Run tests Docker in Docker (#261)

* Try running tests in Docker

* Spawn new container for each test

* Store test artifacts outside of mount

* When requested, build up to date image in test script

* sudo is unneccessary in containerized test env

* Skip azure test

* Backdate fixture file in JSON database

* Pin versions for azure tools

* Mount temp volume for /var/lib/docker to prevent dangling ones created by VOLUME instruction

* Fail backdating tests with message

* Add some documentation on test setup

* Cache images

* Run compose stacks with shortened default timeout

test/ignore/run.sh

@@ -6,23 +6,21 @@ cd $(dirname $0)
 . ../util.sh
 current_test=$(basename $(pwd))
 
-mkdir -p local
+export LOCAL_DIR=$(mktemp -d)
 
 docker compose up -d --quiet-pull
 sleep 5
 docker compose exec backup backup
 
-docker compose down --volumes
+TMP_DIR=$(mktemp -d)
+tar --same-owner -xvf "$LOCAL_DIR/test.tar.gz" -C "$TMP_DIR"
 
-out=$(mktemp -d)
-sudo tar --same-owner -xvf ./local/test.tar.gz -C "$out"
-
-if [ ! -f "$out/backup/data/me.txt" ]; then
+if [ ! -f "$TMP_DIR/backup/data/me.txt" ]; then
   fail "Expected file was not found."
 fi
 pass "Expected file was found."
 
-if [ -f "$out/backup/data/skip.me" ]; then
+if [ -f "$TMP_DIR/backup/data/skip.me" ]; then
   fail "Ignored file was found."
 fi
 pass "Ignored file was not found."