Revisit some tests

testing/conftest.py

@@ -9,6 +9,8 @@
 from _pytest.pytester import RunResult
 
 if TYPE_CHECKING:
+    from typing import Generator
+
     from _pytest.config import Config
 
 
@@ -18,19 +20,36 @@ def pytest_addoption(parser):
     )
 
 
-if sys.gettrace():
+orig_trace = sys.gettrace()
+
+if orig_trace:
 
     @pytest.fixture(autouse=True)
     def restore_tracing():
         """Restore tracing function (when run with Coverage.py).
 
         https://bugs.python.org/issue37011
         """
-        orig_trace = sys.gettrace()
+        assert orig_trace == sys.gettrace(), (orig_trace, sys.gettrace())
         yield
         if sys.gettrace() != orig_trace:
             sys.settrace(orig_trace)
 
+    orig_settrace = sys.settrace
+
+    def wrapped_settrace(tracer):
+        if tracer is None:
+            orig_settrace(orig_trace)
+        else:
+            orig_settrace(tracer)
+
+    @pytest.fixture(autouse=True)
+    def wrap_sys_settrace_for_pdb_with_coverage(
+        monkeypatch,
+    ) -> "Generator[None, None, None]":
+        monkeypatch.setattr("sys.settrace", wrapped_settrace)
+        yield
+
 
 @pytest.hookimpl
 def pytest_runtest_setup(item):

testing/test_debugging.py

@@ -776,19 +776,29 @@ def do_continue(self, arg):
             assert "> PDB continue >" in rest
         assert "= 1 passed in" in rest
 
-    def test_pytest_set_trace_used_outside_of_test(self, testdir):
+    def test_pytest_set_trace_used_outside_of_test(self, testdir: "Testdir") -> None:
         p1 = testdir.makepyfile(
             """
             import pytest
             pytest.set_trace()
             x = 5
-        """
+            pytest.set_trace(header="custom_header")
+            x = 6
+            """
         )
-        child = testdir.spawn("{} {}".format(sys.executable, p1))
-        child.expect("x = 5")
-        child.expect("Pdb")
-        child.sendeof()
-        self.flush(child)
+        result = testdir.run(sys.executable, p1, stdin="c\nc\n")
+        result.stdout.fnmatch_lines(
+            [
+                "> */test_pytest_set_trace_used_outside_of_test.py(3)<module>()",
+                "-> x = 5",
+                "(Pdb) custom_header",
+                "> */test_pytest_set_trace_used_outside_of_test.py(5)<module>()",
+                "-> x = 6",
+                "(Pdb) ",
+            ],
+            complete=True,
+        )
+        assert result.ret == 0
 
     def test_pdb_used_in_generate_tests(self, testdir):
         p1 = testdir.makepyfile(