wip implementation of --base-url argument

Addresses httpie#838

httpie/cli/argparser.py

@@ -203,6 +203,8 @@ def _process_request_type(self):
         }
 
     def _process_url(self):
+        self.args.url = self.args.base_url + self.args.url
+
         if self.args.url.startswith('://'):
             # Paste URL & add space shortcut: `http ://pie.dev` → `http://pie.dev`
             self.args.url = self.args.url[3:]

httpie/cli/definition.py

@@ -81,6 +81,8 @@
         $ http :3000                    # => http://localhost:3000
         $ http :/foo                    # => http://localhost/foo
 
+    Prefixed with --base-url before default scheme or shorthand processing take place.
+
     """,
 )
 positional_arguments.add_argument(
@@ -713,6 +715,16 @@ def format_auth_help(auth_plugins_mapping, *, isolation_mode: bool = False):
     action='store_true',
     short_help='Build the request and print it but don’t actually send it.'
 )
+network.add_argument(
+    '--base-url',
+    default='',
+    short_help='String to prepend to the request URL.',
+    help="""
+    String to prepend to the request URL before --default-scheme and/or localhost
+    shorthand are processed. If specified multiple times, last value is used.
+
+    """
+)
 network.add_argument(
     '--proxy',
     default=[],

tests/test_cli.py

@@ -375,3 +375,8 @@ def test_default_scheme_option(self, httpbin_secure):
     def test_scheme_when_invoked_as_https(self, httpbin_secure):
         url = f'{httpbin_secure.host}:{httpbin_secure.port}'
         assert HTTP_OK in http(url, program_name='https')
+
+
+class TestBaseUrl:
+    def test_base_url(self):
+        assert False, 'Needs tests'