pdb: support kwargs with `pdb.set_trace`

This handles `header` similar to Python 3.7 does it, and forwards any
other keyword arguments to the Pdb constructor.

This allows for `__import__("pdb").set_trace(skip=["foo.*"])`.

Fixes https://github.com/pytest-dev/pytest/issues/4416.

1 files changed, 30 insertions, 1 deletions

diff --git a/testing/test_pdb.py b/testing/test_pdb.py
index dd349454b..41b4badda 100644
--- a/testing/test_pdb.py
+++ b/testing/test_pdb.py
@@ -390,6 +390,28 @@ class TestPDB(object):
         assert "hello17" in rest  # out is captured
         self.flush(child)
 
+    def test_pdb_set_trace_kwargs(self, testdir):
+        p1 = testdir.makepyfile(
+            """
+            import pytest
+            def test_1():
+                i = 0
+                print("hello17")
+                pytest.set_trace(header="== my_header ==")
+                x = 3
+        """
+        )
+        child = testdir.spawn_pytest(str(p1))
+        child.expect("== my_header ==")
+        assert "PDB set_trace" not in child.before.decode()
+        child.expect("Pdb")
+        child.sendeof()
+        rest = child.read().decode("utf-8")
+        assert "1 failed" in rest
+        assert "def test_1" in rest
+        assert "hello17" in rest  # out is captured
+        self.flush(child)
+
     def test_pdb_set_trace_interception(self, testdir):
         p1 = testdir.makepyfile(
             """
@@ -634,6 +656,12 @@ class TestPDB(object):
         testdir.makepyfile(
             custom_pdb="""
             class CustomPdb(object):
+                def __init__(self, *args, **kwargs):
+                    skip = kwargs.pop("skip")
+                    assert skip == ["foo.*"]
+                    print("__init__")
+                    super(CustomPdb, self).__init__(*args, **kwargs)
+
                 def set_trace(*args, **kwargs):
                     print('custom set_trace>')
          """
@@ -643,12 +671,13 @@ class TestPDB(object):
             import pytest
 
             def test_foo():
-                pytest.set_trace()
+                pytest.set_trace(skip=['foo.*'])
         """
         )
         monkeypatch.setenv("PYTHONPATH", str(testdir.tmpdir))
         child = testdir.spawn_pytest("--pdbcls=custom_pdb:CustomPdb %s" % str(p1))
 
+        child.expect("__init__")
         child.expect("custom set_trace>")
         self.flush(child)