tests: clean up the test containers

tests/common.bats

@@ -12,24 +12,24 @@ setup() {
   case $BRANCH in
   edge) skip;;
   esac
-  run docker run alpine:$TAG sh -c '. ./etc/os-release; echo ${VERSION_ID%.*}'
+  run docker run --rm alpine:$TAG sh -c '. ./etc/os-release; echo ${VERSION_ID%.*}'
   [ $status -eq 0 ]
   [ "${lines[0]}" = "$VER" ]
 }
 
 @test "package installs cleanly" {
-  run docker run alpine:$TAG apk add --no-cache bash
+  run docker run --rm alpine:$TAG apk add --no-cache bash
   [ $status -eq 0 ]
 }
 
 @test "timezone" {
-  run docker run alpine:$TAG date +%Z
+  run docker run --rm alpine:$TAG date +%Z
   [ $status -eq 0 ]
   [ "$output" = "UTC" ]
 }
 
 @test "repository list is correct" {
-  run docker run alpine:$TAG cat /etc/apk/repositories
+  run docker run --rm alpine:$TAG cat /etc/apk/repositories
   [ $status -eq 0 ]
   [ "${lines[0]}" = "http://dl-cdn.alpinelinux.org/alpine/$BRANCH/main" ]
   [ "${lines[1]}" = "http://dl-cdn.alpinelinux.org/alpine/$BRANCH/community" ]
@@ -37,25 +37,26 @@ setup() {
 }
 
 @test "cache is empty" {
-  run docker run alpine:$TAG sh -c "ls -1 /var/cache/apk | wc -l"
+  run docker run --rm alpine:$TAG sh -c "ls -1 /var/cache/apk | wc -l"
   [ $status -eq 0 ]
   [ "$output" = "0" ]
 }
 
 @test "root password is disabled with default su" {
-  run docker run --user nobody alpine:$TAG su
+  run docker run --rm --user nobody alpine:$TAG su
   [ $status -eq 1 ]
 }
 
 @test "root login is disabled" {
-  run docker run alpine:$TAG awk -F: '$1=="root"{print $2}' /etc/shadow
+  run docker run --rm alpine:$TAG awk -F: '$1=="root"{print $2}' /etc/shadow
   [ $status -eq 0 ]
   [ "$output" = "!" ]
 }
 
 @test "/dev/null should be missing" {
-  run sh -c "docker export $(docker create alpine:$TAG) | tar -t dev/null"
-  [ "$output" != "dev/null" ]
+  container=$(docker create alpine:$TAG)
+  run sh -c "docker export $container | tar -t dev/null"
   [ $status -ne 0 ]
+  docker rm $container
 }