pdb: handle capturing with fixtures only

src/_pytest/capture.py

@@ -107,6 +107,16 @@ class CaptureManager(object):
             return MultiCapture(out=False, err=False, in_=False)
         raise ValueError("unknown capturing method: %r" % method)  # pragma: no cover
 
+    def is_capturing(self):
+        if self.is_globally_capturing():
+            return "global"
+        capture_fixture = getattr(self._current_item, "_capture_fixture", None)
+        if capture_fixture is not None:
+            return (
+                "fixture %s" % self._current_item._capture_fixture.request.fixturename
+            )
+        return False
+
     # Global capturing control
 
     def is_globally_capturing(self):
@@ -134,6 +144,14 @@ class CaptureManager(object):
         if cap is not None:
             cap.suspend_capturing(in_=in_)
 
+    def suspend(self, in_=False):
+        self.suspend_fixture(self._current_item)
+        self.suspend_global_capture(in_)
+
+    def resume(self):
+        self.resume_global_capture()
+        self.resume_fixture(self._current_item)
+
     def read_global_capture(self):
         return self._global_capturing.readouterr()
 

src/_pytest/debugging.py

@@ -109,7 +109,7 @@ class pytestPDB(object):
         if cls._pluginmanager is not None:
             capman = cls._pluginmanager.getplugin("capturemanager")
             if capman:
-                capman.suspend_global_capture(in_=True)
+                capman.suspend(in_=True)
             tw = _pytest.config.create_terminal_writer(cls._config)
             tw.line()
             if cls._recursive_debug == 0:
@@ -117,10 +117,22 @@ class pytestPDB(object):
                 header = kwargs.pop("header", None)
                 if header is not None:
                     tw.sep(">", header)
-                elif capman and capman.is_globally_capturing():
-                    tw.sep(">", "PDB set_trace (IO-capturing turned off)")
                 else:
-                    tw.sep(">", "PDB set_trace")
+                    if capman:
+                        capturing = capman.is_capturing()
+                    else:
+                        capturing = False
+                    if capturing:
+                        if capturing == "global":
+                            tw.sep(">", "PDB set_trace (IO-capturing turned off)")
+                        else:
+                            tw.sep(
+                                ">",
+                                "PDB set_trace (IO-capturing turned off for %s)"
+                                % capturing,
+                            )
+                    else:
+                        tw.sep(">", "PDB set_trace")
 
             class _PdbWrapper(cls._pdb_cls, object):
                 _pytest_capman = capman
@@ -138,11 +150,18 @@ class pytestPDB(object):
                         tw = _pytest.config.create_terminal_writer(cls._config)
                         tw.line()
                         if cls._recursive_debug == 0:
-                            if self._pytest_capman.is_globally_capturing():
+                            capturing = self._pytest_capman.is_capturing()
+                            if capturing == "global":
                                 tw.sep(">", "PDB continue (IO-capturing resumed)")
+                            elif capturing:
+                                tw.sep(
+                                    ">",
+                                    "PDB continue (IO-capturing resumed for %s)"
+                                    % capturing,
+                                )
                             else:
                                 tw.sep(">", "PDB continue")
-                            self._pytest_capman.resume_global_capture()
+                            self._pytest_capman.resume()
                     cls._pluginmanager.hook.pytest_leave_pdb(
                         config=cls._config, pdb=self
                     )

testing/test_pdb.py

@@ -970,3 +970,52 @@ def test_quit_with_swallowed_SystemExit(testdir):
     rest = child.read().decode("utf8")
     assert "no tests ran" in rest
     TestPDB.flush(child)
+
+
+@pytest.mark.parametrize("fixture", ("capfd", "capsys"))
+def test_pdb_suspends_fixture_capturing(testdir, fixture):
+    """Using "-s" with pytest should suspend/resume fixture capturing."""
+    p1 = testdir.makepyfile(
+        """
+        def test_inner({fixture}):
+            import sys
+
+            print("out_inner_before")
+            sys.stderr.write("err_inner_before\\n")
+
+            __import__("pdb").set_trace()
+
+            print("out_inner_after")
+            sys.stderr.write("err_inner_after\\n")
+
+            out, err = {fixture}.readouterr()
+            assert out =="out_inner_before\\nout_inner_after\\n"
+            assert err =="err_inner_before\\nerr_inner_after\\n"
+        """.format(
+            fixture=fixture
+        )
+    )
+
+    child = testdir.spawn_pytest(str(p1) + " -s")
+
+    child.expect("Pdb")
+    before = child.before.decode("utf8")
+    assert (
+        "> PDB set_trace (IO-capturing turned off for fixture %s) >" % (fixture)
+        in before
+    )
+
+    # Test that capturing is really suspended.
+    child.sendline("p 40 + 2")
+    child.expect("Pdb")
+    assert "\r\n42\r\n" in child.before.decode("utf8")
+
+    child.sendline("c")
+    rest = child.read().decode("utf8")
+    assert "out_inner" not in rest
+    assert "err_inner" not in rest
+
+    TestPDB.flush(child)
+    assert child.exitstatus == 0
+    assert "= 1 passed in " in rest
+    assert "> PDB continue (IO-capturing resumed for fixture %s) >" % (fixture) in rest