Minimize interpreter bootstrapping in tests. (#571)

Master is currently timing out trying to fetch and build 7 interpreters.
Since We have no need for seven, constrain the interpreter count. Along
the way fix a flaky test that exposed production code not setting up all
interpreters.

pex/bin/pex.py

@@ -557,19 +557,7 @@ def installer_provider(sdist):
     return interpreter.with_extra(egg.name, egg.raw_version, egg.path)
 
 
-def get_interpreter(python_interpreter, interpreter_cache_dir, repos, use_wheel):
-  interpreter = None
-
-  if python_interpreter:
-    if os.path.exists(python_interpreter):
-      interpreter = PythonInterpreter.from_binary(python_interpreter)
-    else:
-      interpreter = PythonInterpreter.from_env(python_interpreter)
-    if interpreter is None:
-      die('Failed to find interpreter: %s' % python_interpreter)
-  else:
-    interpreter = PythonInterpreter.get()
-
+def setup_interpreter(interpreter, interpreter_cache_dir, repos, use_wheel):
   with TRACER.timed('Setting up interpreter %s' % interpreter.binary, V=2):
     resolve = functools.partial(resolve_interpreter, interpreter_cache_dir, repos)
 
@@ -585,13 +573,16 @@ def get_interpreter(python_interpreter, interpreter_cache_dir, repos, use_wheel)
 
 def build_pex(args, options, resolver_option_builder):
   with TRACER.timed('Resolving interpreters', V=2):
-    interpreters = [
-      get_interpreter(interpreter,
-                      options.interpreter_cache_dir,
-                      options.repos,
-                      options.use_wheel)
-      for interpreter in options.python or [None]
-    ]
+    def to_python_interpreter(full_path_or_basename):
+      if os.path.exists(full_path_or_basename):
+        return PythonInterpreter.from_binary(full_path_or_basename)
+      else:
+        interpreter = PythonInterpreter.from_env(full_path_or_basename)
+        if interpreter is None:
+          die('Failed to find interpreter: %s' % full_path_or_basename)
+        return interpreter
+
+    interpreters = [to_python_interpreter(interp) for interp in options.python or [sys.executable]]
 
   if options.interpreter_constraint:
     # NB: options.python and interpreter constraints cannot be used together, so this will not
@@ -602,7 +593,13 @@ def build_pex(args, options, resolver_option_builder):
     pex_python_path = rc_variables.get('PEX_PYTHON_PATH', '')
     interpreters = find_compatible_interpreters(pex_python_path, constraints)
 
-  if not interpreters:
+  setup_interpreters = [setup_interpreter(interp,
+                                          options.interpreter_cache_dir,
+                                          options.repos,
+                                          options.use_wheel)
+                        for interp in interpreters]
+
+  if not setup_interpreters:
     die('Could not find compatible interpreter', CANNOT_SETUP_INTERPRETER)
 
   try:
@@ -612,7 +609,7 @@ def build_pex(args, options, resolver_option_builder):
     # options.preamble_file is None
     preamble = None
 
-  interpreter = min(interpreters)
+  interpreter = min(setup_interpreters)
 
   pex_builder = PEXBuilder(path=safe_mkdtemp(), interpreter=interpreter, preamble=preamble)
 

pex/testing.py

@@ -323,7 +323,21 @@ def bootstrap_python_installer(dest):
     raise RuntimeError("Helper method could not clone pyenv from git after 3 tries")
 
 
+# NB: We keep the pool of bootstrapped interpreters as small as possible to avoid timeouts in CI
+# otherwise encountered when fetching and building too many on a cache miss. In the past we had
+# issues with the combination of 7 total unique interpreter versions and a Travis-CI timeout of 50
+# minutes for a shard.
+PY27 = '2.7.15'
+PY35 = '3.5.6'
+PY36 = '3.6.6'
+
+_VERSIONS = (PY27, PY35, PY36)
+
+
 def ensure_python_distribution(version):
+  if version not in _VERSIONS:
+    raise ValueError('Please constrain version to one of {}'.format(_VERSIONS))
+
   pyenv_root = os.path.join(os.getcwd(), '.pyenv_test')
   interpreter_location = os.path.join(pyenv_root, 'versions', version)
   pyenv = os.path.join(pyenv_root, 'bin', 'pyenv')

tests/test_installer.py

@@ -5,9 +5,10 @@
 
 import pytest
 
-from pex.bin.pex import get_interpreter
+from pex.bin.pex import setup_interpreter
 from pex.installer import WheelInstaller
-from pex.testing import ensure_python_interpreter, make_installer, temporary_dir
+from pex.interpreter import PythonInterpreter
+from pex.testing import PY36, ensure_python_interpreter, make_installer, temporary_dir
 from pex.version import SETUPTOOLS_REQUIREMENT, WHEEL_REQUIREMENT
 
