diff --git a/rope/refactor/importutils/importinfo.py b/rope/refactor/importutils/importinfo.py
index 640200c4..451a387e 100644
--- a/rope/refactor/importutils/importinfo.py
+++ b/rope/refactor/importutils/importinfo.py
@@ -1,4 +1,5 @@
-from typing import List, Tuple
+from abc import abstractmethod, ABC
+from typing import List, Tuple, Optional, Protocol
 
 
 class ImportStatement:
@@ -64,9 +65,11 @@ def accept(self, visitor):
         return visitor.dispatch(self)
 
 
-class ImportInfo:
-    def get_imported_primaries(self, context):
-        pass
+class ImportInfo(ABC):
+    names_and_aliases: List[Tuple[str, Optional[str]]]
+
+    @abstractmethod
+    def get_imported_primaries(self, context) -> List[str]: ...
 
     def get_imported_names(self, context):
         return [
@@ -76,8 +79,8 @@ def get_imported_names(self, context):
     def __repr__(self):
         return f'<{self.__class__.__name__} "{self.get_import_statement()}">'
 
-    def get_import_statement(self):
-        pass
+    @abstractmethod
+    def get_import_statement(self) -> str: ...
 
     def is_empty(self):
         pass
@@ -108,10 +111,13 @@ def get_empty_import():
 
 
 class NormalImport(ImportInfo):
-    def __init__(self, names_and_aliases):
+    def __init__(
+        self,
+        names_and_aliases: List[Tuple[str, Optional[str]]],
+    ) -> None:
         self.names_and_aliases = names_and_aliases
 
-    def get_imported_primaries(self, context):
+    def get_imported_primaries(self, context) -> List[str]:
         result = []
         for name, alias in self.names_and_aliases:
             if alias:
@@ -120,7 +126,7 @@ def get_imported_primaries(self, context):
                 result.append(name)
         return result
 
-    def get_import_statement(self):
+    def get_import_statement(self) -> str:
         result = "import "
         for name, alias in self.names_and_aliases:
             result += name
@@ -134,12 +140,20 @@ def is_empty(self):
 
 
 class FromImport(ImportInfo):
-    def __init__(self, module_name, level, names_and_aliases):
+    module_name: str
+    level: int
+
+    def __init__(
+        self,
+        module_name: str,
+        level: int,
+        names_and_aliases: List[Tuple[str, Optional[str]]],
+    ):
         self.module_name = module_name
         self.level = level
         self.names_and_aliases = names_and_aliases
 
-    def get_imported_primaries(self, context):
+    def get_imported_primaries(self, context) -> List[str]:
         if self.names_and_aliases[0][0] == "*":
             module = self.get_imported_module(context)
             return [name for name in module if not name.startswith("_")]
@@ -176,7 +190,7 @@ def get_imported_module(self, context):
                 self.module_name, context.folder, self.level
             )
 
-    def get_import_statement(self):
+    def get_import_statement(self) -> str:
         result = "from " + "." * self.level + self.module_name + " import "
         for name, alias in self.names_and_aliases:
             result += name
@@ -193,14 +207,17 @@ def is_star_import(self):
 
 
 class EmptyImport(ImportInfo):
-    names_and_aliases: List[Tuple[str, str]] = []
+    names_and_aliases = []
 
     def is_empty(self):
         return True
 
-    def get_imported_primaries(self, context):
+    def get_imported_primaries(self, context) -> List[str]:
         return []
 
+    def get_import_statement(self) -> str:
+        raise NotImplementedError()
+
 
 class ImportContext:
     def __init__(self, project, folder):