Provide a preconfigured docker command to run tests (DataDog#655)

* [tests] Provide a CLI preconfogure docker command to run tests

* [tests] Base the test runner on a docker compose service

* [tests] Fixed typo in read me

README.md

@@ -46,7 +46,7 @@ launch them through:
 [docker-compose]: https://www.docker.com/products/docker-compose
 
 
-#### Running the Tests
+#### Running the Tests in your local environment
 
 Once docker is up and running you should be able to run the tests. To launch a
 single test manually. For example to run the tests for `redis-py` 2.10 on Python
@@ -61,6 +61,33 @@ To launch the complete test matrix run:
     $ tox
 
 
+#### Running Tests in docker
+
+If you prefer not to setup your local machine to run tests, we provide a preconfigured docker image.
+Note that this image is the same used in CircleCI to run tests.
+
+You still need docker containers running additional services up and running.
+
+Run the test runner
+
+    $ docker-compose run --rm testrunner
+
+Now you are in a bash shell. You can now run tests as you would do in your local environment:
+
+    $ tox -e '{py35,py36}-redis{210}'
+
+If you are in a unix machine, we also provide a shell script to execute commands in the provided container (so you don't
+forget to remove-`--rm` the container after you run it).
+
+For example to run the tests for `redis-py` 2.10 on Python 3.5 and 3.6:
+
+    $ ./scripts/ddtest tox -e '{py35,py36}-redis{210}'
+
+You can also add the `scripts` folder to your path, so then you can run
+
+    $ ddtest tox -e '{py35,py36}-redis{210}'
+
+
 ### Continuous Integration
 
 We use CircleCI 2.0 for our continuous integration.

docker-compose.yml

@@ -78,3 +78,18 @@ services:
           - VP_TEST_DATABASE=docker
         ports:
           - "127.0.0.1:5433:5433"
+
+    testrunner:
+        image: datadog/docker-library:ddtrace_py
+        environment:
+            - TOX_SKIP_DIST=True
+        network_mode: host
+        working_dir: /src
+        volumes:
+            - ./ddtrace:/src/ddtrace:ro
+            - ./tests:/src/tests:ro
+            - ./setup.cfg:/src/setup.cfg:ro
+            - ./setup.py:/src/setup.py:ro
+            - ./tox.ini:/src/tox.ini:ro
+            - ./.ddtox:/src/.tox
+        command: bash

scripts/ddtest

@@ -0,0 +1,5 @@
+#!/usr/bin/env bash
+
+set -e
+
+docker-compose run --rm testrunner $*