Better error handling for missing setuptools. (#471)

This helped reveal the cause of #470

.travis.yml

@@ -12,7 +12,7 @@ env:
   global:
     # This is necessary to have consistent testing of methods that rely on falling back to PATH for
     # selecting a python interpreter.
-    - PATH=$PATH:$PWD/.tox/py36/bin:$PWD/.tox/py27/bin
+    - PATH=$PWD/.tox/py36/bin:$PWD/.tox/py27/bin:$PATH
 
 cache:
   directories:
@@ -73,7 +73,7 @@ matrix:
       env: TOXENV=pypy
 
 install:
-  - pip install -U tox
+  - pip install -U tox "setuptools<34"
 
 script:
   - tox -v

pex/pex_builder.py

@@ -403,12 +403,17 @@ def _prepare_bootstrap(self):
     # self-contained.
 
     wrote_setuptools = False
-    setuptools = DistributionHelper.distribution_from_path(
-        self._interpreter.get_location('setuptools'),
-        name='setuptools')
+    setuptools_location = self._interpreter.get_location('setuptools')
+    if setuptools_location is None:
+      raise RuntimeError(
+        'Failed to find setuptools via %s while building pex!' % self._interpreter.binary
+      )
 
+    setuptools = DistributionHelper.distribution_from_path(setuptools_location, name='setuptools')
     if setuptools is None:
-      raise RuntimeError('Failed to find setuptools while building pex!')
+      raise RuntimeError(
+        'Failed to find setuptools via %s while building pex!' % self._interpreter.binary
+      )
 
     for fn, content_stream in DistributionHelper.walk_data(setuptools):
       if fn.startswith('pkg_resources') or fn.startswith('_markerlib'):

pex/testing.py

@@ -18,6 +18,7 @@
 from .installer import EggInstaller, Packager
 from .pex_builder import PEXBuilder
 from .util import DistributionHelper, named_temporary_file
+from .version import SETUPTOOLS_REQUIREMENT
 
 
 @contextlib.contextmanager
@@ -209,7 +210,6 @@ class IntegResults(namedtuple('results', 'output return_code exception traceback
 
   def assert_success(self):
     if not (self.exception is None and self.return_code is None):
-      print(self.traceback)
       raise AssertionError('integration test failed: return_code=%s, exception=%r, traceback=%s' % (
         self.return_code, self.exception, self.traceback
       ))
@@ -289,12 +289,12 @@ def combine_pex_coverage(coverage_file_iter):
   return combined.filename
 
 
-def bootstrap_python_installer(install_location):
-  safe_rmtree(install_location)
+def bootstrap_python_installer(dest):
+  safe_rmtree(dest)
   for _ in range(3):
     try:
       subprocess.check_call(
-        ['git', 'clone', 'https://github.com/pyenv/pyenv.git', install_location]
+        ['git', 'clone', 'https://github.com/pyenv/pyenv.git', dest]
       )
     except subprocess.CalledProcessError as e:
       print('caught exception: %r' % e)
@@ -307,13 +307,16 @@ def bootstrap_python_installer(install_location):
 
 def ensure_python_interpreter(version):
   pyenv_root = os.path.join(os.getcwd(), '.pyenv_test')
-  installer_path = os.path.join(pyenv_root, 'bin', 'pyenv')
-  if not os.path.exists(installer_path):
+  interpreter_location = os.path.join(pyenv_root, 'versions', version)
+  pyenv = os.path.join(pyenv_root, 'bin', 'pyenv')
+  pip = os.path.join(interpreter_location, 'bin', 'pip')
+
+  if not os.path.exists(pyenv):
     bootstrap_python_installer(pyenv_root)
 
-  install_location = os.path.join(pyenv_root, 'versions', version)
-  if not os.path.exists(install_location):
+  if not os.path.exists(interpreter_location):
     os.environ['PYENV_ROOT'] = pyenv_root
-    subprocess.call([installer_path, 'install', version])
+    subprocess.call([pyenv, 'install', version])
+    subprocess.call([pip, 'install', SETUPTOOLS_REQUIREMENT])
 
-  return os.path.join(install_location, 'bin', 'python' + version[0:3])
+  return os.path.join(interpreter_location, 'bin', 'python' + version[0:3])

tox.ini

@@ -17,6 +17,7 @@ deps =
     twitter.common.testing>=0.3.1,<0.4.0
     wheel==0.29.0
     packaging==16.8
+    setuptools<34.0
     py27: mock
     pypy: mock
     run: requests