Test hygiene: forget the refused study, quiet _Tee on a closed stream, wait for connector recovery

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01WgBfkm4rCmtd1T4vHWjEPx

backend/tests/test_cli.py

@@ -636,6 +636,8 @@ def test_two_files_of_one_name_are_refused(tmp_path) -> None:
     where it sits; this is the spelling that still gets there — two files
     named on the command line, each rooted at its own directory.
     """
+    import sys
+
     import pytest
 
     from fluksio.sdk import SyncError
@@ -647,9 +649,14 @@ def test_two_files_of_one_name_are_refused(tmp_path) -> None:
 
     first = tmp_path / "s1" / "study.py"
     second = tmp_path / "s2" / "study.py"
-    _import(*_module_of(first), first)
-    with pytest.raises(SyncError, match="both import as 'study'"):
-        _import(*_module_of(second), second)
+    roots = {str(tmp_path / "s1"), str(tmp_path / "s2")}
+    try:
+        _import(*_module_of(first), first)
+        with pytest.raises(SyncError, match="both import as 'study'"):
+            _import(*_module_of(second), second)
+    finally:
+        sys.modules.pop("study", None)
+        sys.path[:] = [entry for entry in sys.path if entry not in roots]
 
 
 def test_how_long_ago_reads_like_a_duration() -> None: