feat: add flag to get version number

pycgtool/__main__.py

@@ -4,6 +4,7 @@ import argparse
 import cProfile
 import logging
 import pathlib
+import pkg_resources
 import sys
 import textwrap
 import time
@@ -143,10 +144,14 @@ class BooleanAction(argparse.Action):
 def parse_arguments(arg_list):
     # yapf: disable
     parser = argparse.ArgumentParser(
+        prog='pycgtool',
         formatter_class=argparse.ArgumentDefaultsHelpFormatter,
         description="Generate coarse-grained molecular dynamics models from atomistic trajectories."
     )
 
+    parser.add_argument('-v', '--version', action='version',
+                        version=pkg_resources.get_distribution('pycgtool').version)
+
     # Input files
     input_files = parser.add_argument_group("input files")
 

tests/test_pycgtool.py

@@ -42,11 +42,13 @@ class PycgtoolTest(unittest.TestCase):
     base_dir = pathlib.Path(__file__).absolute().parent
     data_dir = base_dir.joinpath('data')
 
-    def test_run_help(self):
-        self.assertEqual(
-            0,
-            subprocess.check_call(["python", "-m", "pycgtool", "-h"],
-                                  stdout=subprocess.PIPE))
+    def test_pycgtool_help(self):
+        subprocess.check_call(["python", "-m", "pycgtool", "-h"])
+        subprocess.check_call(["python", "-m", "pycgtool", "--help"])
+
+    def test_pycgtool_version(self):
+        subprocess.check_call(['python', '-m', 'pycgtool', '-v'])
+        subprocess.check_call(['python', '-m', 'pycgtool', '--version'])
 
     def test_parse_arguments(self):
         args = main.parse_arguments([