumulate_mappings(
     resolved_with: Type[BasePackageResolver],
@@ -205,6 +208,8 @@ class UserDefinedMapping(BasePackageResolver):
             if Package.normalize_name(name) in self.packages
         }
 
+    def all_packages(self) -> Iterable[Package]:
+        return self.packages.values()
 
 class InstalledPackageResolver(BasePackageResolver):
     """Lookup imports exposed by packages installed in a Python environment."""
@@ -282,6 +287,9 @@ class InstalledPackageResolver(BasePackageResolver):
             if Package.normalize_name(name) in self.packages
         }
 
+    def all_packages(self) -> Iterable[Package]:
+        return self.packages.values()
+
 
 class SysPathPackageResolver(InstalledPackageResolver):
     """Lookup imports exposed by packages installed in sys.path."""
@@ -639,7 +647,9 @@ def validate_pyenv_source(path: Path) -> Optional[Set[PyEnvSource]]:
     - Raise UnparseablePathError if the given path is not a directory.
     """
     if not path.is_dir():
-        raise UnparseablePathError(ctx="Not a directory!", path=path)
+        #raise UnparseablePathError(ctx="Not a directory!", path=path)
+        # maybe just a warning ?
+        return None
     try:
         return pyenv_sources(path)
     except ValueError:
diff --git a/fawltydeps/settings.py b/fawltydeps/settings.py
index dbf1467..8327ac8 100644
--- a/fawltydeps/settings.py
+++ b/fawltydeps/settings.py
@@ -156,6 +156,7 @@ class Settings(BaseSettings):
     """
 
     actions: Set[Action] = {Action.REPORT_UNDECLARED, Action.REPORT_UNUSED}
+    base_path: Optional[Path] = None
     output_format: OutputFormat = OutputFormat.HUMAN_SUMMARY
     code: Set[PathOrSpecial] = {Path()}
     deps: Set[Path] = {Path()}
diff --git a/fawltydeps/traverse_project.py b/fawltydeps/traverse_project.py
index e48406d..90fb558 100644
--- a/fawltydeps/traverse_project.py
+++ b/fawltydeps/traverse_project.py
@@ -102,7 +102,7 @@ def find_sources(  # noqa: C901, PLR0912, PLR0915
 
     for path_or_special in settings.code if CodeSource in source_types else []:
         # exceptions raised by validate_code_source() are propagated here
-        validated: Optional[Source] = validate_code_source(path_or_special)
+        validated: Optional[Source] = validate_code_source(path_or_special, settings.base_path)
         if validated is not None:  # parse-able file given directly
             logger.debug(f"find_sources() Found {validated}")
             yield validated
diff --git a/fawltydeps/types.py b/fawltydeps/types.py
index bd3d909..f429826 100644
--- a/fawltydeps/types.py
+++ b/fawltydeps/types.py
@@ -286,6 +286,7 @@ class UndeclaredDependency:
 
     name: str
     references: List[Location]
+    candidates: List[Package]
 
     def render(self, *, include_references: bool) -> str:
         """Return a human-readable string representation.
diff --git a/fawltydeps/utils.py b/fawltydeps/utils.py
index 4639247..82ec15f 100644
--- a/fawltydeps/utils.py
+++ b/fawltydeps/utils.py
@@ -27,9 +27,10 @@ def version() -> str:
 
 def dirs_between(parent: Path, child: Path) -> Iterator[Path]:
     """Yield directories between 'parent' and 'child', inclusive."""
-    yield child
-    if child != parent:
-        yield from dirs_between(parent, child.parent)
+    return [ p for p in child.parents if str(p).startswith(str(parent))] or [parent]
+    #yield child
+    #if child != parent:
+    #    yield from dirs_between(parent, child.parent)
 
 
 def hide_dataclass_fields(instance: object, *field_names: str) -> None: