test: derive the docker image tag from the rig inputs

The tag suffix had to be bumped by hand whenever the Dockerfile or
sdk-packages.txt changed; forgetting meant silently testing against
a stale image. Hash the two files into the tag so any edit
invalidates the cache automatically.

1 files changed, 3 insertions, 3 deletions

diff --git a/test b/test
index d6475d6..de6eaf6 100755
--- a/test
+++ b/test
@@ -16,9 +16,9 @@
 set -eu
 
 ROOT="$(cd "$(dirname "$0")" && pwd)"
-# Bump the tag suffix whenever test-rig/Dockerfile or sdk-packages.txt
-# changes; otherwise a stale cached image keeps being used.
-IMG="scrcpy-android-test:5"
+# The image tag is a hash of the rig inputs, so editing the Dockerfile
+# or the SDK package list automatically invalidates the cached image.
+IMG="scrcpy-android-test:$(cat "$ROOT/test-rig/Dockerfile" "$ROOT/test-rig/sdk-packages.txt" | sha256sum | cut -c1-12)"
 
 cmd="${1:-unit}"
 case "$cmd" in