bpo-32206: Pdb can now run modules

Doc/library/pdb.rst

@@ -61,6 +61,12 @@ useful than quitting the debugger upon program's exit.
    :file:`pdb.py` now accepts a ``-c`` option that executes commands as if given
    in a :file:`.pdbrc` file, see :ref:`debugger-commands`.
 
+.. versionadded:: 3.7
+   :file:`pdb.py` now accepts a ``-m`` option that execute modules similar to the way
+   ``python3 -m`` does. As with a script, the debugger will pause execution just
+   before the first line of the module.
+
+
 The typical usage to break into the debugger from a running program is to
 insert ::
 

Doc/whatsnew/3.7.rst

@@ -357,6 +357,10 @@ pdb
 argument.  If given, this is printed to the console just before debugging
 begins.  (Contributed by Barry Warsaw in :issue:`31389`.)
 
+pdb command line now accepts `-m module_name` as an alternative to
+script file. (Contributed by Mario Corchero in :issue:`32206`.)
+
+
 re
 --
 

Lib/pdb.py

@@ -1521,6 +1521,24 @@ def lookupmodule(self, filename):
                 return fullname
         return None
 
+    def _runmodule(self, module_name):
+        self._wait_for_mainpyfile = True
+        self._user_requested_quit = False
+        import runpy
+        mod_name, mod_spec, code = runpy._get_module_details(module_name)
+        self.mainpyfile = self.canonic(code.co_filename)
+        import __main__
+        __main__.__dict__.clear()
+        __main__.__dict__.update({
+            "__name__": "__main__",
+            "__file__": self.mainpyfile,
+            "__package__": module_name,
+            "__loader__": mod_spec.loader,
+            "__spec__": mod_spec,
+            "__builtins__": __builtins__,
+        })
+        self.run(code)
+
     def _runscript(self, filename):
         # The script has to run in __main__ namespace (or imports from
         # __main__ will break).
@@ -1635,29 +1653,33 @@ def help():
 def main():
     import getopt
 
-    opts, args = getopt.getopt(sys.argv[1:], 'hc:', ['--help', '--command='])
+    opts, args = getopt.getopt(sys.argv[1:], 'mhc:', ['--help', '--command='])
 
     if not args:
         print(_usage)
         sys.exit(2)
 
     commands = []
+    run_as_module = False
     for opt, optarg in opts:
         if opt in ['-h', '--help']:
             print(_usage)
             sys.exit()
         elif opt in ['-c', '--command']:
             commands.append(optarg)
+        elif opt in ['-m']:
+            run_as_module = True
 
     mainpyfile = args[0]     # Get script filename
-    if not os.path.exists(mainpyfile):
+    if not run_as_module and not os.path.exists(mainpyfile):
         print('Error:', mainpyfile, 'does not exist')
         sys.exit(1)
 
     sys.argv[:] = args      # Hide "pdb.py" and pdb options from argument list
 
     # Replace pdb's dir with script's dir in front of module search path.
-    sys.path[0] = os.path.dirname(mainpyfile)
+    if not run_as_module:
+        sys.path[0] = os.path.dirname(mainpyfile)
 
     # Note on saving/restoring sys.argv: it's a good idea when sys.argv was
     # modified by the script being debugged. It's a bad idea when it was
@@ -1667,7 +1689,10 @@ def main():
     pdb.rcLines.extend(commands)
     while True:
         try:
-            pdb._runscript(mainpyfile)
+            if run_as_module:
+                pdb._runmodule(mainpyfile)
+            else:
+                pdb._runscript(mainpyfile)
             if pdb._user_requested_quit:
                 break
             print("The program finished and will be restarted")

Lib/test/test_pdb.py

@@ -938,26 +938,47 @@ def test_pdb_issue_20766():
     pdb 2: <built-in function default_int_handler>
     """
 
+
 class PdbTestCase(unittest.TestCase):
+    def tearDown(self):
+        support.unlink(support.TESTFN)
 
-    def run_pdb(self, script, commands):
-        """Run 'script' lines with pdb and the pdb 'commands'."""
-        filename = 'main.py'
-        with open(filename, 'w') as f:
-            f.write(textwrap.dedent(script))
-        self.addCleanup(support.unlink, filename)
+    def _run_pdb(self, pdb_args, commands):
         self.addCleanup(support.rmtree, '__pycache__')
-        cmd = [sys.executable, '-m', 'pdb', filename]
-        stdout = stderr = None
-        with subprocess.Popen(cmd, stdout=subprocess.PIPE,
-                                   stdin=subprocess.PIPE,
-                                   stderr=subprocess.STDOUT,
-                                   ) as proc:
+        cmd = [sys.executable, '-m', 'pdb'] + pdb_args
+        with subprocess.Popen(
+                cmd,
+                stdout=subprocess.PIPE,
+                stdin=subprocess.PIPE,
+                stderr=subprocess.STDOUT,
+        ) as proc:
             stdout, stderr = proc.communicate(str.encode(commands))
         stdout = stdout and bytes.decode(stdout)
         stderr = stderr and bytes.decode(stderr)
         return stdout, stderr
 
