CI: use -e install for tox + add docker-compose for isolated Rabbit…

…MQ (#4375)

* Using `pip install -e .` for tox runs improves startup time for tests
   by preventing unnecessary copy of files.

* The docker-compose yml file allows to set up an isolated RabbitMQ
   instance for local CI testing.

.ci/docker-rabbitmq.yml

@@ -0,0 +1,29 @@
+# A small configuration for use in local CI testing,
+# if you wish to control the rabbitmq used.
+
+# Simply install docker, then run:
+# $ docker-compose -f .ci/docker-rabbitmq.yml up -d
+
+# and to power down, after testing:
+# $ docker-compose -f .ci/docker-rabbitmq.yml down
+
+# you can monitor rabbitmq use at: http://localhost:15672
+
+version: '3.4'
+
+services:
+
+  rabbit:
+    image: rabbitmq:3.8.3-management
+    container_name: aiida-rmq
+    environment:
+        RABBITMQ_DEFAULT_USER: guest
+        RABBITMQ_DEFAULT_PASS: guest
+    ports:
+      - '5672:5672'
+      - '15672:15672'
+    healthcheck:
+      test: rabbitmq-diagnostics -q ping
+      interval: 30s
+      timeout: 30s
+      retries: 5

pyproject.toml

@@ -68,6 +68,9 @@ legacy_tox_ini = """
 [tox]
 envlist = py37-django
 
+[testenv]
+usedevelop=True
+
 [testenv:py{36,37,38}-{django,sqla}]
 deps =
     py36: -rrequirements/requirements-py-3.6.txt