Make running individual Python tests less painful

Before this change, running Python tests individually required
building a tox environment via the run_tests script and then specifying
long environment variables to filter out just the test we wanted to run
(and then we wouldn't be able to get the output on interrupt, nor would
we have an easy way of determining the PID of the process for debugger
attachment). Now invoking the build_python.sh script creates a workable
python virtual environment that includes all necessary libraries and
tests (s.t. running a single test is now possible by just knowing the
module name). This does not change existing supported means of running
tests (e.g. through run_tests.py).

An additional way of running individual tests has been introduced.
Following invocation of `./tools/run_tests/build_python.sh` (or
run_tests.py), one may invoke

  ./$VENV/bin/python -m $TEST_MODULE_NAME

and acquire a single running process that *is* the test process (rather
than a parent of the process). $VENV is the virtual environment name
specified to `build_python.sh` (defaults to `py27`) and
$TEST_MODULE_NAME is what it says on the tin.

6 files changed, 114 insertions, 51 deletions

diff --git a/PYTHON-MANIFEST.in b/PYTHON-MANIFEST.in
index 3ebba6ec3f..635e77b875 100644
--- a/PYTHON-MANIFEST.in
+++ b/PYTHON-MANIFEST.in
@@ -1,6 +1,5 @@
 recursive-include src/python/grpcio/grpc *.c *.h *.py *.pyx *.pxd *.pxi *.python *.pem
 recursive-exclude src/python/grpcio/grpc/_cython *.so *.pyd
-graft src/python/grpcio/tests
 graft src/python/grpcio/grpcio.egg-info
 graft src/core
 graft src/boringssl
diff --git a/tools/run_tests/build_python.sh b/tools/run_tests/build_python.sh
index 3b1c7d2d40..9d2813fa19 100755
--- a/tools/run_tests/build_python.sh
+++ b/tools/run_tests/build_python.sh
@@ -33,25 +33,70 @@ set -ex
 # change to grpc repo root
 cd $(dirname $0)/../..
 
-TOX_PYTHON_ENV="$1"
-PY_VERSION="${TOX_PYTHON_ENV: -2}"
+PYTHON=${1:-python2.7}
+VENV=${2:-py27}
+VENV_RELATIVE_PYTHON=${3:-bin/python}
+TOOLCHAIN=${4:-unix}
 
 ROOT=`pwd`
 export CFLAGS="-I$ROOT/include -std=gnu99 -fno-wrapv"
 export GRPC_PYTHON_BUILD_WITH_CYTHON=1
 
-if [ "$CONFIG" = "gcov" ]
-then
+# If ccache is available, use it... unless we're on Mac, then all hell breaks
+# loose because Python does hacky things to support other hacky things done to
+# hacky things on Mac OS X
+PLATFORM=`uname -s`
+if [ "${PLATFORM/Darwin}" = "$PLATFORM" ]; then
+  # We're not on Darwin (Mac OS X)
+  if [ -x "$(command -v ccache)" ]; then
+    if [ -x "$(command -v gcc)" ]; then
+      export CC='ccache gcc'
+    elif [ -x "$(command -v clang)" ]; then
+      export CC='ccache clang'
+    fi
+  fi
+fi
+
+# Find `realpath`
+if [ -x "$(command -v realpath)" ]; then
+  export REALPATH=realpath
+elif [ -x "$(command -v grealpath)" ]; then
+  export REALPATH=grealpath
+else
+  echo 'Couldn'"'"'t find `realpath` or `grealpath`'
+  exit 1
+fi
+
+if [ "$CONFIG" = "gcov" ]; then
   export GRPC_PYTHON_ENABLE_CYTHON_TRACING=1
 fi
 
-tox -e ${TOX_PYTHON_ENV} --notest
+($PYTHON -m virtualenv $VENV || true)
+VENV_PYTHON=`$REALPATH -s "$VENV/$VENV_RELATIVE_PYTHON"`
+
+# pip-installs the directory specified. Used because on MSYS the vanilla Windows
+# Python gets confused when parsing paths.
+pip_install_dir() {
+  PWD=`pwd`
+  cd $1
+  ($VENV_PYTHON setup.py build_ext -c $TOOLCHAIN || true)
+  # install the dependencies
+  $VENV_PYTHON -m pip install --upgrade .
+  # ensure that we've reinstalled the test packages
+  $VENV_PYTHON -m pip install --upgrade --force-reinstall --no-deps .
+  cd $PWD
+}
 
