V2 ./pants test.pytest selects interpreter based off of compatibility constraints

src/python/pants/backend/python/rules/python_test_runner.py

@@ -4,12 +4,14 @@
 
 from __future__ import absolute_import, division, print_function, unicode_literals
 
+import os
 import sys
 from builtins import str
 
 from future.utils import text_type
 
 from pants.backend.python.subsystems.pytest import PyTest
+from pants.backend.python.subsystems.python_setup import PythonSetup
 from pants.engine.fs import Digest, MergedDirectories, Snapshot, UrlToFetch
 from pants.engine.isolated_process import (ExecuteProcessRequest, ExecuteProcessResult,
                                            FallibleExecuteProcessResult)
@@ -26,10 +28,24 @@ class PyTestResult(TestResult):
   pass
 
 
+def parse_interpreter_constraints(python_setup, python_target_adaptors):
+  constraints = {
+    constraint
+    for target_adaptor in python_target_adaptors
+    for constraint in python_setup.compatibility_or_constraints(
+      getattr(target_adaptor, 'compatibility', None)
+    )
+  }
+  constraints_args = []
+  for constraint in sorted(constraints):
+    constraints_args.extend(["--interpreter-constraint", constraint])
+  return constraints_args
+
+
 # TODO: Support deps
 # TODO: Support resources
-@rule(PyTestResult, [TransitiveHydratedTarget, PyTest])
-def run_python_test(transitive_hydrated_target, pytest):
+@rule(PyTestResult, [TransitiveHydratedTarget, PyTest, PythonSetup])
+def run_python_test(transitive_hydrated_target, pytest, python_setup):
   target_root = transitive_hydrated_target.root
 
   # TODO: Inject versions and digests here through some option, rather than hard-coding it.
@@ -50,30 +66,31 @@ def run_python_test(transitive_hydrated_target, pytest):
       for py_req in maybe_python_req_lib.adaptor.requirements:
         all_requirements.append(str(py_req.requirement))
 
-  # TODO: This should be configurable, both with interpreter constraints, and for remote execution.
   # TODO(#7061): This str() can be removed after we drop py2!
   python_binary = text_type(sys.executable)
+  interpreter_constraint_args = parse_interpreter_constraints(
+    python_setup, python_target_adaptors=[target.adaptor for target in all_targets]
+  )
 
   # TODO: This is non-hermetic because the requirements will be resolved on the fly by
   # pex27, where it should be hermetically provided in some way.
   output_pytest_requirements_pex_filename = 'pytest-with-requirements.pex'
   requirements_pex_argv = [
     python_binary,
     './{}'.format(pex_snapshot.files[0]),
-    # TODO(#7061): This text_type() can be removed after we drop py2!
-    '--python', text_type(python_binary),
     '-e', 'pytest:main',
     '-o', output_pytest_requirements_pex_filename,
-    # Sort all user requirement strings to increase the chance of cache hits across invocations.
-  ] + [
+  ] + interpreter_constraint_args + [
     # TODO(#7061): This text_type() wrapping can be removed after we drop py2!
     text_type(req)
+    # Sort all user requirement strings to increase the chance of cache hits across invocations.
     for req in sorted(
         list(pytest.get_requirement_strings())
         + list(all_requirements))
   ]
   requirements_pex_request = ExecuteProcessRequest(
     argv=tuple(requirements_pex_argv),
+    env={'PATH': os.pathsep.join(python_setup.interpreter_search_paths)},
     input_files=pex_snapshot.directory_digest,
     description='Resolve requirements for {}'.format(target_root.address.reference()),
     output_files=(output_pytest_requirements_pex_filename,),
@@ -101,6 +118,7 @@ def run_python_test(transitive_hydrated_target, pytest):
 
   request = ExecuteProcessRequest(
     argv=(python_binary, './{}'.format(output_pytest_requirements_pex_filename)),
+    env={'PATH': os.pathsep.join(python_setup.interpreter_search_paths)},
     input_files=merged_input_files,
     description='Run pytest for {}'.format(target_root.address.reference()),
   )
@@ -116,4 +134,5 @@ def rules():
   return [
       run_python_test,
       optionable_rule(PyTest),
+      optionable_rule(PythonSetup),
     ]

tests/python/pants_test/backend/python/rules/BUILD

@@ -0,0 +1,13 @@
+# Copyright 2019 Pants project contributors (see CONTRIBUTORS.md).
+# Licensed under the Apache License, Version 2.0 (see LICENSE).
+
+python_tests(
+  name='python_test_runner',
+  sources=['test_python_test_runner.py'],
+  dependencies=[
+    'src/python/pants/backend/python/rules',
+    'src/python/pants/backend/python/subsystems',
+    'src/python/pants/engine/legacy:structs',
+    'tests/python/pants_test/subsystem:subsystem_utils',
+  ]
+)

tests/python/pants_test/backend/python/rules/test_python_test_runner.py

@@ -0,0 +1,31 @@
+# coding=utf-8
+# Copyright 2019 Pants project contributors (see CONTRIBUTORS.md).
+# Licensed under the Apache License, Version 2.0 (see LICENSE).
+
+from __future__ import absolute_import, division, print_function, unicode_literals
+
+from unittest import TestCase
+
+from pants.backend.python.rules.python_test_runner import parse_interpreter_constraints
+from pants.backend.python.subsystems.python_setup import PythonSetup
+from pants.engine.legacy.structs import PythonTargetAdaptor
+from pants_test.subsystem.subsystem_util import global_subsystem_instance
+
+
+class TestPythonTestRunner(TestCase):
+
+  def test_interpreter_constraints_parsing(self):
+    python_setup = global_subsystem_instance(PythonSetup)
+    target_adaptors = [
+      # NB: This target will use the global --python-setup-interpreter-constraints.
+      PythonTargetAdaptor(compatibility=None),
+      PythonTargetAdaptor(compatibility=["CPython>=400"]),
+    ]
+    self.assertEqual(
+      parse_interpreter_constraints(python_setup, target_adaptors),
+      [
+        "--interpreter-constraint", "CPython>=2.7,<3",
+        "--interpreter-constraint", "CPython>=3.6,<4",
+        "--interpreter-constraint", "CPython>=400"
+      ]
+    )