add help output tests to traitlets.tests.utils

traitlets/tests/utils.py

@@ -0,0 +1,40 b''
+import sys
+import nose.tools as nt
+
+from subprocess import Popen, PIPE
+
+def get_output_error_code(cmd):
+    """Get stdout, stderr, and exit code from running a command"""
+    p = Popen(cmd, stdout=PIPE, stderr=PIPE)
+    out, err = p.communicate()
+    out = out.decode('utf8', 'replace')
+    err = err.decode('utf8', 'replace')
+    return out, err, p.returncode
+
+
+def check_help_output(pkg, subcommand=None):
+    """test that `python -m PKG [subcommand] -h` works"""
+    cmd = [sys.executable, '-m', pkg]
+    if subcommand:
+        cmd.extend(subcommand)
+    cmd.append('-h')
+    out, err, rc = get_output_error_code(cmd)
+    nt.assert_equal(rc, 0, err)
+    nt.assert_not_in("Traceback", err)
+    nt.assert_in("Options", out)
+    nt.assert_in("--help-all", out)
+    return out, err
+
+
+def check_help_all_output(pkg, subcommand=None):
+    """test that `python -m PKG --help-all` works"""
+    cmd = [sys.executable, '-m', pkg]
+    if subcommand:
+        cmd.extend(subcommand)
+    cmd.append('--help-all')
+    out, err, rc = get_output_error_code(cmd)
+    nt.assert_equal(rc, 0, err)
+    nt.assert_not_in("Traceback", err)
+    nt.assert_in("Options", out)
+    nt.assert_in("Class parameters", out)
+    return out, err