bpo-29636: Add --indent / --no-indent arguments to json.tool

Lib/json/tool.py

@@ -21,23 +21,42 @@ def main():
                    'to validate and pretty-print JSON objects.')
     parser = argparse.ArgumentParser(prog=prog, description=description)
     parser.add_argument('infile', nargs='?', type=argparse.FileType(),
+                        default=sys.stdin,
                         help='a JSON file to be validated or pretty-printed')
     parser.add_argument('outfile', nargs='?', type=argparse.FileType('w'),
+                        default=sys.stdout,
                         help='write the output of infile to outfile')
-    parser.add_argument('--sort-keys', action='store_true', default=False,
-                        help='sort the output of dictionaries alphabetically by key')
+    parser.add_argument('--sort-keys', action='store_true',
+                        help='sort the output of dictionaries by key')
+    group = parser.add_mutually_exclusive_group()
+    group.add_argument('--indent', default=4, type=int,
+                       help='separate items with newlines and use this number '
+                       'of spaces for indentation')
+    group.add_argument('--tab', action='store_const', dest='indent',
+                       const='\t', help='separate items with newlines and use '
+                       'tabs for indentation')
+    group.add_argument('--no-indent', action='store_const', dest='indent',
+                       const=None,
+                       help='separate items with spaces rather than newlines')
+    group.add_argument('--compact', action='store_true',
+                       help='suppress all whitespace separation (most compact)')
     options = parser.parse_args()
 
-    infile = options.infile or sys.stdin
-    outfile = options.outfile or sys.stdout
-    sort_keys = options.sort_keys
-    with infile:
+    with options.infile as infile:
         try:
             obj = json.load(infile)
         except ValueError as e:
             raise SystemExit(e)
-    with outfile:
-        json.dump(obj, outfile, sort_keys=sort_keys, indent=4)
+
+    kwargs = {
+        'indent': options.indent,
+        'sort_keys': options.sort_keys,
+    }
+    if options.compact:
+        kwargs['indent'] = None
+        kwargs['separators'] = ',', ':'
+    with options.outfile as outfile:
+        json.dump(obj, outfile, **kwargs)
         outfile.write('\n')
 
 

Lib/test/test_json/test_tool.py

@@ -105,3 +105,44 @@ def test_sort_keys_flag(self):
         self.assertEqual(out.splitlines(),
                          self.expect_without_sort_keys.encode().splitlines())
         self.assertEqual(err, b'')
+
+    def test_indent(self):
+        json_stdin = b'[1, 2]'
+        expect = textwrap.dedent('''\
+        [
+          1,
+          2
+        ]
+        ''').encode()
+        args = sys.executable, '-m', 'json.tool', '--indent', '2'
+        with Popen(args, stdin=PIPE, stdout=PIPE, stderr=PIPE) as proc:
+            json_stdout, err = proc.communicate(json_stdin)
+        self.assertEqual(expect.splitlines(), json_stdout.splitlines())
+        self.assertEqual(err, b'')
+
+    def test_no_indent(self):
+        json_stdin = b'[1,\n2]'
+        expect = b'[1, 2]'
+        args = sys.executable, '-m', 'json.tool', '--no-indent'
+        with Popen(args, stdin=PIPE, stdout=PIPE, stderr=PIPE) as proc:
+            json_stdout, err = proc.communicate(json_stdin)
+        self.assertEqual(expect.splitlines(), json_stdout.splitlines())
+        self.assertEqual(err, b'')
+
+    def test_tab(self):
+        json_stdin = b'[1, 2]'
+        expect = b'[\n\t1,\n\t2\n]\n'
+        args = sys.executable, '-m', 'json.tool', '--tab'
+        with Popen(args, stdin=PIPE, stdout=PIPE, stderr=PIPE) as proc:
+            json_stdout, err = proc.communicate(json_stdin)
+        self.assertEqual(expect.splitlines(), json_stdout.splitlines())
+        self.assertEqual(err, b'')
+
+    def test_compact(self):
+        json_stdin = b'[ 1 ,\n 2]'
+        expect = b'[1,2]'
+        args = sys.executable, '-m', 'json.tool', '--compact'
+        with Popen(args, stdin=PIPE, stdout=PIPE, stderr=PIPE) as proc:
+            json_stdout, err = proc.communicate(json_stdin)
+        self.assertEqual(expect.splitlines(), json_stdout.splitlines())
+        self.assertEqual(err, b'')

Misc/NEWS.d/next/Library/2018-02-22-11-24-33.bpo-29636.ogGRE2.rst

@@ -0,0 +1,5 @@
+Add whitespace options for formatting JSON with the ``json.tool`` CLI. The
+following mutually exclusive options are now supported: ``--indent`` for
+setting the indent level in spaces; ``--tab`` for indenting with tabs;
+``--no-indent`` for suppressing newlines; and ``--compact`` for suppressing
+all whitespace. The default behavior remains the same as ``--indent=4``.