Drop yarn-native-cache feature (#1004)

* Drop yarn-native-cache feature

* Drop fixture feature setting

* Drop yarn-native-cache feature

* Update test expectations: it was testing an impossible scenario

* Add changelog entry for feature flag removal

CHANGELOG.md

@@ -1,6 +1,7 @@
 # Node.js Buildpack Changelog
 
 ## main
+- Drop the `yarn-native-cache` feature flag ([#1004](https://github.com/heroku/heroku-buildpack-nodejs/pull/1004))
 
 ## v196 (2022-05-31)
 - Add metrics plugin for Node 17 and 18 ([#1002](https://github.com/heroku/heroku-buildpack-nodejs/pull/1002))

bin/compile

@@ -192,8 +192,6 @@ fi
 [ ! "$NPM_CONFIG_CACHE" ] && NPM_CONFIG_CACHE=$(mktemp -d -t npmcache.XXXXX)
 export YARN_CACHE_FOLDER NPM_CONFIG_CACHE
 
-[[ $(features_get "cache-native-yarn-cache") == "false" ]] && USE_YARN_CACHE=false
-
 if [[ -z "$USE_NPM_INSTALL" ]] && [[ $(features_get_with_blank "use-npm-ci") == "false" ]]; then
   USE_NPM_INSTALL=true
 fi

features

@@ -1 +0,0 @@
-cache-native-yarn-cache=100

lib/cache.sh

@@ -49,7 +49,7 @@ restore_default_cache_directories() {
   local cache_dir=${2:-}
   local yarn_cache_dir=${3:-}
 
-  if [[ $(features_get "cache-native-yarn-cache") == "true" ]] && [[ "$YARN" == "true" ]]; then
+  if [[ "$YARN" == "true" ]]; then
     if has_yarn_cache "$build_dir"; then
       echo "- yarn cache is checked into source control and cannot be cached"
     elif [[ -e "$cache_dir/node/cache/yarn" ]]; then
@@ -121,7 +121,7 @@ save_default_cache_directories() {
   local cache_dir=${2:-}
   local yarn_cache_dir=${3:-}
 
-  if [[ $(features_get "cache-native-yarn-cache") == "true" ]] && [[ "$YARN" == "true" ]]; then
+  if [[ "$YARN" == "true" ]]; then
     if [[ -d "$yarn_cache_dir" ]]; then
       if [[ "$YARN_2" == "true" ]] && ! node_modules_enabled "$BUILD_DIR"; then
         cp -RTf "$yarn_cache_dir" "$cache_dir/node/cache/yarn"

test/run

@@ -253,23 +253,13 @@ testYarn() {
   assertCapturedSuccess
 }
 
-testYarnCacheDirectory() {
+testYarnCache() {
   local cache=$(mktmpdir)
-  local env_dir=$(mktmpdir)
-  local cache_dir=$(mktmpdir)
-  echo "${cache_dir}/yarn"> "$env_dir/YARN_CACHE_FOLDER"
-  compile "yarn" $cache $env_dir
-  # These will be created if yarn is using the directory for its cache
 
-  assertDirectoryExists ${cache_dir}/yarn
-  # yarn frequently bumps the version number used in its cache
-  # so use a wildcard here to prevent frequent CI failures
-
-  # assert that the above ls command exited successfully, which only happens if the file exists
-  assertEquals "0" "$?"
+  compile "yarn" $cache
 
   # assert that devDependencies are cached
-  assertEquals "1" "$(ls -1 $cache/node/cache/node_modules | grep -c debug | tr -d ' ')"
+  assertEquals "1" "$(ls -1 $cache/node/cache/yarn/v6 | grep -c debug | tr -d ' ')"
 
   assertCapturedSuccess
 }
@@ -286,20 +276,6 @@ testYarnNativeCache() {
   assertCapturedSuccess
 }
 
-testYarnNativeCacheFalse() {
-  local cache=$(mktmpdir)
-
-  compile "yarn-native-cache-false" $cache
-  # These will be created if yarn is using the directory for its cache
-
-  # Run this again with a cache
-  compile "yarn-native-cache-false" $cache
-
-  # assert that devDependencies are not cached
-  assertEquals "1" "$(ls -1 $cache/node/cache/node_modules | grep -c debug | tr -d ' ')"
-  assertCapturedSuccess
-}
-
 testNpm5CacheDirectory() {
   local cache=$(mktmpdir)
   local env_dir=$(mktmpdir)