 
@@ -23,8 +24,8 @@ def mixins(self):
 @contextlib.contextmanager
 def bare_interpreter():
   with temporary_dir() as interpreter_cache:
-    yield get_interpreter(
-      python_interpreter=ensure_python_interpreter('3.6.3'),
+    yield setup_interpreter(
+      interpreter=PythonInterpreter.from_binary(ensure_python_interpreter(PY36)),
       interpreter_cache_dir=interpreter_cache,
       repos=None,
       use_wheel=True

tests/test_integration.py

@@ -22,6 +22,8 @@
     NOT_CPYTHON27_OR_OSX,
     NOT_CPYTHON36,
     NOT_CPYTHON36_OR_LINUX,
+    PY27,
+    PY36,
     ensure_python_interpreter,
     get_dep_dist_names_from_pex,
     run_pex_command,
@@ -354,7 +356,7 @@ def test_interpreter_constraints_to_pex_info_py2():
 
 @pytest.mark.skipif(IS_PYPY)
 def test_interpreter_constraints_to_pex_info_py3():
-  py3_interpreter = ensure_python_interpreter('3.6.3')
+  py3_interpreter = ensure_python_interpreter(PY36)
   with environment_as(PATH=os.path.dirname(py3_interpreter)):
     with temporary_dir() as output_dir:
       # target python 3
@@ -387,8 +389,8 @@ def test_interpreter_resolution_with_pex_python_path():
     with open(pexrc_path, 'w') as pexrc:
       # set pex python path
       pex_python_path = ':'.join([
-        ensure_python_interpreter('2.7.10'),
-        ensure_python_interpreter('3.6.3')
+        ensure_python_interpreter(PY27),
+        ensure_python_interpreter(PY36)
       ])
       pexrc.write("PEX_PYTHON_PATH=%s" % pex_python_path)
 
@@ -422,8 +424,8 @@ def test_interpreter_resolution_pex_python_path_precedence_over_pex_python():
     with open(pexrc_path, 'w') as pexrc:
       # set both PPP and PP
       pex_python_path = ':'.join([
-        ensure_python_interpreter('2.7.10'),
-        ensure_python_interpreter('3.6.3')
+        ensure_python_interpreter(PY27),
+        ensure_python_interpreter(PY36)
       ])
       pexrc.write("PEX_PYTHON_PATH=%s\n" % pex_python_path)
       pex_python = '/path/to/some/python'
@@ -464,8 +466,8 @@ def test_pex_exec_with_pex_python_path_only():
     with open(pexrc_path, 'w') as pexrc:
       # set pex python path
       pex_python_path = ':'.join([
-        ensure_python_interpreter('2.7.10'),
-        ensure_python_interpreter('3.6.3')
+        ensure_python_interpreter(PY27),
+        ensure_python_interpreter(PY36)
       ])
       pexrc.write("PEX_PYTHON_PATH=%s" % pex_python_path)
 
@@ -490,8 +492,8 @@ def test_pex_exec_with_pex_python_path_and_pex_python_but_no_constraints():
     with open(pexrc_path, 'w') as pexrc:
       # set both PPP and PP
       pex_python_path = ':'.join([
-        ensure_python_interpreter('2.7.10'),
-        ensure_python_interpreter('3.6.3')
+        ensure_python_interpreter(PY27),
+        ensure_python_interpreter(PY36)
       ])
       pexrc.write("PEX_PYTHON_PATH=%s\n" % pex_python_path)
       pex_python = '/path/to/some/python'
@@ -513,14 +515,14 @@ def test_pex_exec_with_pex_python_path_and_pex_python_but_no_constraints():
 
 @pytest.mark.skipif(IS_PYPY)
 def test_pex_python():
-  py2_path_interpreter = ensure_python_interpreter('2.7.10')
-  py3_path_interpreter = ensure_python_interpreter('3.6.3')
+  py2_path_interpreter = ensure_python_interpreter(PY27)
+  py3_path_interpreter = ensure_python_interpreter(PY36)
   path = ':'.join([os.path.dirname(py2_path_interpreter), os.path.dirname(py3_path_interpreter)])
   with environment_as(PATH=path):
     with temporary_dir() as td:
       pexrc_path = os.path.join(td, '.pexrc')
       with open(pexrc_path, 'w') as pexrc:
-        pex_python = ensure_python_interpreter('3.6.3')
+        pex_python = ensure_python_interpreter(PY36)
         pexrc.write("PEX_PYTHON=%s" % pex_python)
 
