Mock the failure to test the fallback.

Author: christinaholtNOAA

src/uwtools/tests/drivers/test_stager.py

@@ -3,14 +3,13 @@
 """
 
 from pathlib import Path
+from unittest.mock import patch
 
-from pytest import fixture
+from pytest import fixture, mark
 
 from uwtools.api.config import get_yaml_config
 from uwtools.drivers.stager import FileStager
-
-# Need one file on a non-/tmp disk for testing hardlink fallback
-B_FILE = Path("./b.foo").resolve()
+from uwtools.utils import tasks
 
 
 class NullDriver(FileStager):
@@ -24,14 +23,6 @@ def taskname(self, s):
         return f"Null {s}"
 
 
-def setup_module(module):  # noqa: ARG001
-    B_FILE.touch()
-
-
-def teardown_module(module):  # noqa: ARG001
-    B_FILE.unlink()
-
-
 @fixture
 def driver(tmp_path):
     i = tmp_path / "input"
@@ -42,15 +33,14 @@ def driver(tmp_path):
       tmp: %s
       files_to_copy:
         a.foo: '{{ tmp }}/input/a.foo'
-        b.foo: %s
+        b.foo: '{{ tmp }}/input/b.foo'
       files_to_link:
         c.foo: '{{ tmp }}/input/a.foo'
         d.foo: '{{ tmp }}/input/a.foo'
         output/<files>: !glob '{{ tmp }}/input/*.foo'
       files_to_hardlink:
-        e.foo: %s
-        f.foo: '{{ tmp }}/input/a.foo'
-      """ % (tmp_path, B_FILE, B_FILE)
+        e.foo: '{{ tmp }}/input/a.foo'
+      """ % (tmp_path)
     cfg = tmp_path / "config.yaml"
     cfg.write_text(config)
     return NullDriver(config_file=cfg, rundir=tmp_path)
@@ -62,14 +52,18 @@ def test_files_to_copy(driver, tmp_path):
     assert (tmp_path / "b.foo").is_file()
 
 
-def test_files_to_hardlink(driver, tmp_path):
-    driver.files_hardlinked()
-    a = tmp_path / "input" / "a.foo"
+@mark.parametrize("success", [True, False])
+def test_files_to_hardlink(driver, success, tmp_path):
     e = tmp_path / "e.foo"
-    f = tmp_path / "f.foo"
-    assert e.is_file()
-    assert not e.samefile(B_FILE)
-    assert a.samefile(f)
+    if success:
+        driver.files_hardlinked()
+        # It's a hardlink
+        assert e.stat().st_nlink == 2
+    else:
+        with patch.object(tasks.os, "link", side_effect=OSError()):
+            driver.files_hardlinked()
+        # It's a copy
+        assert e.stat().st_nlink == 1
 
 
 def test_files_to_link(driver, tmp_path):