Merge pull request #4132 from blueyed/pdb-internal-dupe

Do not print (duplicate) INTERNALERROR with --pdb.

changelog/4132.bugfix.rst

@@ -0,0 +1 @@
+Fix duplicate printing of internal errors when using ``--pdb``.

src/_pytest/debugging.py

@@ -109,9 +109,6 @@ class PdbInvoke(object):
         _enter_pdb(node, call.excinfo, report)
 
     def pytest_internalerror(self, excrepr, excinfo):
-        for line in str(excrepr).split("\n"):
-            sys.stderr.write("INTERNALERROR> %s\n" % line)
-            sys.stderr.flush()
         tb = _postmortem_traceback(excinfo)
         post_mortem(tb)
 

testing/test_pdb.py

@@ -334,8 +334,20 @@ class TestPDB(object):
         )
         p1 = testdir.makepyfile("def test_func(): pass")
         child = testdir.spawn_pytest("--pdb %s" % p1)
-        # child.expect(".*import pytest.*")
         child.expect("Pdb")
+
+        # INTERNALERROR is only displayed once via terminal reporter.
+        assert (
+            len(
+                [
+                    x
+                    for x in child.before.decode().splitlines()
+                    if x.startswith("INTERNALERROR> Traceback")
+                ]
+            )
+            == 1
+        )
+
         child.sendeof()
         self.flush(child)
 
@@ -525,7 +537,7 @@ class TestPDB(object):
             """
             def pytest_enter_pdb(config):
                 assert config.testing_verification == 'configured'
-                print 'enter_pdb_hook'
+                print('enter_pdb_hook')
 
             def pytest_configure(config):
                 config.testing_verification = 'configured'
@@ -562,7 +574,7 @@ class TestPDB(object):
             custom_pdb="""
             class CustomPdb(object):
                 def set_trace(*args, **kwargs):
-                    print 'custom set_trace>'
+                    print('custom set_trace>')
          """
         )
         p1 = testdir.makepyfile(