       # test PEX_PYTHON with valid constraints
@@ -541,7 +543,7 @@ def test_pex_python():
       # test PEX_PYTHON with incompatible constraints
       pexrc_path = os.path.join(td, '.pexrc')
       with open(pexrc_path, 'w') as pexrc:
-        pex_python = ensure_python_interpreter('2.7.10')
+        pex_python = ensure_python_interpreter(PY27)
         pexrc.write("PEX_PYTHON=%s" % pex_python)
 
       pex_out_path = os.path.join(td, 'pex2.pex')
@@ -578,7 +580,7 @@ def test_entry_point_targeting():
   with temporary_dir() as td:
     pexrc_path = os.path.join(td, '.pexrc')
     with open(pexrc_path, 'w') as pexrc:
-      pex_python = ensure_python_interpreter('3.6.3')
+      pex_python = ensure_python_interpreter(PY36)
       pexrc.write("PEX_PYTHON=%s" % pex_python)
 
     # test pex with entry point
@@ -609,9 +611,9 @@ def test_interpreter_selection_using_os_environ_for_bootstrap_reexec():
     # execute with. The child interpreter is the interpreter we expect the
     # child pex to execute with.
     if (sys.version_info[0], sys.version_info[1]) == (3, 6):
-      child_pex_interpreter_version = '3.6.3'
+      child_pex_interpreter_version = PY36
     else:
-      child_pex_interpreter_version = '2.7.10'
+      child_pex_interpreter_version = PY27
 
     # Write parent pex's pexrc.
     with open(pexrc_path, 'w') as pexrc:
@@ -993,7 +995,7 @@ def test_invalid_entry_point_verification_3rdparty():
 def test_multiplatform_entrypoint():
   with temporary_dir() as td:
     pex_out_path = os.path.join(td, 'p537.pex')
-    interpreter = ensure_python_interpreter('3.6.3')
+    interpreter = ensure_python_interpreter(PY36)
     res = run_pex_command(['p537==1.0.3',
                            '--no-build',
                            '--python={}'.format(interpreter),

tests/test_interpreter.py

@@ -7,8 +7,11 @@
 import pytest
 
 from pex import interpreter
+from pex.compatibility import PY3
 from pex.testing import (
     IS_PYPY,
+    PY27,
+    PY35,
     ensure_python_distribution,
     ensure_python_interpreter,
     temporary_dir
@@ -20,24 +23,26 @@
   from unittest.mock import patch
 
 
-def version_from_tuple(version_tuple):
-  return '.'.join(str(x) for x in version_tuple)
+def tuple_from_version(version_string):
+  return tuple(int(component) for component in version_string.split('.'))
 
 
 class TestPythonInterpreter(object):
 
-  @pytest.mark.skipif('sys.version_info >= (3,0)')
+  @pytest.mark.skipif(PY3,
+                      reason='This test relies on the `reload` builtin which is not available in '
+                             'python 3 as a builtin.')
   def test_all_does_not_raise_with_empty_path_envvar(self):
     """ additionally, tests that the module does not raise at import """
     with patch.dict(os.environ, clear=True):
       reload(interpreter)
       interpreter.PythonInterpreter.all()
 
-  TEST_INTERPRETER1_VERSION_TUPLE = (2, 7, 10)
-  TEST_INTERPRETER1_VERSION = version_from_tuple(TEST_INTERPRETER1_VERSION_TUPLE)
+  TEST_INTERPRETER1_VERSION = PY27
+  TEST_INTERPRETER1_VERSION_TUPLE = tuple_from_version(TEST_INTERPRETER1_VERSION)
 
-  TEST_INTERPRETER2_VERSION_TUPLE = (2, 7, 9)
-  TEST_INTERPRETER2_VERSION = version_from_tuple(TEST_INTERPRETER2_VERSION_TUPLE)
+  TEST_INTERPRETER2_VERSION = PY35
+  TEST_INTERPRETER2_VERSION_TUPLE = tuple_from_version(TEST_INTERPRETER2_VERSION)
 
   @pytest.fixture
   def test_interpreter1(self):

tests/test_pex.py

@@ -11,7 +11,7 @@
 import pytest
 from twitter.common.contextutil import temporary_file
 
