Add tests for py(2|3)-cmd

Test: m par_test{,3} py{2,3}-cmd; ./runtest.sh
Change-Id: I4aadd9fc85be4381bd9a0843064ceaa87150b5ee
diff --git a/python/tests/py-cmd_test.py b/python/tests/py-cmd_test.py
new file mode 100644
index 0000000..acda2d7
--- /dev/null
+++ b/python/tests/py-cmd_test.py
@@ -0,0 +1,78 @@
+# Copyright 2020 Google Inc. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import os
+import site
+import sys
+
+# This file checks the visible python state against expected values when run
+# using a prebuilt python.
+
+failed = False
+def assert_equal(what, a, b):
+    global failed
+    if a != b:
+        print("Expected %s('%s') == '%s'" % (what, a, b))
+        failed = True
+
+assert_equal("__name__", __name__, "__main__")
+assert_equal("os.path.basename(__file__)", os.path.basename(__file__), "py-cmd_test.py")
+
+if os.getenv('ARGTEST', False):
+    assert_equal("len(sys.argv)", len(sys.argv), 3)
+    assert_equal("sys.argv[1]", sys.argv[1], "arg1")
+    assert_equal("sys.argv[2]", sys.argv[2], "arg2")
+elif os.getenv('ARGTEST2', False):
+    assert_equal("len(sys.argv)", len(sys.argv), 3)
+    assert_equal("sys.argv[1]", sys.argv[1], "--arg1")
+    assert_equal("sys.argv[2]", sys.argv[2], "arg2")
+else:
+    assert_equal("len(sys.argv)", len(sys.argv), 1)
+
+if os.getenv('ARGTEST_ONLY', False):
+    if failed:
+        sys.exit(1)
+    sys.exit(0)
+
+assert_equal("__package__", __package__, None)
+assert_equal("sys.argv[0]", sys.argv[0], 'py-cmd_test.py')
+if sys.version_info[0] == 2:
+    assert_equal("basename(sys.executable)", os.path.basename(sys.executable), 'py2-cmd')
+else:
+    assert_equal("basename(sys.executable)", os.path.basename(sys.executable), 'py3-cmd')
+assert_equal("sys.exec_prefix", sys.exec_prefix, sys.executable)
+assert_equal("sys.prefix", sys.prefix, sys.executable)
+assert_equal("site.ENABLE_USER_SITE", site.ENABLE_USER_SITE, None)
+
+if sys.version_info[0] == 2:
+    assert_equal("len(sys.path)", len(sys.path), 4)
+    assert_equal("sys.path[0]", sys.path[0], os.path.dirname(__file__))
+    assert_equal("sys.path[1]", sys.path[1], "/extra")
+    assert_equal("sys.path[2]", sys.path[2], os.path.join(sys.executable, "internal"))
+    assert_equal("sys.path[3]", sys.path[3], os.path.join(sys.executable, "internal", "stdlib"))
+else:
+    assert_equal("len(sys.path)", len(sys.path), 8)
+    assert_equal("sys.path[0]", sys.path[0], os.path.abspath(os.path.dirname(__file__)))
+    assert_equal("sys.path[1]", sys.path[1], "/extra")
+    assert_equal("sys.path[2]", sys.path[2], os.path.join(sys.executable, 'lib', 'python' + str(sys.version_info[0]) + str(sys.version_info[1]) + '.zip'))
+    assert_equal("sys.path[3]", sys.path[3], os.path.join(sys.executable, 'lib', 'python' + str(sys.version_info[0]) + '.' + str(sys.version_info[1]), '..'))
+    assert_equal("sys.path[4]", sys.path[4], os.path.join(sys.executable, 'lib', 'python' + str(sys.version_info[0]) + '.' + str(sys.version_info[1])))
+    assert_equal("sys.path[5]", sys.path[5], os.path.join(sys.executable, 'lib', 'python' + str(sys.version_info[0]) + '.' + str(sys.version_info[1]), 'lib-dynload'))
+    assert_equal("sys.path[6]", sys.path[6], os.path.join(sys.executable, "internal"))
+    assert_equal("sys.path[7]", sys.path[7], os.path.join(sys.executable, "internal", "stdlib"))
+
+if failed:
+    sys.exit(1)
+
+import testpkg.pycmd_test