-$ROOT/.tox/${TOX_PYTHON_ENV}/bin/pip install cython
-$ROOT/.tox/${TOX_PYTHON_ENV}/bin/pip install $ROOT
-$ROOT/.tox/${TOX_PYTHON_ENV}/bin/python $ROOT/tools/distrib/python/make_grpcio_tools.py
-$ROOT/.tox/${TOX_PYTHON_ENV}/bin/pip install $ROOT/tools/distrib/python/grpcio_tools
-$ROOT/.tox/${TOX_PYTHON_ENV}/bin/python $ROOT/src/python/grpcio_health_checking/setup.py preprocess
-$ROOT/.tox/${TOX_PYTHON_ENV}/bin/pip install $ROOT/src/python/grpcio_health_checking
-$ROOT/.tox/${TOX_PYTHON_ENV}/bin/python $ROOT/src/python/grpcio_tests/setup.py preprocess
-$ROOT/.tox/${TOX_PYTHON_ENV}/bin/python $ROOT/src/python/grpcio_tests/setup.py build_proto_modules
+$VENV_PYTHON -m pip install --upgrade pip setuptools
+$VENV_PYTHON -m pip install cython
+pip_install_dir $ROOT
+$VENV_PYTHON $ROOT/tools/distrib/python/make_grpcio_tools.py
+pip_install_dir $ROOT/tools/distrib/python/grpcio_tools
+# TODO(atash) figure out namespace packages and grpcio-tools and auditwheel
+# etc...
+pip_install_dir $ROOT
+$VENV_PYTHON $ROOT/src/python/grpcio_health_checking/setup.py preprocess
+pip_install_dir $ROOT/src/python/grpcio_health_checking
+$VENV_PYTHON $ROOT/src/python/grpcio_tests/setup.py preprocess
+$VENV_PYTHON $ROOT/src/python/grpcio_tests/setup.py build_proto_modules
+pip_install_dir $ROOT/src/python/grpcio_tests
diff --git a/tools/run_tests/performance/run_worker_python.sh b/tools/run_tests/performance/run_worker_python.sh
index 2bca5e1695..3b8ba6f4e4 100755
--- a/tools/run_tests/performance/run_worker_python.sh
+++ b/tools/run_tests/performance/run_worker_python.sh
@@ -32,4 +32,4 @@ set -ex
 
 cd $(dirname $0)/../../..
 
-PYTHONPATH=src/python/grpcio_tests:src/python/grpcio:src/python/gens .tox/py27/bin/python src/python/grpcio_tests/tests/qps/qps_worker.py $@
+PYTHONPATH=src/python/grpcio_tests:src/python/grpcio:src/python/gens py27/bin/python src/python/grpcio_tests/tests/qps/qps_worker.py $@
diff --git a/tools/run_tests/run_interop_tests.py b/tools/run_tests/run_interop_tests.py
index adf9adaf13..13a4a49325 100755
--- a/tools/run_tests/run_interop_tests.py
+++ b/tools/run_tests/run_interop_tests.py
@@ -304,8 +304,11 @@ class PythonLanguage:
 
   def client_cmd(self, args):
     return [
-        'tox -einterop_client --',
-        ' '.join(args)
+        'py27/bin/python',
+        'src/python/grpcio_tests/setup.py',
+        'run_interop',
+        '--client',
+        '--args="{}"'.format(' '.join(args))
     ]
 
   def cloud_to_prod_env(self):
@@ -313,8 +316,11 @@ class PythonLanguage:
 
   def server_cmd(self, args):
     return [
-        'tox -einterop_server --',
-        ' '.join(args) + ' --use_tls=true'
+        'py27/bin/python',
+        'src/python/grpcio_tests/setup.py',
+        'run_interop',
+        '--server',
+        '--args="{}"'.format(' '.join(args) + ' --use_tls=true')
     ]
 
   def global_env(self):
diff --git a/tools/run_tests/run_python.sh b/tools/run_tests/run_python.sh
index b05efd1c76..17e0186f2a 100755
--- a/tools/run_tests/run_python.sh
+++ b/tools/run_tests/run_python.sh
@@ -33,24 +33,11 @@ set -ex
 # change to grpc repo root
 cd $(dirname $0)/../..
 
-TOX_PYTHON_ENV="$1"
+PYTHON=`realpath -s "${1:-py27/bin/python}"`
 
 ROOT=`pwd`
-export LD_LIBRARY_PATH=$ROOT/libs/$CONFIG
-export DYLD_LIBRARY_PATH=$ROOT/libs/$CONFIG
-export PATH=$ROOT/bins/$CONFIG:$ROOT/bins/$CONFIG/protobuf:$PATH
-export CFLAGS="-I$ROOT/include -std=c89"
-export LDFLAGS="-L$ROOT/libs/$CONFIG"
-export GRPC_PYTHON_BUILD_WITH_CYTHON=1
-export GRPC_PYTHON_USE_PRECOMPILED_BINARIES=0
 
