Extend dedup to handle star+explicit clashes and add edge case tests

Extend _deduplicate_star_suggestions() to also consider explicit (non-star)
imports in the seen set, preventing star imports from suggesting names that
already have an explicit import. This fixes duplicate output like:
  from json import JSONEncoder  (from star expansion)
  from json import JSONEncoder  (from explicit import)

Add two new edge case test cases:
- partial_overlap_star_imports: reverse order where each star import has
  both shared and unique names, verifying unique names are preserved
- star_import_with_explicit: star import + explicit import of same name,
  verifying star doesn't duplicate the explicit import

Update existing star_imports and 2 test expectations to reflect the fix
(json star import no longer suggests JSONEncoder when explicit import exists).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: hakancelikdev

src/unimport/analyzers/main.py

@@ -55,16 +55,19 @@ def skip_file(self) -> bool:
 
     @staticmethod
     def _deduplicate_star_suggestions() -> None:
-        """Remove duplicate suggestions across star imports.
+        """Remove duplicate suggestions across star and explicit imports.
 
-        When multiple star imports export the same name, the last one wins
-        (matching Python's shadowing semantics).
+        When multiple imports provide the same name, the last one wins
+        (matching Python's shadowing semantics). Explicit imports also
+        claim their name so star imports don't produce duplicates.
         """
         seen: set[str] = set()
         for imp in reversed(Import.imports):
             if isinstance(imp, ImportFrom) and imp.star:
                 imp.suggestions = [s for s in imp.suggestions if s not in seen]
                 seen.update(imp.suggestions)
+            else:
+                seen.add(imp.name)
 
     @staticmethod
     def clear():

tests/cases/analyzer/star_import/2.py

@@ -96,7 +96,7 @@
         name="json",
         package="json",
         star=True,
-        suggestions=["JSONEncoder"],
+        suggestions=[],
     ),
     ImportFrom(
         lineno=14,
@@ -114,7 +114,7 @@
         name="json",
         package="json",
         star=True,
-        suggestions=["JSONEncoder"],
+        suggestions=[],
     ),
     ImportFrom(
         lineno=1,

tests/cases/analyzer/star_import/partial_overlap_star_imports.py

@@ -0,0 +1,51 @@
+from typing import Union
+
+from unimport.statement import Import, ImportFrom, Name
+
+__all__ = ["NAMES", "IMPORTS", "UNUSED_IMPORTS"]
+
+
+NAMES: list[Name] = [
+    Name(lineno=4, name="print", is_all=False),
+    Name(lineno=4, name="Counter", is_all=False),
+    Name(lineno=5, name="print", is_all=False),
+    Name(lineno=5, name="defaultdict", is_all=False),
+    Name(lineno=6, name="print", is_all=False),
+    Name(lineno=6, name="deque", is_all=False),
+]
+IMPORTS: list[Union[Import, ImportFrom]] = [
+    ImportFrom(
+        lineno=1,
+        column=1,
+        name="collections",
+        package="collections",
+        star=True,
+        suggestions=["Counter"],
+    ),
+    ImportFrom(
+        lineno=2,
+        column=1,
+        name="_collections",
+        package="_collections",
+        star=True,
+        suggestions=["defaultdict", "deque"],
+    ),
+]
+UNUSED_IMPORTS: list[Union[Import, ImportFrom]] = [
+    ImportFrom(
+        lineno=2,
+        column=1,
+        name="_collections",
+        package="_collections",
+        star=True,
+        suggestions=["defaultdict", "deque"],
+    ),
+    ImportFrom(
+        lineno=1,
+        column=1,
+        name="collections",
+        package="collections",
+        star=True,
+        suggestions=["Counter"],
+    ),
+]

tests/cases/analyzer/star_import/star_import_with_explicit.py

@@ -0,0 +1,39 @@
+from typing import Union
+
+from unimport.statement import Import, ImportFrom, Name
+
+__all__ = ["NAMES", "IMPORTS", "UNUSED_IMPORTS"]
+
+
+NAMES: list[Name] = [
+    Name(lineno=4, name="print", is_all=False),
+    Name(lineno=4, name="defaultdict", is_all=False),
+]
+IMPORTS: list[Union[Import, ImportFrom]] = [
+    ImportFrom(
+        lineno=1,
+        column=1,
+        name="_collections",
+        package="_collections",
+        star=True,
+        suggestions=[],
+    ),
+    ImportFrom(
+        lineno=2,
+        column=1,
+        name="defaultdict",
+        package="collections",
+        star=False,
+        suggestions=[],
+    ),
+]
+UNUSED_IMPORTS: list[Union[Import, ImportFrom]] = [
+    ImportFrom(
+        lineno=1,
+        column=1,
+        name="_collections",
+        package="_collections",
+        star=True,
+        suggestions=[],
+    ),
+]

tests/cases/analyzer/star_import/star_imports.py

@@ -52,7 +52,7 @@
         name="json",
         package="json",
         star=True,
-        suggestions=["JSONEncoder"],
+        suggestions=[],
     ),
     ImportFrom(
         lineno=6,
@@ -70,7 +70,7 @@
         name="json",
         package="json",
         star=True,
-        suggestions=["JSONEncoder"],
+        suggestions=[],
     ),
     ImportFrom(
         lineno=4,

tests/cases/refactor/star_import/2.py

@@ -1,5 +1,4 @@
 from json import JSONEncoder
-from json import JSONEncoder
 
 
 print(JSONEncoder)

tests/cases/refactor/star_import/partial_overlap_star_imports.py

@@ -0,0 +1,6 @@
+from collections import Counter
+from _collections import defaultdict, deque
+
+print(Counter)
+print(defaultdict)
+print(deque)

tests/cases/refactor/star_import/star_import_with_explicit.py

@@ -0,0 +1,3 @@
+from collections import defaultdict
+
+print(defaultdict)

tests/cases/refactor/star_import/star_imports.py

@@ -1,6 +1,5 @@
 from re import match, search
 from json import JSONEncoder
-from json import JSONEncoder
 
 
 print(match)

tests/cases/source/star_import/partial_overlap_star_imports.py

@@ -0,0 +1,6 @@
+from collections import *
+from _collections import *
+
+print(Counter)
+print(defaultdict)
+print(deque)