+    def run_pdb_script(self, script, commands):
+        """Run 'script' lines with pdb and the pdb 'commands'."""
+        filename = 'main.py'
+        with open(filename, 'w') as f:
+            f.write(textwrap.dedent(script))
+        self.addCleanup(support.unlink, filename)
+        return self._run_pdb([filename], commands)
+
+    def run_pdb_module(self, script, commands):
+        """Runs the script code as part of a module"""
+        self.module_name = 't_main'
+        support.rmtree(self.module_name)
+        main_file = self.module_name + '/__main__.py'
+        init_file = self.module_name + '/__init__.py'
+        os.mkdir(self.module_name)
+        with open(init_file, 'w') as f:
+            pass
+        with open(main_file, 'w') as f:
+            f.write(textwrap.dedent(script))
+        self.addCleanup(support.rmtree, self.module_name)
+        return self._run_pdb(['-m', self.module_name], commands)
+
     def _assert_find_function(self, file_content, func_name, expected):
         file_content = textwrap.dedent(file_content)
 
@@ -1034,7 +1055,7 @@ def bar():
         with open('bar.py', 'w') as f:
             f.write(textwrap.dedent(bar))
         self.addCleanup(support.unlink, 'bar.py')
-        stdout, stderr = self.run_pdb(script, commands)
+        stdout, stderr = self.run_pdb_script(script, commands)
         self.assertTrue(
             any('main.py(5)foo()->None' in l for l in stdout.splitlines()),
             'Fail to step into the caller after a return')
@@ -1071,7 +1092,7 @@ def test_issue16180(self):
         script = "def f: pass\n"
         commands = ''
         expected = "SyntaxError:"
-        stdout, stderr = self.run_pdb(script, commands)
+        stdout, stderr = self.run_pdb_script(script, commands)
         self.assertIn(expected, stdout,
             '\n\nExpected:\n{}\nGot:\n{}\n'
             'Fail to handle a syntax error in the debuggee.'
@@ -1119,13 +1140,119 @@ def test_header(self):
             pdb.set_trace(header=header)
         self.assertEqual(stdout.getvalue(), header + '\n')
 
-    def tearDown(self):
-        support.unlink(support.TESTFN)
+    def test_run_module(self):
+        script = """print("SUCCESS")"""
+        commands = """
+            continue
+            quit
+        """
+        stdout, stderr = self.run_pdb_module(script, commands)
+        self.assertTrue(any("SUCCESS" in l for l in stdout.splitlines()), stdout)
+
+    def test_module_is_run_as_main(self):
+        script = """
+            if __name__ == '__main__':
+                print("SUCCESS")
+        """
+        commands = """
+            continue
+            quit
+        """
+        stdout, stderr = self.run_pdb_module(script, commands)
+        self.assertTrue(any("SUCCESS" in l for l in stdout.splitlines()), stdout)
+
+    def test_breakpoint(self):
+        script = """
+            if __name__ == '__main__':
+                pass
+                print("SUCCESS")
+                pass
+        """
+        commands = """
+            b 3
+            quit
+        """
+        stdout, stderr = self.run_pdb_module(script, commands)
+        self.assertTrue(any("Breakpoint 1 at" in l for l in stdout.splitlines()), stdout)
+        self.assertTrue(all("SUCCESS" not in l for l in stdout.splitlines()), stdout)
+
+    def test_run_pdb_with_pdb(self):
+        commands = """
+            c
+            quit
+        """
+        stdout, stderr = self._run_pdb(["-m", "pdb"], commands)
+        self.assertIn("Debug the Python program given by pyfile.", stdout.splitlines())
+
+    def test_module_without_a_main(self):
+        module_name = 't_main'
+        support.rmtree(module_name)
+        init_file = module_name + '/__init__.py'
+        os.mkdir(module_name)
+        with open(init_file, 'w') as f:
+            pass
+        self.addCleanup(support.rmtree, module_name)
+        stdout, stderr = self._run_pdb(['-m', module_name], "")
+        self.assertIn("ImportError: No module named t_main.__main__",
+                      stdout.splitlines())
+
+    def test_blocks_at_first_code_line(self):
+        script = """
+                #This is a comment, on line 2
+
+                print("SUCCESS")
+        """
+        commands = """
+            quit
+        """
+        stdout, stderr = self.run_pdb_module(script, commands)
+        self.assertTrue(any("__main__.py(4)<module>()"
+                            in l for l in stdout.splitlines()), stdout)
+
+    def test_relative_imports(self):
+        self.module_name = 't_main'
+        support.rmtree(self.module_name)
+        main_file = self.module_name + '/__main__.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 top_var
+                from .module import var
+                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"
+                var2 = "second var"
+            """))
+        commands = """
+            b 5
+            c
+            p top_var
+            p var
+            p module.var2
+            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 top" in l for l in stdout.splitlines()))
+        self.assertTrue(any("second var" in l for l in stdout.splitlines()))
 
 
 def load_tests(*args):
     from test import test_pdb
-    suites = [unittest.makeSuite(PdbTestCase), doctest.DocTestSuite(test_pdb)]
+    suites = [
+        unittest.makeSuite(PdbTestCase),
+        doctest.DocTestSuite(test_pdb)
+    ]
     return unittest.TestSuite(suites)
 
 

Misc/NEWS.d/next/Library/2017-12-07-13-14-40.bpo-32206.obm4OM.rst

@@ -0,0 +1 @@
+Add support to run modules with pdb