Fixup PEXEnvironment extras resolution. (#617)

In #582 and #592 support for environment markers was added to the pex
runtime. In so doing, the resolver was fixed to record full requirement
strings into PEX-INFO. Since part of those full requirement strings
could now include environment markers that selected for active extras,
a bug was introduced since we did not also add the active extras to the
environment marker evaluation environment.

This change adds a failing test that is fixed by properly setting up the
environment marker environment to include active extras.

Fixes #615.

pex/environment.py

@@ -159,10 +159,13 @@ def _resolve(self, working_set, reqs):
     unresolved_reqs = set()
     resolveds = set()
 
+    environment = self._target_interpreter_env.copy()
+    environment['extra'] = list(set(itertools.chain(*(req.extras for req in reqs))))
+
     # Resolve them one at a time so that we can figure out which ones we need to elide should
     # there be an interpreter incompatibility.
     for req in reqs:
-      if req.marker and not req.marker.evaluate(environment=self._target_interpreter_env):
+      if req.marker and not req.marker.evaluate(environment=environment):
         TRACER.log('Skipping activation of `%s` due to environment marker de-selection' % req)
         continue
       with TRACER.timed('Resolving %s' % req, V=2):

tests/test_environment.py

@@ -163,3 +163,24 @@ def bad_interpreter(include_site_extras=True):
       release, _, _ = platform.mac_ver()
       major_minor = '.'.join(release.split('.')[:2])
       assert to_bytes('macosx-{}-intel'.format(major_minor)) == stdout.strip()
+
+
+def test_activate_extras_issue_615():
+  with yield_pex_builder() as pb:
+    for resolved_dist in resolver.resolve(['pex[requests]==1.5.1']):
+      pb.add_requirement(resolved_dist.requirement)
+      pb.add_dist_location(resolved_dist.distribution.location)
+    pb.set_script('pex')
+    pb.freeze()
+    env = os.environ.copy()
+    env['PEX_VERBOSE'] = '9'
+    process = PEX(pb.path()).run(args=['--version'],
+                                 env=env,
+                                 blocking=False,
+                                 stdout=subprocess.PIPE,
+                                 stderr=subprocess.PIPE)
+    stdout, stderr = process.communicate()
+    assert 0 == process.returncode, (
+      'Process failed with exit code {} and stderr:\n{}'.format(process.returncode, stderr)
+    )
+    assert to_bytes('{} 1.5.1'.format(os.path.basename(pb.path()))) == stdout.strip()