Add Python cmdline bytecode option and set sys.executable

Closes hylang/hy#459.

hy/cmdline.py

@@ -262,6 +262,8 @@ def cmdline_handler(scriptname, argv):
                         help="module to run, passed in as a string")
     parser.add_argument("-E", action='store_true',
                         help="ignore PYTHON* environment variables")
+    parser.add_argument("-B", action='store_true',
+                        help="don't write .py[co] files on import; also PYTHONDONTWRITEBYTECODE=x")
     parser.add_argument("-i", dest="icommand",
                         help="program passed in as a string, then stay in REPL")
     parser.add_argument("--spy", action="store_true",
@@ -278,13 +280,17 @@ def cmdline_handler(scriptname, argv):
     parser.add_argument('args', nargs=argparse.REMAINDER,
                         help=argparse.SUPPRESS)
 
-    # stash the hy executable in case we need it later
-    # mimics Python sys.executable
+    # Get the path of the Hy cmdline executable and swap it with
+    # `sys.executable` (saving the original, just in case).
+    # XXX: The `__main__` module will also have `__file__` set to the
+    # entry-point script.  Currently, I don't see an immediate problem, but
+    # that's not how the Python cmdline works.
     hy.executable = argv[0]
+    hy.sys_executable = sys.executable
+    sys.executable = hy.executable
 
-    # need to split the args if using "-m"
-    # all args after the MOD are sent to the module
-    # in sys.argv
+    # Need to split the args.  If using "-m" all args after the MOD are sent to
+    # the module in sys.argv.
     module_args = []
     if "-m" in argv:
         mloc = argv.index("-m")
@@ -298,13 +304,13 @@ def cmdline_handler(scriptname, argv):
         global SIMPLE_TRACEBACKS
         SIMPLE_TRACEBACKS = False
 
-    # reset sys.argv like Python
-    # sys.argv = [sys.argv[0]] + options.args + module_args
-
     if options.E:
         # User did "hy -E ..."
         _remove_python_envs()
 
+    if options.B:
+        sys.dont_write_bytecode = True
+
     if options.command:
         # User did "hy -c ..."
         return run_command(options.command)

tests/importer/test_importer.py

@@ -84,7 +84,7 @@ def test_import_error_reporting():
     assert _import_error_test() is not None
 
 
-@pytest.mark.skipif(os.environ.get('PYTHONDONTWRITEBYTECODE'),
+@pytest.mark.skipif(sys.dont_write_bytecode,
                     reason="Bytecode generation is suppressed")
 def test_import_autocompiles():
     "Test that (import) byte-compiles the module."

tests/test_bin.py

@@ -6,6 +6,7 @@
 
 import os
 import re
+import sys
 import shlex
 import subprocess
 
@@ -285,15 +286,20 @@ def test_bin_hy_no_main():
     assert "This Should Still Work" in output
 
 
-@pytest.mark.parametrize('scenario', [
-    "normal", "prevent_by_force", "prevent_by_env"])
-@pytest.mark.parametrize('cmd_fmt', [
-    'hy -m {modname}', "hy -c '(import {modname})'"])
+@pytest.mark.parametrize('scenario', ["normal", "prevent_by_force",
+                                      "prevent_by_env", "prevent_by_option"])
+@pytest.mark.parametrize('cmd_fmt', [['hy', '{fpath}'],
+                                     ['hy', '-m', '{modname}'],
+                                     ['hy', '-c', "'(import {modname})'"]])
 def test_bin_hy_byte_compile(scenario, cmd_fmt):
 
     modname = "tests.resources.bin.bytecompile"
     fpath = modname.replace(".", "/") + ".hy"
-    cmd = cmd_fmt.format(**locals())
+
+    if scenario == 'prevent_by_option':
+        cmd_fmt.insert(1, '-B')
+
+    cmd = ' '.join(cmd_fmt).format(**locals())
 
     rm(cache_from_source(fpath))
 
@@ -304,14 +310,14 @@ def test_bin_hy_byte_compile(scenario, cmd_fmt):
 
     # Whether or not we can byte-compile the module, we should be able
     # to run it.
-    output, _ = run_cmd(cmd, dontwritebytecode=scenario == "prevent_by_env")
+    output, _ = run_cmd(cmd, dontwritebytecode=(scenario == "prevent_by_env"))
     assert "Hello from macro" in output
     assert "The macro returned: boink" in output
 
     if scenario == "normal":
         # That should've byte-compiled the module.
         assert os.path.exists(cache_from_source(fpath))
-    elif scenario == "prevent_by_env":
+    elif scenario == "prevent_by_env" or scenario == "prevent_by_option":
         # No byte-compiled version should've been created.
         assert not os.path.exists(cache_from_source(fpath))
 
@@ -353,3 +359,8 @@ def test_bin_hy_module_main_exitvalue():
 def test_bin_hy_module_no_main():
     output, _ = run_cmd("hy -m tests.resources.bin.nomain")
     assert "This Should Still Work" in output
+
+
+def test_bin_hy_sys_executable():
+    output, _ = run_cmd("hy -c '(do (import sys) (print sys.executable))'")
+    assert output.strip().endswith('/hy')