Separate __main__ and main() to allow for testing

Also reference example in:
https://github.com/ionelmc/cookiecutter-pylibrary

3 files changed, 173 insertions, 136 deletions

diff --git a/sqlparse/__init__.py b/sqlparse/__init__.py
index 03f74d1..5c10f14 100644
--- a/sqlparse/__init__.py
+++ b/sqlparse/__init__.py
@@ -9,6 +9,7 @@
 
 # Setup namespace
 from sqlparse import sql
+from sqlparse import cli
 from sqlparse import engine
 from sqlparse import tokens
 from sqlparse import filters
@@ -17,7 +18,7 @@ from sqlparse import formatter
 from sqlparse.compat import text_type
 
 __version__ = '0.2.0.dev0'
-__all__ = ['engine', 'filters', 'formatter', 'sql', 'tokens']
+__all__ = ['engine', 'filters', 'formatter', 'sql', 'tokens', 'cli']
 
 
 def parse(sql, encoding=None):
diff --git a/sqlparse/__main__.py b/sqlparse/__main__.py
index e6c6ed7..0020038 100644
--- a/sqlparse/__main__.py
+++ b/sqlparse/__main__.py
@@ -6,144 +6,17 @@
 # This module is part of python-sqlparse and is released under
 # the BSD License: http://www.opensource.org/licenses/bsd-license.php
 
-import argparse
-import sys
-
-import sqlparse
-from sqlparse.compat import PY2
-from sqlparse.exceptions import SQLParseError
-
-_CASE_CHOICES = ['upper', 'lower', 'capitalize']
-
-# TODO: Add CLI Tests
-# TODO: Simplify formatter by using argparse `type` arguments
-parser = argparse.ArgumentParser(
-    prog='sqlformat',
-    description='Format FILE according to OPTIONS. Use "-" as FILE '
-                'to read from stdin.',
-    usage='%(prog)s  [OPTIONS] FILE, ...',
-)
-
-parser.add_argument('filename')
-
-parser.add_argument(
-    '-o', '--outfile',
-    dest='outfile',
-    metavar='FILE',
-    help='write output to FILE (defaults to stdout)')
-
-parser.add_argument(
-    '--version',
-    action='version',
-    version=sqlparse.__version__)
-
-group = parser.add_argument_group('Formatting Options')
-
-group.add_argument(
-    '-k', '--keywords',
-    metavar='CHOICE',
-    dest='keyword_case',
-    choices=_CASE_CHOICES,
-    help='change case of keywords, CHOICE is one of {0}'.format(
-        ', '.join('"{0}"'.format(x) for x in _CASE_CHOICES)))
-
-group.add_argument(
-    '-i', '--identifiers',
-    metavar='CHOICE',
-    dest='identifier_case',
-    choices=_CASE_CHOICES,
-    help='change case of identifiers, CHOICE is one of {0}'.format(
-        ', '.join('"{0}"'.format(x) for x in _CASE_CHOICES)))
-
-group.add_argument(
-    '-l', '--language',
-    metavar='LANG',
-    dest='output_format',
-    choices=['python', 'php'],
-    help='output a snippet in programming language LANG, '
-         'choices are "python", "php"')
-
-group.add_argument(
-    '--strip-comments',
-    dest='strip_comments',
-    action='store_true',
-    default=False,
-    help='remove comments')
+"""Entrypoint module for `python -m sqlparse`.
 
-group.add_argument(
-    '-r', '--reindent',
-    dest='reindent',
-    action='store_true',
-    default=False,
-    help='reindent statements')
+Why does this file exist, and why __main__? For more info, read:
+- https://www.python.org/dev/peps/pep-0338/
+- https://docs.python.org/2/using/cmdline.html#cmdoption-m
+- https://docs.python.org/3/using/cmdline.html#cmdoption-m
+"""
 
-group.add_argument(
-    '--indent_width',
-    dest='indent_width',
-    default=2,
-    type=int,
-    help='indentation width (defaults to 2 spaces)')
-
-group.add_argument(
-    '-a', '--reindent_aligned',
-    action='store_true',
-    default=False,
-    help='reindent statements to aligned format')
-
-group.add_argument(
-    '-s', '--use_space_around_operators',
-    action='store_true',
-    default=False,
-    help='place spaces around mathematical operators')
-
-group.add_argument(
-    '--wrap_after',
-    dest='wrap_after',
-    default=0,
-    type=int,
-    help='Column after which lists should be wrapped')
-
-
-def _error(msg):
-    """Print msg and optionally exit with return code exit_."""
-    sys.stderr.write('[ERROR] %s\n' % msg)
-
-
-def main(args=None):
-    args = parser.parse_args(args)
-
-    if args.filename == '-':  # read from stdin
-        data = sys.stdin.read()
-    else:
-        try:
-            data = ''.join(open(args.filename).readlines())
-        except IOError as e:
-            _error('Failed to read %s: %s' % (args.filename, e))
-            return 1
-
-    if args.outfile:
-        try:
-            stream = open(args.outfile, 'w')
-        except IOError as e:
-            _error('Failed to open %s: %s' % (args.outfile, e))
-            return 1
-    else:
-        stream = sys.stdout
-
-    formatter_opts = vars(args)
-    try:
-        formatter_opts = sqlparse.formatter.validate_options(formatter_opts)
-    except SQLParseError as e:
-        _error('Invalid options: %s' % e)
-        return 1
-
-    s = sqlparse.format(data, **formatter_opts)
-    if PY2:
-        s = s.encode('utf-8', 'replace')
-    stream.write(s)
-    stream.flush()
-    return 0
+import sys
 
