SysCaptureBinary: decode in writeorg

Fixes pytest-dev#6871.

src/_pytest/capture.py

@@ -687,7 +687,8 @@ def resume(self):
         setattr(sys, self.name, self.tmpfile)
         self._state = "resumed"
 
-    def writeorg(self, data):
+    def writeorg(self, data: str) -> None:
+        data = data.decode(self._old.encoding)
         self._old.write(data)
         self._old.flush()
 
@@ -701,6 +702,10 @@ def snap(self):
         self.tmpfile.truncate()
         return res
 
+    def writeorg(self, data: str) -> None:
+        self._old.write(data)
+        self._old.flush()
+
 
 class TeeSysCapture(SysCapture):
     def __init__(self, fd, tmpfile=None):

testing/test_capture.py

@@ -19,6 +19,7 @@
 from _pytest.capture import CaptureResult
 from _pytest.capture import MultiCapture
 from _pytest.config import ExitCode
+from _pytest.pytester import Testdir
 
 # note: py.io capture tests where copied from
 # pylib 1.4.20.dev2 (rev 13d9af95547e)
@@ -62,6 +63,23 @@ def test_CaptureResult() -> None:
     assert str(cr) == repr_
 
 
+def test_capsysbinary(testdir: Testdir) -> None:
+    p1 = testdir.makepyfile(
+        """
+        def test(capsysbinary):
+            print("hello")
+            assert False, "trigger_failure"
+        """
+    )
+    result = testdir.runpytest(str(p1))
+    result.stdout.fnmatch_lines([
+        'E       assert False',
+        '*- Captured stdout call -*',
+        'hello',
+    ])
+    assert result.ret == 1
+
+
 class TestCaptureManager:
     def test_getmethod_default_no_fd(self, monkeypatch):
         from _pytest.capture import pytest_addoption