bpo-32691: Use mod_spec.parent when running modules with pdb (pythonGH-5474)

Previously the module name was used, which broke relative imports when pdb was run against a plain module or submodule.

Author: mariocj89

Lib/pdb.py

@@ -1532,7 +1532,7 @@ def _runmodule(self, module_name):
  __main__.__dict__.update({
  "__name__": "__main__",
  "__file__": self.mainpyfile,
- "__package__": module_name,
+ "__package__": mod_spec.parent,
  "__loader__": mod_spec.loader,
  "__spec__": mod_spec,
  "__builtins__": __builtins__,

Lib/test/test_pdb.py

@@ -1447,10 +1447,41 @@ def test_relative_imports(self):
  quit
  """
  stdout, _ = self._run_pdb(['-m', self.module_name], commands)
- self.assertTrue(any("VAR from module" in l for l in stdout.splitlines()))
+ self.assertTrue(any("VAR from module" in l for l in stdout.splitlines()), stdout)
  self.assertTrue(any("VAR from top" in l for l in stdout.splitlines()))
  self.assertTrue(any("second var" in l for l in stdout.splitlines()))
 
+ def test_relative_imports_on_plain_module(self):
+ # Validates running a plain module. See bpo32691
+ self.module_name = 't_main'
+ support.rmtree(self.module_name)
+ main_file = self.module_name + '/runme.py'
+ init_file = self.module_name + '/__init__.py'
+ module_file = self.module_name + '/module.py'
+ self.addCleanup(support.rmtree, self.module_name)
+ os.mkdir(self.module_name)
+ with open(init_file, 'w') as f:
+ f.write(textwrap.dedent("""
+ top_var = "VAR from top"
+ """))
+ with open(main_file, 'w') as f:
+ f.write(textwrap.dedent("""
+ from . import module
+ pass # We'll stop here and print the vars
+ """))
+ with open(module_file, 'w') as f:
+ f.write(textwrap.dedent("""
+ var = "VAR from module"
+ """))
+ commands = """
+ b 3
+ c
+ p module.var
+ quit
+ """
+ stdout, _ = self._run_pdb(['-m', self.module_name + '.runme'], commands)
+ self.assertTrue(any("VAR from module" in l for l in stdout.splitlines()), stdout)
+
 
 def load_tests(*args):
  from test import test_pdb

Misc/NEWS.d/next/Library/2018-02-01-15-53-35.bpo-32691.VLWVTq.rst

@@ -0,0 +1 @@
+Use mod_spec.parent when running modules with pdb