pytest: add a test case for PUSH related things.

- checking that "103 Early Hints" are visible in curl's header dump file

Closes #10452

tests/tests-httpd/test_09_push.py

@@ -0,0 +1,72 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+#***************************************************************************
+#                                  _   _ ____  _
+#  Project                     ___| | | |  _ \| |
+#                             / __| | | | |_) | |
+#                            | (__| |_| |  _ <| |___
+#                             \___|\___/|_| \_\_____|
+#
+# Copyright (C) 2008 - 2022, Daniel Stenberg, <daniel@haxx.se>, et al.
+#
+# This software is licensed as described in the file COPYING, which
+# you should have received as part of this distribution. The terms
+# are also available at https://curl.se/docs/copyright.html.
+#
+# You may opt to use, copy, modify, merge, publish, distribute and/or sell
+# copies of the Software, and permit persons to whom the Software is
+# furnished to do so, under the terms of the COPYING file.
+#
+# This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+# KIND, either express or implied.
+#
+# SPDX-License-Identifier: curl
+#
+###########################################################################
+#
+import logging
+import os
+import pytest
+
+from testenv import Env, CurlClient
+
+
+log = logging.getLogger(__name__)
+
+
+@pytest.mark.skipif(condition=Env.setup_incomplete(),
+                    reason=f"missing: {Env.incomplete_reason()}")
+class TestPush:
+
+    @pytest.fixture(autouse=True, scope='class')
+    def _class_scope(self, env, httpd):
+        push_dir = os.path.join(httpd.docs_dir, 'push')
+        if not os.path.exists(push_dir):
+            os.makedirs(push_dir)
+        env.make_data_file(indir=push_dir, fname="data1", fsize=100*1024)
+        env.make_data_file(indir=push_dir, fname="data2", fsize=100*1024)
+        env.make_data_file(indir=push_dir, fname="data3", fsize=100*1024)
+        httpd.set_extra_config(env.domain1, [
+            f'H2EarlyHints on',
+            f'<Location /push/data1>',
+            f'  H2PushResource /push/data2',
+            f'</Location>',
+            f'<Location /push/data2>',
+            f'  H2PushResource /push/data1',
+            f'  H2PushResource /push/data3',
+            f'</Location>',
+        ])
+        # activate the new config
+        httpd.reload()
+
+    # download a file that triggers a "103 Early Hints" response
+    def test_09_01_early_hints(self, env: Env, httpd, repeat):
+        curl = CurlClient(env=env)
+        url = f'https://{env.domain1}:{env.https_port}/push/data1'
+        r = curl.http_download(urls=[url], alpn_proto='h2', with_stats=False,
+                               with_headers=True)
+        assert r.exit_code == 0, f'{r}'
+        assert len(r.responses) == 2, f'{r.responses}'
+        assert r.responses[0]['status'] == 103, f'{r.responses}'
+        assert 'link' in r.responses[0]['header'], f'{r.responses[0]}'
+        assert r.responses[0]['header']['link'] == '</push/data2>; rel=preload', f'{r.responses[0]}'