Fix a border case on LocalFileSystem.copy_from_local where the target path is relative (#504)

Without this fix the library would try and fail to create a parent directory named ''

Author: tramora

khiops/core/internals/filesystems.py

@@ -477,7 +477,7 @@ def remove(self):
 
     def copy_from_local(self, local_path):
         directory = os.path.dirname(self.path)
-        if not os.path.isdir(directory):
+        if len(directory) > 0 and not os.path.isdir(directory):
             os.makedirs(directory)
         shutil.copy(local_path, self.path)
 

tests/test_core.py

@@ -10,6 +10,7 @@
 import json
 import math
 import os
+import pathlib
 import shutil
 import tempfile
 import textwrap
@@ -22,6 +23,7 @@
 
 import khiops
 import khiops.core as kh
+import khiops.core.internals.filesystems as fs
 from khiops.core import KhiopsRuntimeError
 from khiops.core.internals.io import KhiopsOutputWriter
 from khiops.core.internals.runner import KhiopsLocalRunner, KhiopsRunner
@@ -3186,5 +3188,40 @@ def test_raise_exception_on_error_case_without_a_message(self):
         self.assertEqual(output_msg, expected_msg)
 
 
+class LocalFileSystemTests(unittest.TestCase):
+    """Test the methods of the `LocalFileSystem`"""
+
+    def setUp(self):
+        self.current_dir = os.getcwd()  # save the current directory
+
+    def test_copy_from_local(self):
+        """Ensure fs.copy_from_local behaves as expected"""
+
+        tmp_dir = "/tmp"
+        os.chdir(tmp_dir)  # folder location of the target files
+        # target file names that will be created
+        target_file_name1 = "khiops-python-unit-test-target1.txt"
+        target_file_name2 = "khiops-python-unit-test-target2.txt"
+        with tempfile.NamedTemporaryFile(
+            prefix="khiops-python-unit-test-source", dir=tmp_dir
+        ) as tmp_file_source:
+            try:
+                fs.copy_from_local(target_file_name1, tmp_file_source.name)
+                fs.copy_from_local(f"./{target_file_name2}", tmp_file_source.name)
+                fs.copy_from_local(
+                    "./created_folder/khiops-python-unit-test-target3.txt",
+                    tmp_file_source.name,
+                )
+            except FileNotFoundError as exc:
+                self.fail(f"'copy_from_local' failed unexpectedly : {str(exc)}")
+            finally:
+                pathlib.Path(target_file_name1).unlink(missing_ok=True)
+                pathlib.Path(target_file_name1).unlink(missing_ok=True)
+                shutil.rmtree("./created_folder/", ignore_errors=True)
+
+    def tearDown(self):
+        os.chdir(self.current_dir)  # restore the current directory
+
+
 if __name__ == "__main__":
     unittest.main()