bpo-37064: Add option -k to Tools/scripts/pathfix.py (GH-15548)

Add flag -k to pathscript.py script: preserve shebang flags.

Lib/test/test_tools/test_pathfix.py

@@ -0,0 +1,64 @@
+import os
+import subprocess
+import sys
+import unittest
+from test import support
+from test.test_tools import import_tool, scriptsdir
+
+
+class TestPathfixFunctional(unittest.TestCase):
+    script = os.path.join(scriptsdir, 'pathfix.py')
+
+    def setUp(self):
+        self.temp_file = support.TESTFN
+        self.addCleanup(support.unlink, support.TESTFN)
+
+    def pathfix(self, shebang, pathfix_flags):
+        with open(self.temp_file, 'w', encoding='utf8') as f:
+            f.write(f'{shebang}\n' + 'print("Hello world")\n')
+
+        proc = subprocess.run(
+            [sys.executable, self.script,
+             *pathfix_flags, '-n', self.temp_file],
+            capture_output=True)
+        self.assertEqual(proc.returncode, 0, proc)
+
+        with open(self.temp_file, 'r', encoding='utf8') as f:
+            output = f.read()
+
+        lines = output.split('\n')
+        self.assertEqual(lines[1:], ['print("Hello world")', ''])
+        shebang = lines[0]
+        return shebang
+
+    def test_pathfix(self):
+        self.assertEqual(
+            self.pathfix(
+                '#! /usr/bin/env python',
+                ['-i', '/usr/bin/python3',]),
+            '#! /usr/bin/python3',
+        )
+        self.assertEqual(
+            self.pathfix(
+                '#! /usr/bin/env python -R',
+                ['-i', '/usr/bin/python3', ]),
+            '#! /usr/bin/python3',
+        )
+
+    def test_pathfix_keeping_flags(self):
+        self.assertEqual(
+            self.pathfix(
+                '#! /usr/bin/env python -R',
+                ['-i', '/usr/bin/python3', '-k',]),
+            '#! /usr/bin/python3 -R',
+        )
+        self.assertEqual(
+            self.pathfix(
+                '#! /usr/bin/env python',
+                ['-i', '/usr/bin/python3', '-k',]),
+            '#! /usr/bin/python3',
+        )
+
+
+if __name__ == '__main__':
+    unittest.main()