Add an end-to-end automated test that actually integrates with Borg.

tox.ini

@@ -1,20 +1,29 @@
 [tox]
-envlist=py3
-skipsdist=True
+envlist = py3
+skipsdist = True
 
 [testenv]
-usedevelop=True
-deps=-rtest_requirements.txt
+usedevelop = True
+deps = -rtest_requirements.txt
 commands =
-    py.test --cov-report term-missing:skip-covered --cov=borgmatic tests []
+    py.test --cov-report term-missing:skip-covered --cov=borgmatic --ignore=tests/end-to-end \
+        tests []
     black --skip-string-normalization --line-length 100 --check .
     flake8 .
 
 [testenv:black]
-basepython=python3.7
+basepython = python3.7
 commands =
     black --skip-string-normalization --line-length 100 .
 
+[testenv:end-to-end]
+whitelist_externals = docker
+skip_install = true
+deps =
+commands =
+    docker build --file tests/end-to-end/Dockerfile --tag borgmatic-test .
+    docker run --rm borgmatic-test py.test tests/end-to-end []
+
 [flake8]
-ignore=E501,W503
-exclude=*.*/*
+ignore = E501,W503
+exclude = *.*/*