test/system: speed up podman ps --external

The buildah buil kill trick is bad as we have to sleep and wait to aboid
flakes which takes time. Instead it is possible to redo this build part
manually with buildah commands. It is not trival and harder to
understand but it safes 2-3s so I think it is worth it.

Signed-off-by: Paul Holzinger <pholzing@redhat.com>

test/system/040-ps.bats

@@ -142,25 +142,38 @@ load helpers
     run_podman ps --external
     is "${#lines[@]}" "1" "setup check: no storage containers at start of test"
 
-    # Force a buildah timeout; this leaves a buildah container behind
-    local t0=$SECONDS
-    PODMAN_TIMEOUT=5 run_podman 124 build -t thiswillneverexist - <<EOF
-FROM $IMAGE
-RUN touch /intermediate.image.to.be.pruned
-RUN sleep 30
-EOF
-    local t1=$SECONDS
-    local delta_t=$((t1 - t0))
-    assert $delta_t -le 10 \
-           "podman build did not get killed within 10 seconds"
+    # Ok this here is basically a way to reproduce a "leaked" podman build buildah
+    # container without having to kill any process and usage of sleep.
+    run buildah from $IMAGE
+    assert "$status" -eq 0 "buildah from successfully"
+    buildah_cid="$output"
+
+    # Commit new image so we have something to prune.
+    run buildah commit $buildah_cid
+    assert "$status" -eq 0 "buildah commit successfully"
+    buildah_image_id="${lines[-1]}"
+
+    # Create new buildah container with new image so that one can be pruned directly.
+    run buildah from "$buildah_image_id"
+    assert "$status" -eq 0 "buildah from new buildah image successfully"
+
+    # We have to mount the container to trigger the "container .* is mounted" check below.
+    local unshare=
+    if is_rootless; then
+        # rootless needs unshare for mounting
+        unshare="buildah unshare"
+    fi
+    run $unshare buildah mount "$buildah_cid"
+    assert "$status" -eq 0 "buildah mount container successfully"
 
     run_podman ps -a
     is "${#lines[@]}" "1" "podman ps -a does not see buildah containers"
 
     run_podman ps --external
     is "${#lines[@]}" "3" "podman ps -a --external sees buildah containers"
+    # output can include "second ago" or "seconds ago" depending on the timing so match both
     is "${lines[1]}" \
-       "[0-9a-f]\{12\} \+$IMAGE *buildah .* seconds ago .* Storage .* ${PODMAN_TEST_IMAGE_NAME}-working-container" \
+       "[0-9a-f]\{12\} \+$IMAGE *buildah .* seconds\? ago .* Storage .* ${PODMAN_TEST_IMAGE_NAME}-working-container" \
        "podman ps --external"
 
     # 'rm -a' should be a NOP