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.

1 files changed, 58 insertions, 13 deletions

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