Improve debugpy's capabilities (Cherry-pick of #15946)

src/python/pants/backend/python/goals/pytest_runner.py

@@ -68,7 +68,6 @@
 from pants.engine.unions import UnionMembership, UnionRule, union
 from pants.option.global_options import GlobalOptions
 from pants.util.logging import LogLevel
-from pants.util.strutil import softwrap
 
 logger = logging.getLogger()
 
@@ -410,32 +409,14 @@ async def debugpy_python_test(
     pytest: PyTest,
 ) -> TestDebugAdapterRequest:
     debugpy_pex = await Get(Pex, PexRequest, debugpy.to_pex_request())
-    if pytest.main.spec != "pytest":
-        logger.warning(
-            softwrap(
-                """
-                Ignoring custom [pytest].console_script/entry_point when using the debug adapter.
-                `debugpy` (Python's Debug Adapter) doesn't support this use-case yet.
-                """
-            )
-        )
 
     setup = await Get(
         TestSetup,
         TestSetupRequest(
             field_set,
             is_debug=True,
             main=debugpy.main,
-            prepend_argv=(
-                "--listen",
-                f"{debug_adapter.host}:{debug_adapter.port}",
-                "--wait-for-client",
-                # @TODO: Techincally we should use `pytest.main`, however `debugpy` doesn't support
-                # launching an entry_point.
-                # https://github.com/microsoft/debugpy/issues/955
-                "-m",
-                "pytest",
-            ),
+            prepend_argv=debugpy.get_args(debug_adapter, pytest.main),
             additional_pexes=(debugpy_pex,),
         ),
     )

src/python/pants/backend/python/goals/pytest_runner_integration_test.py

@@ -5,6 +5,7 @@
 
 import os
 import re
+import unittest.mock
 from textwrap import dedent
 
 import pytest
@@ -610,7 +611,7 @@ def test_debug_adaptor_request_argv(rule_runner: RuleRunner) -> None:
         "--listen",
         "127.0.0.1:5678",
         "--wait-for-client",
-        "-m",
-        "pytest",
+        "-c",
+        unittest.mock.ANY,
         "tests/python/pants_test/test_foo.py",
     )

src/python/pants/backend/python/subsystems/debugpy.py

@@ -7,15 +7,18 @@
 from pants.backend.python.goals.lockfile import GeneratePythonLockfile
 from pants.backend.python.subsystems.python_tool_base import PythonToolBase
 from pants.backend.python.subsystems.setup import PythonSetup
-from pants.backend.python.target_types import EntryPoint
+from pants.backend.python.target_types import ConsoleScript, EntryPoint, MainSpecification
 from pants.core.goals.generate_lockfiles import GenerateToolLockfileSentinel
+from pants.core.subsystems.debug_adapter import DebugAdapterSubsystem
 from pants.engine.rules import collect_rules, rule
 from pants.engine.unions import UnionRule
+from pants.option.option_types import ArgsListOption
 from pants.util.docutil import git_url
 
 
 class DebugPy(PythonToolBase):
     options_scope = "debugpy"
+    name = options_scope
     help = "An implementation of the Debug Adapter Protocol for Python (https://github.com/microsoft/debugpy)."
 
     default_version = "debugpy==1.6.0"
@@ -29,6 +32,37 @@ class DebugPy(PythonToolBase):
     default_lockfile_path = "src/python/pants/backend/python/subsystems/debugpy.lock"
     default_lockfile_url = git_url(default_lockfile_path)
 
+    args = ArgsListOption(example="--log-to-stderr")
+
+    @staticmethod
+    def _get_main_spec_args(main: MainSpecification) -> tuple[str, ...]:
+        if isinstance(main, EntryPoint):
+            if main.function:
+                return ("-c", f"import {main.module};{main.module}.{main.function}();")
+            return ("-m", main.module)
+
+        assert isinstance(main, ConsoleScript)
+        # NB: This is only necessary while debugpy supports Py 3.7, as `importlib.metadata` was
+        # added in Py 3.8 and would allow us to resolve the console_script using just the stdlib.
+        return (
+            "-c",
+            (
+                "from pex.third_party.pkg_resources import working_set;"
+                + f"(next(working_set.iter_entry_points('console_scripts', '{main.name}')).resolve())()"
+            ),
+        )
+
+    def get_args(
+        self, debug_adapter: DebugAdapterSubsystem, main: MainSpecification
+    ) -> tuple[str, ...]:
+        return (
+            "--listen",
+            f"{debug_adapter.host}:{debug_adapter.port}",
+            "--wait-for-client",
+            *self.args,
+            *self._get_main_spec_args(main),
+        )
+
 
 class DebugPyLockfileSentinel(GenerateToolLockfileSentinel):
     resolve_name = DebugPy.options_scope