Add test case that fails on main

Author: hugovk

Lib/test/test_json/json_lines.jsonl

@@ -0,0 +1,2 @@
+{"ingredients":["frog", "water", "chocolate", "glucose"]}
+{"ingredients":["chocolate","steel bolts"]}

Lib/test/test_json/test_tool.py

@@ -1,4 +1,5 @@
 import errno
+import pathlib
 import os
 import sys
 import textwrap
@@ -156,6 +157,14 @@ def test_jsonlines(self):
         self.assertEqual(process.stdout, self.jsonlines_expect)
         self.assertEqual(process.stderr, '')
 
+    @force_not_colorized
+    def test_jsonlines_from_file(self):
+        jsonl = pathlib.Path(__file__).parent / 'json_lines.jsonl'
+        args = sys.executable, '-m', self.module, '--json-lines', jsonl
+        process = subprocess.run(args, capture_output=True, text=True, check=True)
+        self.assertEqual(process.stdout, self.jsonlines_expect)
+        self.assertEqual(process.stderr, '')
+
     def test_help_flag(self):
         rc, out, err = assert_python_ok('-m', self.module, '-h',
                                         PYTHON_COLORS='0')