Fix regression making --pdb unusable without configured reruns

changes/342.bugfix.rst

@@ -0,0 +1 @@
+Fix a regression in version 16.5 which made ``--pdb`` unusable even when no reruns were configured.

src/pytest_rerunfailures.py

@@ -178,6 +178,16 @@ def pytest_addoption(parser):
     )
 
 
+def _get_global_reruns(config):
+    reruns = config.getvalue("reruns")
+    if reruns is not None:
+        return reruns
+
+    with suppress(TypeError, ValueError):
+        reruns = int(config.getini("reruns"))
+    return reruns
+
+
 # making sure the options make sense
 # should run before / at the beginning of pytest_cmdline_main
 def check_options(config):
@@ -187,7 +197,8 @@ def check_options(config):
         and config.option.max_suite_reruns < 0
     ):
         raise pytest.UsageError("--max-suite-reruns must be >= 0")
-    if not val("collectonly") and config.option.reruns != 0:
+    reruns = config.getvalue("force_reruns") or _get_global_reruns(config)
+    if not val("collectonly") and reruns:
         if config.option.usepdb:  # a core option
             raise pytest.UsageError("--reruns incompatible with --pdb")
 
@@ -196,17 +207,6 @@ def _get_marker(item):
     return item.get_closest_marker("flaky")
 
 
-def _get_global_reruns(item):
-    reruns = item.session.config.getvalue("reruns")
-    if reruns is not None:
-        return reruns
-
-    reruns = None
-    with suppress(TypeError, ValueError):
-        reruns = int(item.session.config.getini("reruns"))
-    return reruns
-
-
 def get_reruns_count(item):
     reruns = item.session.config.getvalue("force_reruns")
     if reruns is not None:
@@ -225,12 +225,12 @@ def get_reruns_count(item):
             marker_reruns = 1
 
         if item.session.config.getvalue("reruns_mode") == "append":
-            global_reruns = _get_global_reruns(item)
+            global_reruns = _get_global_reruns(item.session.config)
             if global_reruns is not None:
                 return marker_reruns + global_reruns
         return marker_reruns
 
-    return _get_global_reruns(item)
+    return _get_global_reruns(item.session.config)
 
 
 def get_reruns_delay(item):
@@ -945,6 +945,12 @@ def pytest_runtest_protocol(item, nextitem):
         # flaky
         return
 
+    if reruns and item.session.config.option.usepdb:
+        # the global options are already rejected in check_options(); this
+        # catches reruns requested via the flaky marker, which are only
+        # known once the item is available
+        raise pytest.UsageError("--reruns incompatible with --pdb")
+
     delay = get_reruns_delay(item)
     delay_backoff_factor = get_reruns_delay_backoff_factor(item)
     parallel = not is_master(item.config)

tests/test_pytest_rerunfailures.py

@@ -75,6 +75,44 @@ def test_error_when_run_with_pdb(testdir):
     result.stderr.fnmatch_lines_random("ERROR: --reruns incompatible with --pdb")
 
 
+def test_no_error_when_run_with_pdb_without_reruns(testdir):
+    testdir.makepyfile("def test_pass(): pass")
+    result = testdir.runpytest("--pdb")
+    assert_outcomes(result)
+
+
+def test_no_error_when_run_with_pdb_and_zero_reruns(testdir):
+    testdir.makepyfile("def test_pass(): pass")
+    result = testdir.runpytest("--reruns", "0", "--pdb")
+    assert_outcomes(result)
+
+
+def test_error_when_run_with_pdb_and_reruns_ini(testdir):
+    testdir.makepyfile("def test_pass(): pass")
+    testdir.makeini("[pytest]\nreruns = 1\n")
+    result = testdir.runpytest("--pdb")
+    result.stderr.fnmatch_lines_random("ERROR: --reruns incompatible with --pdb")
+
+
+def test_error_when_run_with_pdb_and_force_reruns(testdir):
+    testdir.makepyfile("def test_pass(): pass")
+    result = testdir.runpytest("--force-reruns", "1", "--pdb")
+    result.stderr.fnmatch_lines_random("ERROR: --reruns incompatible with --pdb")
+
+
+def test_error_when_run_with_pdb_and_flaky_marker(testdir):
+    testdir.makepyfile(
+        """
+        import pytest
+
+        @pytest.mark.flaky(reruns=1)
+        def test_pass(): pass
+        """
+    )
+    result = testdir.runpytest("--pdb")
+    result.stderr.fnmatch_lines_random("*--reruns incompatible with --pdb")
+
+
 def test_no_rerun_on_pass(testdir):
     testdir.makepyfile("def test_pass(): pass")
     result = testdir.runpytest("--reruns", "1")