-if [ "$CONFIG" = "gcov" ]
-then
-  export GRPC_PYTHON_ENABLE_CYTHON_TRACING=1
-  tox -e ${TOX_PYTHON_ENV}
-else
-  $ROOT/.tox/${TOX_PYTHON_ENV}/bin/python $ROOT/src/python/grpcio_tests/setup.py test_lite
-fi
+$PYTHON $ROOT/src/python/grpcio_tests/setup.py test_lite
 
 mkdir -p $ROOT/reports
 rm -rf $ROOT/reports/python-coverage
diff --git a/tools/run_tests/run_tests.py b/tools/run_tests/run_tests.py
index f32a621ee4..fbc5729c75 100755
--- a/tools/run_tests/run_tests.py
+++ b/tools/run_tests/run_tests.py
@@ -32,11 +32,13 @@
 
 import argparse
 import ast
+import collections
 import glob
 import itertools
 import json
 import multiprocessing
 import os
+import os.path
 import platform
 import random
 import re
@@ -372,12 +374,20 @@ class PhpLanguage(object):
     return 'php'
 
 
+class PythonConfig(collections.namedtuple('PythonConfig', [
+    'python', 'venv', 'venv_relative_python', 'toolchain',])):
+
+  @property
+  def venv_python(self):
+    return os.path.abspath('{}/{}'.format(self.venv, self.venv_relative_python))
+
+
 class PythonLanguage(object):
 
   def configure(self, config, args):
     self.config = config
     self.args = args
-    self._tox_envs = self._get_tox_envs(self.args.compiler)
+    self.pythons = self._get_pythons(self.args.compiler)
 
   def test_specs(self):
     # load list of known test suites
@@ -386,33 +396,42 @@ class PythonLanguage(object):
     environment = dict(_FORCE_ENVIRON_FOR_WRAPPERS)
     if self.config.build_config != 'gcov':
       return [self.config.job_spec(
-          ['tools/run_tests/run_python.sh', tox_env],
+          ['tools/run_tests/run_python.sh', config.venv_python],
+          None,
           environ=dict(environment.items() +
                        [('GRPC_PYTHON_TESTRUNNER_FILTER', suite_name)]),
-          shortname='%s.test.%s' % (tox_env, suite_name),
+          shortname='%s.test.%s' % (config.venv, suite_name),
           timeout_seconds=5*60)
           for suite_name in tests_json
-          for tox_env in self._tox_envs]
+          for config in self.pythons]
     else:
-      return [self.config.job_spec(['tools/run_tests/run_python.sh', tox_env],
-                                   environ=environment,
-                                   shortname='%s.test.coverage' % tox_env,
-                                   timeout_seconds=15*60)
-                                   for tox_env in self._tox_envs]
+      return [self.config.job_spec(
+          ['tools/run_tests/run_python.sh', config.venv_python],
+          None,
+          environ=environment,
+          shortname='%s.test.coverage' % config.venv,
+          timeout_seconds=15*60)
+          for config in self.pythons]
 
 
   def pre_build_steps(self):
     return []
 
   def make_targets(self):
-    return ['static_c', 'grpc_python_plugin', 'shared_c']
+    return []
 
   def make_options(self):
     return []
 
   def build_steps(self):
-    return [['tools/run_tests/build_python.sh', tox_env]
-            for tox_env in self._tox_envs]
+    return [
+        [
+            'tools/run_tests/build_python.sh',
+            config.python, config.venv,
+            config.venv_relative_python, config.toolchain
+        ]
+        for config in self.pythons
+    ]
 
   def post_tests_steps(self):
     return []
@@ -423,14 +442,21 @@ class PythonLanguage(object):
   def dockerfile_dir(self):
     return 'tools/dockerfile/test/python_jessie_%s' % _docker_arch_suffix(self.args.arch)
 
-  def _get_tox_envs(self, compiler):
-    """Returns name of tox environment based on selected compiler."""
+  def _get_pythons(self, compiler):
+    if os.name == 'nt':
+      venv_relative_python = 'Scripts/python.exe'
+      toolchain = 'mingw32'
+    else:
+      venv_relative_python = 'bin/python'
+      toolchain = 'unix'
+    python27_config = PythonConfig('python2.7', 'py27', venv_relative_python, toolchain)
+    python34_config = PythonConfig('python3.4', 'py34', venv_relative_python, toolchain)
     if compiler == 'default':
-      return ('py27', 'py34')
+      return (python27_config, python34_config,)
     elif compiler == 'python2.7':
-      return ('py27',)
+      return (python27_config,)
     elif compiler == 'python3.4':
-      return ('py34',)
+      return (python34_config,)
     else:
       raise Exception('Compiler %s not supported.' % compiler)