Add testing script for local lint and python test. (#3797)

* Add presubmit testing script for local testing.

* Update the test script to be more modularized.

1. Check the script file location and cd into repo root dir.
2. Allow caller to call differnt tests.

official/utils/testing/scripts/presubmit.sh

+#!/bin/bash
+
+# Presubmit script that run tests and lint under local environment.
+# Make sure that tensorflow and pylint is installed.
+# usage: models >: ./official/utils/testing/scripts/presubmit.sh
+# usage: models >: ./official/utils/testing/scripts/presubmit.sh lint py2_test py3_test
+set +x
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+cd "$SCRIPT_DIR/../../../.."
+MODEL_ROOT="$(pwd)"
+
+export PYTHONPATH="$PYTHONPATH:${MODEL_ROOT}"
+
+cd official
+
+lint() {
+  local exit_code=0
+
+  RC_FILE="utils/testing/pylint.rcfile"
+
+  echo "===========Running lint test============"
+  for file in `find . -name '*.py' ! -name '*test.py' -print`
+  do
+    echo "Linting ${file}"
+    pylint --rcfile="${RC_FILE}" "${file}" || exit_code=$?
+  done
+
+  # More lenient for test files.
+  for file in `find . -name '*test.py' -print`
+  do
+    echo "Linting ${file}"
+    pylint --rcfile="${RC_FILE}" --disable=missing-docstring,protected-access "${file}" || exit_code=$?
+  done
+
+  return "${exit_code}"
+}
+
+py_test() {
+  local PY_BINARY="$1"
+  local exit_code=0
+
+  echo "===========Running Python test============"
+
+  for test_file in `find . -name '*test.py' -print`
+  do
+    echo "Testing ${test_file}"
+    ${PY_BINARY} "${test_file}" || exit_code=$?
+  done
+
+  return "${exit_code}"
+}
+
+py2_test() {
+  local PY_BINARY=$(which python2)
+  return $(py_test "${PY_BINARY}")
+}
+
+py3_test() {
+  local PY_BINARY=$(which python3)
+  return $(py_test "${PY_BINARY}")
+}
+
+test_result=0
+
+if [ "$#" -eq 0 ]; then
+  TESTS="lint py2_test py3_test"
+else
+  TESTS="$@"
+fi
+
+for t in "${TESTS}"; do
+  ${t} || test_result=$?
+done
+
+exit "${test_result}"