Raise ``AttributeInferenceError`` when ``getattr()`` receives an empty name

If `Module.getattr` received an empty string (as a result of inference for example),
`astroid` would have returned the same Module again, which leads to false positives
in pylint, since the expected output was of a different type.

Rather than allowing empty names to pass through `getattr()`, we simply raise
an error earlier.

Close PyCQA/pylint#2991

3 files changed, 32 insertions, 0 deletions

diff --git a/ChangeLog b/ChangeLog
index 2e712db2..7485f123 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -10,6 +10,10 @@ Release Date: TBA
 
   Close PyCQA/pylint#3417
 
+* Raise ``AttributeInferenceError`` when ``getattr()`` receives an empty name
+
+  Close PyCQA/pylint#2991
+
 * ``NodeNG.bool_value()`` gained an optional ``context`` parameter
 
   We need to pass an inference context downstream when inferring the boolean
diff --git a/astroid/scoped_nodes.py b/astroid/scoped_nodes.py
index 922f4c58..8070f17d 100644
--- a/astroid/scoped_nodes.py
+++ b/astroid/scoped_nodes.py
@@ -527,6 +527,11 @@ class Module(LocalsDictNodeNG):
         return "Module"
 
     def getattr(self, name, context=None, ignore_locals=False):
+        if not name:
+            raise exceptions.AttributeInferenceError(
+                target=self, attribute=name, context=context
+            )
+
         result = []
         name_in_locals = name in self.locals
 
@@ -1551,6 +1556,10 @@ class FunctionDef(mixins.MultiLineBlockMixin, node_classes.Statement, Lambda):
         """this method doesn't look in the instance_attrs dictionary since it's
         done by an Instance proxy at inference time.
         """
+        if not name:
+            raise exceptions.AttributeInferenceError(
+                target=self, attribute=name, context=context
+            )
         if name in self.instance_attrs:
             return self.instance_attrs[name]
         if name in self.special_attributes:
@@ -2406,6 +2415,11 @@ class ClassDef(mixins.FilterStmtsMixin, LocalsDictNodeNG, node_classes.Statement
 
         :raises AttributeInferenceError: If the attribute cannot be inferred.
         """
+        if not name:
+            raise exceptions.AttributeInferenceError(
+                target=self, attribute=name, context=context
+            )
+
         values = self.locals.get(name, [])
         if name in self.special_attributes and class_context and not values:
             result = [self.special_attributes.lookup(name)]
diff --git a/tests/unittest_inference.py b/tests/unittest_inference.py
index 49ff6cdc..7f86de4d 100644
--- a/tests/unittest_inference.py
+++ b/tests/unittest_inference.py
@@ -5729,5 +5729,19 @@ def test_inferring_properties_multiple_time_does_not_mutate_locals_multiple_time
     assert len(a_locals) == 2
 
 
+def test_getattr_fails_on_empty_values():
+    code = """
+    import collections
+    collections
+    """
+    node = extract_node(code)
+    inferred = next(node.infer())
+    with pytest.raises(exceptions.InferenceError):
+        next(inferred.igetattr(""))
+
+    with pytest.raises(exceptions.AttributeInferenceError):
+        inferred.getattr("")
+
+
 if __name__ == "__main__":
     unittest.main()