Testing: Refactor support code out of zope.testing entrypoint

`tests.py` is the entrypoint file that will be used by `zope.testing` to
discover the test cases on behalf of what's returned from `test_suite`.

It is better to not overload it with other support code that may also be
needed in other contexts.

src/crate/client/test_support.py

@@ -0,0 +1,273 @@
+# -*- coding: utf-8; -*-
+#
+# Licensed to CRATE Technology GmbH ("Crate") under one or more contributor
+# license agreements.  See the NOTICE file distributed with this work for
+# additional information regarding copyright ownership.  Crate licenses
+# this file to you under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.  You may
+# obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+# License for the specific language governing permissions and limitations
+# under the License.
+#
+# However, if you have executed another commercial license agreement
+# with Crate these terms will supersede the license and you may use the
+# software solely pursuant to the terms of the relevant commercial agreement.
+
+from __future__ import absolute_import
+
+import json
+import os
+import socket
+import unittest
+from pprint import pprint
+from http.server import HTTPServer, BaseHTTPRequestHandler
+import ssl
+import time
+import threading
+import logging
+
+import stopit
+
+from crate.testing.layer import CrateLayer
+from crate.testing.settings import \
+    crate_host, crate_path, crate_port, \
+    crate_transport_port, docs_path, localhost
+from crate.client import connect
+
+
+makeSuite = unittest.TestLoader().loadTestsFromTestCase
+
+log = logging.getLogger('crate.testing.layer')
+ch = logging.StreamHandler()
+ch.setLevel(logging.ERROR)
+log.addHandler(ch)
+
+
+def cprint(s):
+    if isinstance(s, bytes):
+        s = s.decode('utf-8')
+    print(s)
+
+
+settings = {
+    'udc.enabled': 'false',
+    'lang.js.enabled': 'true',
+    'auth.host_based.enabled': 'true',
+    'auth.host_based.config.0.user': 'crate',
+    'auth.host_based.config.0.method': 'trust',
+    'auth.host_based.config.98.user': 'trusted_me',
+    'auth.host_based.config.98.method': 'trust',
+    'auth.host_based.config.99.user': 'me',
+    'auth.host_based.config.99.method': 'password',
+}
+crate_layer = None
+
+
+def ensure_cratedb_layer():
+    """
+    In order to skip individual tests by manually disabling them within
+    `def test_suite()`, it is crucial make the test layer not run on each
+    and every occasion. So, things like this will be possible::
+
+        ./bin/test -vvvv --ignore_dir=testing
+
+    TODO: Through a subsequent patch, the possibility to individually
+          unselect specific tests might be added to `def test_suite()`
+          on behalf of environment variables.
+          A blueprint for this kind of logic can be found at
+          https://github.com/crate/crate/commit/414cd833.
+    """
+    global crate_layer
+
+    if crate_layer is None:
+        crate_layer = CrateLayer('crate',
+                                 crate_home=crate_path(),
+                                 port=crate_port,
+                                 host=localhost,
+                                 transport_port=crate_transport_port,
+                                 settings=settings)
+    return crate_layer
+
+
+def setUpCrateLayerBaseline(test):
+    if hasattr(test, "globs"):
+        test.globs['crate_host'] = crate_host
+        test.globs['pprint'] = pprint
+        test.globs['print'] = cprint
+
+    with connect(crate_host) as conn:
+        cursor = conn.cursor()
+
+        with open(docs_path('testing/testdata/mappings/locations.sql')) as s:
+            stmt = s.read()
+            cursor.execute(stmt)
+            stmt = ("select count(*) from information_schema.tables "
+                    "where table_name = 'locations'")
+            cursor.execute(stmt)
+            assert cursor.fetchall()[0][0] == 1
+
+        data_path = docs_path('testing/testdata/data/test_a.json')
+        # load testing data into crate
+        cursor.execute("copy locations from ?", (data_path,))
+        # refresh location table so imported data is visible immediately
+        cursor.execute("refresh table locations")
+        # create blob table
+        cursor.execute("create blob table myfiles clustered into 1 shards " +
+                       "with (number_of_replicas=0)")
+
+        # create users
+        cursor.execute("CREATE USER me WITH (password = 'my_secret_pw')")
+        cursor.execute("CREATE USER trusted_me")
+
+        cursor.close()
+
+
+def tearDownDropEntitiesBaseline(test):
+    """
+    Drop all tables, views, and users created by `setUpWithCrateLayer*`.
+    """
+    ddl_statements = [
+        "DROP TABLE foobar",
