Merge pull request #218 from hroncok/issue211

Command not found will no longer traceback

Author: kevin-bates

jupyter_core/command.py

@@ -282,7 +282,10 @@ def main():
         parser.print_usage(file=sys.stderr)
         sys.exit("subcommand is required")
 
-    command = _jupyter_abspath(subcommand)
+    try:
+        command = _jupyter_abspath(subcommand)
+    except Exception as e:
+        sys.exit(e)
 
     try:
         _execvp(command, sys.argv[1:])

jupyter_core/tests/test_command.py

@@ -4,7 +4,7 @@
 import os
 import sys
 import sysconfig
-from subprocess import check_output, CalledProcessError
+from subprocess import check_output, PIPE, CalledProcessError
 from unittest.mock import patch
 
 import pytest
@@ -21,7 +21,7 @@ def get_jupyter_output(cmd):
     """Get output of a jupyter command"""
     if not isinstance(cmd, list):
         cmd = [cmd]
-    return check_output([sys.executable, '-m', 'jupyter_core'] + cmd).decode('utf8').strip()
+    return check_output([sys.executable, '-m', 'jupyter_core'] + cmd, stderr=PIPE).decode('utf8').strip()
 
 
 def write_executable(path, source):
@@ -109,8 +109,10 @@ def test_help():
 
 
 def test_subcommand_not_found():
-    with pytest.raises(CalledProcessError):
+    with pytest.raises(CalledProcessError) as excinfo:
         get_jupyter_output('nonexistant-subcommand')
+    stderr = excinfo.value.stderr.decode('utf8')
+    assert stderr == 'Jupyter command `jupyter-nonexistant-subcommand` not found.' + os.linesep
 
 @patch.object(sys, 'argv', [__file__] + sys.argv[1:])
 def test_subcommand_list(tmpdir):