core[patch]: Speed up unit tests for imports (#23837)

Speed up unit tests for imports

libs/core/tests/unit_tests/test_imports.py

@@ -1,9 +1,9 @@
+import concurrent.futures
 import glob
 import importlib
 import subprocess
 from pathlib import Path
-
-import pytest
+from typing import Tuple
 
 
 def test_importable_all() -> None:
@@ -17,11 +17,40 @@ def test_importable_all() -> None:
         for cls_ in all_:
             getattr(module, cls_)
 
-        # Test import in isolation
-        # Note: ImportErrors due to circular imports can be raised
-        # for one sequence of imports but not another.
+
+def try_to_import(module_name: str) -> Tuple[int, str]:
+    """Try to import a module via subprocess."""
+    module = importlib.import_module("langchain_core." + module_name)
+    all_ = getattr(module, "__all__", [])
+    for cls_ in all_:
+        getattr(module, cls_)
+
     result = subprocess.run(
         ["python", "-c", f"import langchain_core.{module_name}"],
     )
-        if result.returncode != 0:
-            pytest.fail(f"Failed to import {module_name}.")
+    return result.returncode, module_name
+
+
+def test_importable_all_via_subprocess() -> None:
+    """Test import in isolation.
+
+    Note: ImportErrors due to circular imports can be raised
+          for one sequence of imports but not another.
+    """
+    module_names = []
+    for path in glob.glob("../core/langchain_core/*"):
+        relative_path = Path(path).parts[-1]
+        if relative_path.endswith(".typed"):
+            continue
+        module_name = relative_path.split(".")[0]
+        module_names.append(module_name)
+
+    with concurrent.futures.ThreadPoolExecutor(max_workers=10) as executor:
+        futures = [
+            executor.submit(try_to_import, module_name) for module_name in module_names
+        ]
+        for future in concurrent.futures.as_completed(futures):
+            result = future.result()  # Will raise an exception if the callable raised
+            code, module_name = result
+            if code != 0:
+                raise ValueError(f"Failed to import {module_name}.")