-from pex.bin.pex import get_interpreter
+from pex.bin.pex import setup_interpreter
 from pex.compatibility import PY2, WINDOWS, nested, to_bytes
 from pex.installer import EggInstaller, WheelInstaller
 from pex.interpreter import PythonInterpreter
@@ -21,6 +21,8 @@
 from pex.resolver import resolve
 from pex.testing import (
     IS_PYPY,
+    PY27,
+    PY36,
     ensure_python_interpreter,
     make_bdist,
     make_installer,
@@ -322,9 +324,9 @@ def test_pex_verify_entry_point_module_should_fail():
 @pytest.mark.skipif(IS_PYPY)
 def test_activate_interpreter_different_from_current():
   with temporary_dir() as pex_root:
-    interp_version = '3.6.3' if PY2 else '2.7.10'
-    custom_interpreter = get_interpreter(
-      python_interpreter=ensure_python_interpreter(interp_version),
+    interp_version = PY36 if PY2 else PY27
+    custom_interpreter = setup_interpreter(
+      interpreter=PythonInterpreter.from_binary(ensure_python_interpreter(interp_version)),
       interpreter_cache_dir=os.path.join(pex_root, 'interpreters'),
       repos=None,  # Default to PyPI.
       use_wheel=True

tests/test_pex_bootstrapper.py

@@ -9,7 +9,7 @@
 from pex.common import open_zip
 from pex.interpreter import PythonInterpreter
 from pex.pex_bootstrapper import find_compatible_interpreters, get_pex_info
-from pex.testing import IS_PYPY, ensure_python_interpreter, write_simple_pex
+from pex.testing import IS_PYPY, PY27, PY35, PY36, ensure_python_interpreter, write_simple_pex
 
 
 def test_get_pex_info():
@@ -34,39 +34,25 @@ def test_get_pex_info():
 
 @pytest.mark.skipif(IS_PYPY)
 def test_find_compatible_interpreters():
-  pex_python_path = ':'.join([
-    ensure_python_interpreter('2.7.9'),
-    ensure_python_interpreter('2.7.10'),
-    ensure_python_interpreter('2.7.11'),
-    ensure_python_interpreter('3.4.2'),
-    ensure_python_interpreter('3.5.4'),
-    ensure_python_interpreter('3.6.2'),
-    ensure_python_interpreter('3.6.3')
-  ])
+  py27 = ensure_python_interpreter(PY27)
+  py35 = ensure_python_interpreter(PY35)
+  py36 = ensure_python_interpreter(PY36)
+  pex_python_path = ':'.join([py27, py35, py36])
 
-  interpreters = find_compatible_interpreters(pex_python_path, ['>3'])
-  assert interpreters[0].binary == pex_python_path.split(':')[3]  # 3.4.2
+  def find_interpreters(*constraints):
+    return [interp.binary for interp in find_compatible_interpreters(pex_python_path, constraints)]
 
-  interpreters = find_compatible_interpreters(pex_python_path, ['<3'])
-  assert interpreters[0].binary == pex_python_path.split(':')[0]  # 2.7.9
+  assert [py35, py36] == find_interpreters('>3')
+  assert [py27] == find_interpreters('<3')
 
-  interpreters = find_compatible_interpreters(pex_python_path, ['>3.5.4'])
-  assert interpreters[0].binary == pex_python_path.split(':')[5]  # 3.6.2
+  assert [py36] == find_interpreters('>{}'.format(PY35))
+  assert [py35] == find_interpreters('>{}, <{}'.format(PY27, PY36))
+  assert [py36] == find_interpreters('>=3.6')
 
-  interpreters = find_compatible_interpreters(pex_python_path, ['>3.4.2, <3.6'])
-  assert interpreters[0].binary == pex_python_path.split(':')[4]  # 3.5.4
+  assert [] == find_interpreters('<2')
+  assert [] == find_interpreters('>4')
+  assert [] == find_interpreters('>{}, <{}'.format(PY27, PY35))
 
-  interpreters = find_compatible_interpreters(pex_python_path, ['>3.6.2'])
-  assert interpreters[0].binary == pex_python_path.split(':')[6]  # 3.6.3
-
-  interpreters = find_compatible_interpreters(pex_python_path, ['<2'])
-  assert not interpreters
-
-  interpreters = find_compatible_interpreters(pex_python_path, ['>4'])
-  assert not interpreters
-
-  interpreters = find_compatible_interpreters(pex_python_path, ['<2.7.11, >2.7.9'])
-  assert interpreters[0].binary == pex_python_path.split(':')[1]  # 2.7.10
-
-  interpreters = find_compatible_interpreters('', ['<3'])
-  assert interpreters[0] in PythonInterpreter.all()  # All interpreters on PATH
+  # All interpreters on PATH.
+  interpreters = find_compatible_interpreters(pex_python_path='', compatibility_constraints=['<3'])
+  assert set(interpreters).issubset(set(PythonInterpreter.all()))