fix: Update imports when merging stubs

Issue-746: mkdocstrings/mkdocstrings#746

Author: pawamoy

src/_griffe/merger.py

@@ -51,6 +51,9 @@ def _merge_stubs_overloads(obj: Module | Class, stubs: Module | Class) -> None:
 
 
 def _merge_stubs_members(obj: Module | Class, stubs: Module | Class) -> None:
+    # Merge imports to later know if objects coming from the stubs were imported.
+    obj.imports.update(stubs.imports)
+
     for member_name, stub_member in stubs.members.items():
         if member_name in obj.members:
             # We don't merge imported stub objects that already exist in the concrete module.

tests/test_merger.py

@@ -36,3 +36,14 @@ def hello(value: str) -> str: ...
     ) as pkg:
         assert pkg["A.hello"].overloads
 
+
+def test_merge_imports() -> None:
+    """Assert that imports are merged correctly."""
+    with temporary_visited_package(
+        "package",
+        {
+            "mod.py": "import abc",
+            "mod.pyi": "import collections",
+        },
+    ) as pkg:
+        assert set(pkg["mod"].imports) == {"abc", "collections"}