Include full path in filename for linked filesystem files

src/CSET/cset_workflow/app/fetch_fcst/bin/fetch_data.py

@@ -110,10 +110,13 @@ def get_file(self, file_path: str, output_dir: str) -> bool:
             logging.warning("file_path does not match any files: %s", file_path)
         any_files_copied = False
         for f in file_paths:
-            file = Path(f)
+            file = Path(f).absolute()
             try:
-                # We know file exists from glob.
-                os.symlink(file.absolute(), f"{output_dir}/{file.name}")
+                # Save to a filename derived from the full path, to
+                # differentiate similarly named files from different
+                # directories.
+                # `)` replaces `/` as it can be in file names.
+                os.symlink(file, f"{output_dir}/{')'.join(file.parts)}")
                 any_files_copied = True
             except OSError as err:
                 logging.warning("Failed to copy %s, error: %s", file, err)

tests/workflow_utils/test_fetch_data.py

@@ -237,10 +237,10 @@ def test_FilesystemFileRetriever(tmp_path):
     # Correct return value.
     assert files_found
     # Symlinks created.
-    assert (tmp_path / "exeter_em01.nc").exists(follow_symlinks=False)
-    assert (tmp_path / "exeter_em02.nc").exists(follow_symlinks=False)
+    retrieved_files = sorted(tmp_path.glob("*exeter_em0?.nc"))
+    assert len(retrieved_files) == 2
     # Check symlink points to correct file.
-    with open((tmp_path / "exeter_em01.nc"), "rb") as fp:
+    with open(retrieved_files[0], "rb") as fp:
         digest = hashlib.file_digest(fp, "sha256").hexdigest()
     assert digest == "23761fd2456b2dbbb18f35fa4909561569af0851ebda6e3705e70e366c86ac09"