tests-httpd: basic infra to run curl against an apache httpd plus nghttpx for h3

- adding '--with-test-httpd=<path>' to configure non-standard apache2
  install
- python env and base classes for running httpd
- basic tests for connectivity with h1/h2/h3
- adding test cases for truncated responses in http versions.
- adding goaway test for HTTP/3.
- adding "stuttering" tests with parallel downloads in chunks with
  varying delays between chunks.

- adding a curltest module to the httpd server, adding GOAWAY test.
    - mod_curltest now installs 2 handlers
      - 'echo': writing as response body what came as request body
      - 'tweak': with query parameters to tweak response behaviour
- marked known fails as skip for now

Closes #10175

tests/tests-httpd/test_01_basic.py

@@ -0,0 +1,89 @@
+#!/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 pytest
+
+from testenv import Env
+from testenv import CurlClient
+
+
+log = logging.getLogger(__name__)
+
+
+@pytest.mark.skipif(condition=Env.setup_incomplete(),
+                    reason=f"missing: {Env.incomplete_reason()}")
+class TestBasic:
+
+    # simple http: GET
+    def test_01_01_http_get(self, env: Env, httpd):
+        curl = CurlClient(env=env)
+        url = f'http://{env.domain1}:{env.http_port}/data.json'
+        r = curl.http_get(url=url)
+        assert r.exit_code == 0
+        assert r.response['status'] == 200
+        assert r.json['server'] == env.domain1
+
+    # simple https: GET, any http version
+    def test_01_02_https_get(self, env: Env, httpd):
+        curl = CurlClient(env=env)
+        url = f'https://{env.domain1}:{env.https_port}/data.json'
+        r = curl.http_get(url=url)
+        assert r.exit_code == 0
+        assert r.response['status'] == 200
+        assert r.json['server'] == env.domain1
+
+    # simple https: GET, h2 wanted and got
+    def test_01_02_h2_get(self, env: Env, httpd):
+        curl = CurlClient(env=env)
+        url = f'https://{env.domain1}:{env.https_port}/data.json'
+        r = curl.http_get(url=url, extra_args=['--http2'])
+        assert r.exit_code == 0
+        assert r.response['status'] == 200
+        assert r.response['protocol'] == 'HTTP/2'
+        assert r.json['server'] == env.domain1
+
+    # simple https: GET, h2 unsupported, fallback to h1
+    def test_01_02_h2_unsupported(self, env: Env, httpd):
+        curl = CurlClient(env=env)
+        url = f'https://{env.domain2}:{env.https_port}/data.json'
+        r = curl.http_get(url=url, extra_args=['--http2'])
+        assert r.exit_code == 0
+        assert r.response['status'] == 200
+        assert r.response['protocol'] == 'HTTP/1.1'
+        assert r.json['server'] == env.domain2
+
+    # simple h3: GET, want h3 and get it
+    @pytest.mark.skipif(condition=not Env.have_h3_curl(), reason="no h3 curl")
+    @pytest.mark.skipif(condition=not Env.have_h3_server(), reason="no h3 server")
+    def test_01_03_h3_get(self, env: Env, httpd, nghttpx):
+        curl = CurlClient(env=env)
+        url = f'https://{env.domain1}:{env.h3_port}/data.json'
+        r = curl.http_get(url=url, extra_args=['--http3'])
+        assert r.exit_code == 0, f'{r}'
+        assert r.response['status'] == 200
+        assert r.response['protocol'] == 'HTTP/3'
+        assert r.json['server'] == env.domain1