+from sqlparse.cli import main
 
 if __name__ == '__main__':
     sys.exit(main())
diff --git a/sqlparse/cli.py b/sqlparse/cli.py
new file mode 100644
index 0000000..1009413
--- /dev/null
+++ b/sqlparse/cli.py
@@ -0,0 +1,163 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+#
+# Copyright (C) 2016 Andi Albrecht, albrecht.andi@gmail.com
+#
+# This module is part of python-sqlparse and is released under
+# the BSD License: http://www.opensource.org/licenses/bsd-license.php
+
+"""Module that contains the command line app.
+
+Why does this file exist, and why not put this in __main__?
+  You might be tempted to import things from __main__ later, but that will
+  cause problems: the code will get executed twice:
+  - When you run `python -m sqlparse` python will execute
+    ``__main__.py`` as a script. That means there won't be any
+    ``sqlparse.__main__`` in ``sys.modules``.
+  - When you import __main__ it will get executed again (as a module) because
+    there's no ``sqlparse.__main__`` in ``sys.modules``.
+  Also see (1) from http://click.pocoo.org/5/setuptools/#setuptools-integration
+"""
+
+import argparse
+import sys
+
+import sqlparse
+from sqlparse.compat import PY2
+from sqlparse.exceptions import SQLParseError
+
+
+# TODO: Add CLI Tests
+# TODO: Simplify formatter by using argparse `type` arguments
+def create_parser():
+    _CASE_CHOICES = ['upper', 'lower', 'capitalize']
+
+    parser = argparse.ArgumentParser(
+        prog='sqlformat',
+        description='Format FILE according to OPTIONS. Use "-" as FILE '
+                    'to read from stdin.',
+        usage='%(prog)s  [OPTIONS] FILE, ...',
+    )
+
+    parser.add_argument('filename')
+
+    parser.add_argument(
+        '-o', '--outfile',
+        dest='outfile',
+        metavar='FILE',
+        help='write output to FILE (defaults to stdout)')
+
+    parser.add_argument(
+        '--version',
+        action='version',
+        version=sqlparse.__version__)
+
+    group = parser.add_argument_group('Formatting Options')
+
+    group.add_argument(
+        '-k', '--keywords',
+        metavar='CHOICE',
+        dest='keyword_case',
+        choices=_CASE_CHOICES,
+        help='change case of keywords, CHOICE is one of {0}'.format(
+            ', '.join('"{0}"'.format(x) for x in _CASE_CHOICES)))
+
+    group.add_argument(
+        '-i', '--identifiers',
+        metavar='CHOICE',
+        dest='identifier_case',
+        choices=_CASE_CHOICES,
+        help='change case of identifiers, CHOICE is one of {0}'.format(
+            ', '.join('"{0}"'.format(x) for x in _CASE_CHOICES)))
+
+    group.add_argument(
+        '-l', '--language',
+        metavar='LANG',
+        dest='output_format',
+        choices=['python', 'php'],
+        help='output a snippet in programming language LANG, '
+             'choices are "python", "php"')
+
+    group.add_argument(
+        '--strip-comments',
+        dest='strip_comments',
+        action='store_true',
+        default=False,
+        help='remove comments')
+
+    group.add_argument(
+        '-r', '--reindent',
+        dest='reindent',
+        action='store_true',
+        default=False,
+        help='reindent statements')
+
+    group.add_argument(
+        '--indent_width',
+        dest='indent_width',
+        default=2,
+        type=int,
+        help='indentation width (defaults to 2 spaces)')
+
+    group.add_argument(
+        '-a', '--reindent_aligned',
+        action='store_true',
+        default=False,
+        help='reindent statements to aligned format')
+
+    group.add_argument(
+        '-s', '--use_space_around_operators',
+        action='store_true',
+        default=False,
+        help='place spaces around mathematical operators')
+
+    group.add_argument(
+        '--wrap_after',
+        dest='wrap_after',
+        default=0,
+        type=int,
+        help='Column after which lists should be wrapped')
+
+    return parser
+
+
+def _error(msg):
+    """Print msg and optionally exit with return code exit_."""
+    sys.stderr.write('[ERROR] %s\n' % msg)
+
+
+def main(args=None):
+    parser = create_parser()
+    args = parser.parse_args(args)
+
+    if args.filename == '-':  # read from stdin
+        data = sys.stdin.read()
+    else:
+        try:
+            data = ''.join(open(args.filename).readlines())
+        except IOError as e:
+            _error('Failed to read %s: %s' % (args.filename, e))
+            return 1
+
+    if args.outfile:
+        try:
+            stream = open(args.outfile, 'w')
+        except IOError as e:
+            _error('Failed to open %s: %s' % (args.outfile, e))
+            return 1
+    else:
+        stream = sys.stdout
+
+    formatter_opts = vars(args)
+    try:
+        formatter_opts = sqlparse.formatter.validate_options(formatter_opts)
+    except SQLParseError as e:
+        _error('Invalid options: %s' % e)
+        return 1
+
+    s = sqlparse.format(data, **formatter_opts)
+    if PY2:
+        s = s.encode('utf-8', 'replace')
+    stream.write(s)
+    stream.flush()
+    return 0