add django_test suite script for CI

Updates #73

.gitignore

@@ -5,3 +5,4 @@ build/
 .tox/
 MANIFEST
 dist/
+django_tests

.travis.yml

@@ -1,13 +1,19 @@
 language: python
+before_install:
+    - openssl aes-256-cbc -K $encrypted_3bd81e4a6a4c_key -iv $encrypted_3bd81e4a6a4c_iv -in appdev-soda-spanner-staging-b842e628aa41-orijtech.json.enc -out ~/creds.json -d
+
+env:
+    # Reuse an available database to speed up Travis tests lest we can
+    # get terminations as the underlying tables are created.
+    - GOOGLE_APPLICATION_CREDENTIALS=~/creds.json RUNNING_SPANNER_BACKEND_TESTS=1 DJANGO_TEST_APPS="basic" SPANNER_TEST_DB=travisdb1 SPANNER_DROP_DB_ON_EXIT=false
+
 python:
-    - "3.5"
-    - "3.6"
     - "3.7"
-    - "3.8"
 cache: pip
 install:
     - pip install . tox-travis flake8 isort
 script:
     - tox
     - flake8
     - isort --recursive --check-only --diff
+    - bash django_test_suite.sh

django_test_suite.sh

@@ -0,0 +1,108 @@
+#!/bin/sh
+
+ORIGWD=$(pwd)
+# If no SPANNER_TEST_DB is set, generate a unique one
+# so that we can have multiple tests running without
+# conflicting which changes and constraints. We'll always
+# cleanup the created database.
+TEST_DBNAME=${SPANNER_TEST_DB:-testdb-$(date +%F%H%M%S)}
+TEST_APPS=${DJANGO_TEST_APPS:-basic}
+INSTANCE_NAME=${SPANNER_TEST_INSTANCE:-django-tests}
+PROJECT=${SPANNER_TEST_PROJECT:-appdev-soda-spanner-staging}
+SETTINGS_FILE="$TEST_DBNAME-settings"
+DROPDB_ON_EXIT=${SPANNER_DROP_DB_ON_EXIT:-true}
+
+function create_db() {
+    echo "
+from google.cloud import spanner_v1 as sp
+ins = sp.Client(project='$PROJECT').instance('$INSTANCE_NAME')
+if not ins.exists():
+    ins.configuration_name = 'projects/$PROJECT/instanceConfigs/regional-us-west2'
+    lro = ins.create()
+    _ = lro.result()
+    print('Created instance: $INSTANCE_NAME')
+db = ins.database('$TEST_DBNAME')
+if not db.exists():
+    lro = db.create()
+    _ = lro.result()
+    print('Created database: $TEST_DBNAME')
+else:
+    print('$TEST_DBNAME already exists')
+" | python3 -
+    return $?
+}
+
+function checkout_django() {
+    mkdir -p django_tests && cd django_tests
+    git clone --depth 1 --single-branch --branch spanner-2.2.x https://github.com/timgraham/django.git
+    cd django && pip install -e .
+    return $?
+}
+
+function create_settings() {
+    cat << ! > "$SETTINGS_FILE.py"
+DATABASES = {
+   'default': {
+       'ENGINE': 'spanner.django',
+       'SPANNER_URL': "cloudspanner:/projects/$PROJECT/instances/$INSTANCE_NAME/databases/$TEST_DBNAME?instance_config=projects/$PROJECT/instanceConfigs/regional-us-west2",
+        'TEST': {
+            'NAME': "$TEST_DBNAME",
+        },
+   }
+}
+SECRET_KEY = 'spanner_tests_secret_key'
+PASSWORD_HASHERS = [
+    'django.contrib.auth.hashers.MD5PasswordHasher',
+]
+!
+}
+
+function drop_db() {
+    echo "
+from google.cloud import spanner_v1 as sp
+ins = sp.Client(project='$PROJECT').instance('$INSTANCE_NAME')
+if not ins.exists():
+    print('Instance $INSTANCE_NAME does not exist anyways')
+else:
+    db = ins.database('$TEST_DBNAME')
+    if db.exists():
+        db.drop()
+        print('Dropped $TEST_DBNAME')
+" | python3 -
+    return $?
+}
+
+function run_django_tests() {
+    cd tests
+    create_settings
+    echo -e "\033[32mRunning Django tests $TEST_APPS\033[00m"
+    # Using --keepdb here because Django's test suite tries to invoke `DROP DATABASE`
+    # using the Cursor if --keepdb isn't set, yet only the Spanner.Database instance
+    # can drop the database, which we do manually in function `drop_db`.
+    python3 runtests.py $TEST_APPS --verbosity=2 --keepdb --noinput --settings $SETTINGS_FILE
+    return $?
+}
+
+function install_spanner_django() {
+    pip3 install .
+    return $?
+}
+
+function cleanup_and_exit() {
+    exitCode=$?
+    msg=$1
+    echo $msg
+    if [[ $DROPDB_ON_EXIT = "true" ]]
+    then
+        drop_db
+    fi
+    cd $ORIGWD
+    exit $exitCode
+}
+
+install_spanner_django || cleanup_and_exit
+create_db || cleanup_and_exit "INSTANCE: $INSTANCE_NAME DB: $TEST_DBNAME could not be created"
+checkout_django || cleanup_and_exit
+run_django_tests || cleanup_and_exit
+# Unconditionally clean up before exit.
+cleanup_and_exit