DEVOPS-751 fix: improve stream handling in sfdx for Windows compatibility (#10)

* DEVOPS-751 fix: improve stream handling in sfdx for Windows compatibility

* DEVOPS-751 chore: refine error handling in _capture_to_text_stream for better robustness

* DEVOPS-751 style: remove unnecessary blank line in _capture_to_text_stream function

Author: dipakparmar

cumulusci/core/sfdx.py

@@ -19,6 +19,41 @@
 logger = logging.getLogger(__name__)
 
 
+def _capture_to_text_stream(stream: T.Any, encoding: str) -> io.StringIO:
+    """Convert a capture stream into a readable text buffer.
+
+    sarge's Capture objects do not always implement ``flush`` on Windows,
+    which breaks ``io.TextIOWrapper``. This helper normalizes the stream
+    into an in-memory text buffer that supports the APIs the rest of CCI
+    expects (``read``, iteration, etc.) without relying on ``flush``.
+    """
+
+    if stream is None:
+        return io.StringIO("")
+
+    data: T.Any = None
+    getter = getattr(stream, "getvalue", None)
+    if callable(getter):
+        try:
+            data = getter()
+        except (AttributeError, IOError, OSError, ValueError):
+            data = None
+    if data is None:
+        reader = getattr(stream, "read", None)
+        if callable(reader):
+            try:
+                data = reader()
+            except (AttributeError, IOError, OSError, ValueError):
+                data = None
+
+    if data is None:
+        return io.StringIO("")
+    if isinstance(data, str):
+        return io.StringIO(data)
+    if isinstance(data, (bytes, bytearray)):
+        return io.StringIO(data.decode(encoding, errors="replace"))
+    return io.StringIO(str(data))
+
 def sfdx(
     command,
     username=None,
@@ -56,8 +91,9 @@ def sfdx(
     )
     p.run()
     if capture_output:
-        p.stdout_text = io.TextIOWrapper(p.stdout, encoding=sys.stdout.encoding)
-        p.stderr_text = io.TextIOWrapper(p.stderr, encoding=sys.stdout.encoding)
+        encoding = sys.stdout.encoding or sys.getdefaultencoding() or "utf-8"
+        p.stdout_text = _capture_to_text_stream(p.stdout, encoding)
+        p.stderr_text = _capture_to_text_stream(p.stderr, encoding)
     if check_return and p.returncode:
         message = f"Command exited with return code {p.returncode}"
         if capture_output:

cumulusci/core/tests/test_sfdx.py

@@ -46,6 +46,26 @@ def test_check_return(self, Command):
             sfdx("cmd", check_return=True)
         assert str(exc_info.value) == "Command exited with return code 1:\nEgads!"
 
+    @mock.patch("sarge.Command")
+    def test_capture_without_flush_is_wrapped(self, Command):
+        class DummyCapture:
+            def __init__(self, payload):
+                self._payload = payload
+
+            def read(self, *_args, **_kwargs):
+                return self._payload
+
+        Command.return_value.returncode = 0
+        Command.return_value.stdout = DummyCapture(b"ok")
+        Command.return_value.stderr = DummyCapture(b"")
+
+        result = sfdx("cmd")
+
+        assert isinstance(result.stdout_text, io.StringIO)
+        assert result.stdout_text.read() == "ok"
+        result.stdout_text.seek(0)
+        assert list(result.stdout_text) == ["ok"]
+
 
 @mock.patch("sarge.Command")
 def test_get_default_devhub_username(Command):