test: Remove golang test runner (#592)

.kokoro/build.sh

@@ -61,7 +61,7 @@ then
     # 'spanner.googleapis.com').
     export DJANGO_WORKER_COUNT=0
 else
-    export DJANGO_WORKER_COUNT=4
+    export DJANGO_WORKER_COUNT=5
 fi
 
-./bin/parallelize_tests_linux
+python3 ./run_testing_worker.py

run_testing_worker.py

@@ -0,0 +1,75 @@
+#!/usr/bin/env python3
+
+# Copyright 2020 Google LLC.
+
+# Use of this source code is governed by a BSD-style
+# license that can be found in the LICENSE file or at
+# https://developers.google.com/open-source/licenses/bsd
+
+import math
+import os
+import random
+import time
+
+from google.cloud.spanner_v1 import Client
+
+REGION = "regional-us-central1"
+
+
+class TestInstance:
+    def __enter__(self):
+        project = os.getenv(
+            "GOOGLE_CLOUD_PROJECT",
+            os.getenv("PROJECT_ID", "emulator-test-project"),
+        )
+
+        client = Client(project=project)
+
+        config = f"{client.project_name}/instanceConfigs/{REGION}"
+
+        name = "spanner-django-test-{}".format(str(int(time.time())))
+
+        self._instance = client.instance(name, config)
+        created_op = self._instance.create()
+        created_op.result(120)  # block until completion
+        return name
+
+    def __exit__(self, exc, exc_value, traceback):
+        self._instance.delete()
+
+
+worker_index = int(os.getenv("DJANGO_WORKER_INDEX", 0))
+worker_count = int(os.getenv("DJANGO_WORKER_COUNT", 1))
+
+if worker_index >= worker_count:
+    print(
+        "worker_index ({wi}) > worker_count ({wc})".format(
+            wi=worker_index, wc=worker_count,
+        )
+    )
+    exit()
+
+with open("django_test_apps.txt", "r") as file:
+    all_apps = file.read().split("\n")
+
+apps_per_worker = math.ceil(len(all_apps) / worker_count)
+
+start_index = min(worker_index * apps_per_worker, len(all_apps))
+end_index = min(start_index + apps_per_worker, len(all_apps))
+
+test_apps = all_apps[start_index:end_index]
+print("test apps: ", test_apps)
+
+if not test_apps:
+    exit()
+
+delay = random.randint(10, 60)
+print("creating instance with delay: {} seconds".format(delay))
+time.sleep(delay)
+
+with TestInstance() as instance_name:
+    os.system(
+        """DJANGO_TEST_APPS="{apps}" SPANNER_TEST_INSTANCE={instance} bash ./django_test_suite.sh""".format(
+            apps=" ".join(test_apps), instance=instance_name
+        )
+    )