+        "DROP TABLE locations",
+        "DROP BLOB TABLE myfiles",
+        "DROP USER me",
+        "DROP USER trusted_me",
+    ]
+    _execute_statements(ddl_statements)
+
+
+class HttpsTestServerLayer:
+    PORT = 65534
+    HOST = "localhost"
+    CERT_FILE = os.path.abspath(os.path.join(os.path.dirname(__file__),
+                                "pki/server_valid.pem"))
+    CACERT_FILE = os.path.abspath(os.path.join(os.path.dirname(__file__),
+                                  "pki/cacert_valid.pem"))
+
+    __name__ = "httpsserver"
+    __bases__ = tuple()
+
+    class HttpsServer(HTTPServer):
+        def get_request(self):
+
+            # Prepare SSL context.
+            context = ssl._create_unverified_context(
+                protocol=ssl.PROTOCOL_TLS_SERVER,
+                cert_reqs=ssl.CERT_OPTIONAL,
+                check_hostname=False,
+                purpose=ssl.Purpose.CLIENT_AUTH,
+                certfile=HttpsTestServerLayer.CERT_FILE,
+                keyfile=HttpsTestServerLayer.CERT_FILE,
+                cafile=HttpsTestServerLayer.CACERT_FILE)
+
+            # Set minimum protocol version, TLSv1 and TLSv1.1 are unsafe.
+            context.minimum_version = ssl.TLSVersion.TLSv1_2
+
+            # Wrap TLS encryption around socket.
+            socket, client_address = HTTPServer.get_request(self)
+            socket = context.wrap_socket(socket, server_side=True)
+
+            return socket, client_address
+
+    class HttpsHandler(BaseHTTPRequestHandler):
+
+        payload = json.dumps({"name": "test", "status": 200, })
+
+        def do_GET(self):
+            self.send_response(200)
+            payload = self.payload.encode('UTF-8')
+            self.send_header("Content-Length", len(payload))
+            self.send_header("Content-Type", "application/json; charset=UTF-8")
+            self.end_headers()
+            self.wfile.write(payload)
+
+    def setUp(self):
+        self.server = self.HttpsServer(
+            (self.HOST, self.PORT),
+            self.HttpsHandler
+        )
+        thread = threading.Thread(target=self.serve_forever)
+        thread.daemon = True  # quit interpreter when only thread exists
+        thread.start()
+        self.waitForServer()
+
+    def serve_forever(self):
+        print("listening on", self.HOST, self.PORT)
+        self.server.serve_forever()
+        print("server stopped.")
+
+    def tearDown(self):
+        self.server.shutdown()
+        self.server.server_close()
+
+    def isUp(self):
+        """
+        Test if a host is up.
+        """
+        s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+        ex = s.connect_ex((self.HOST, self.PORT))
+        s.close()
+        return ex == 0
+
+    def waitForServer(self, timeout=5):
+        """
+        Wait for the host to be available.
+        """
+        with stopit.ThreadingTimeout(timeout) as to_ctx_mgr:
+            while True:
+                if self.isUp():
+                    break
+                time.sleep(0.001)
+
+        if not to_ctx_mgr:
+            raise TimeoutError("Could not properly start embedded webserver "
+                               "within {} seconds".format(timeout))
+
+
+def setUpWithHttps(test):
+    test.globs['crate_host'] = "https://{0}:{1}".format(
+        HttpsTestServerLayer.HOST, HttpsTestServerLayer.PORT
+    )
+    test.globs['pprint'] = pprint
+    test.globs['print'] = cprint
+
+    test.globs['cacert_valid'] = os.path.abspath(
+        os.path.join(os.path.dirname(__file__), "pki/cacert_valid.pem")
+    )
+    test.globs['cacert_invalid'] = os.path.abspath(
+        os.path.join(os.path.dirname(__file__), "pki/cacert_invalid.pem")
+    )
+    test.globs['clientcert_valid'] = os.path.abspath(
+        os.path.join(os.path.dirname(__file__), "pki/client_valid.pem")
+    )
+    test.globs['clientcert_invalid'] = os.path.abspath(
+        os.path.join(os.path.dirname(__file__), "pki/client_invalid.pem")
+    )
+
+
+def _execute_statements(statements, on_error="ignore"):
+    with connect(crate_host) as conn:
+        cursor = conn.cursor()
+        for stmt in statements:
+            _execute_statement(cursor, stmt, on_error=on_error)
+        cursor.close()
+
+
+def _execute_statement(cursor, stmt, on_error="ignore"):
+    try:
+        cursor.execute(stmt)
+    except Exception:  # pragma: no cover
+        # FIXME: Why does this croak on statements like ``DROP TABLE cities``?
+        # Note: When needing to debug the test environment, you may want to
+        #       enable this logger statement.
+        # log.exception("Executing SQL statement failed")
+        if on_error == "ignore":
+            pass
+        elif on_error == "raise":
+            raise