simplify a bit

bin/compile

@@ -118,15 +118,14 @@ header "Restoring cache"
 restore_cache | output "$LOG_FILE"
 
 build_dependencies() {
-  local has_prebuild_script=$(read_json "$BUILD_DIR/package.json" ".scripts[\"heroku-prebuild\"]")
-  local has_postbuild_script=$(read_json "$BUILD_DIR/package.json" ".scripts[\"heroku-postbuild\"]")
-
+  run_if_present 'heroku-prebuild'
   if $PREBUILD; then
     echo "Prebuild detected (node_modules already exists)"
-    rebuild_node_modules "$BUILD_DIR" "$has_prebuild_script" "$has_postbuild_script"
+    rebuild_node_modules "$BUILD_DIR"
   else
-    install_node_modules "$BUILD_DIR" "$has_prebuild_script" "$has_postbuild_script"
+    install_node_modules "$BUILD_DIR"
   fi
+  run_if_present 'heroku-postbuild'
 }
 
 header "Building dependencies"

lib/dependencies.sh

+run_if_present() {
+  local script_name=${1:-}
+  local has_script=$(read_json "$BUILD_DIR/package.json" ".scripts[\"$script_name\"]")
+  if [ -n "$has_script" ]; then
+    echo "Running $script_name"
+    npm run "$script_name" --if-present
+  fi
+}
+
 install_node_modules() {
   local build_dir=${1:-}
   local has_prebuild_script=${2:-}
@@ -5,10 +14,7 @@ install_node_modules() {
 
   if [ -e $build_dir/package.json ]; then
     cd $build_dir
-    if [ -n "$has_prebuild_script" ]; then
-      echo "Running prebuild script"
-      npm run heroku-prebuild
-    fi
+
     echo "Pruning any extraneous modules"
     npm prune --unsafe-perm --userconfig $build_dir/.npmrc 2>&1
     if [ -e $build_dir/npm-shrinkwrap.json ]; then

test/run

 #!/usr/bin/env bash
 # See README.md for info on running these tests.
 
+testPrePostBuildScripts() {
+  compile "pre-post-build-scripts"
+  assertCaptured "Running heroku-prebuild"
+  assertCaptured "echo heroku-prebuild hook message"
+  assertCaptured "Running heroku-postbuild"
+  assertCaptured "echo heroku-postbuild hook message"
+  assertCapturedSuccess
+
+  compile "stable-node"
+  assertNotCaptured "Running heroku-prebuild"
+  assertNotCaptured "Running heroku-postbuild"
+  assertCapturedSuccess
+}
+
 testWarningsOnFailure() {
   compile "many-warnings"
   assertCaptured "troubleshooting-node-deploys"
@@ -471,15 +485,6 @@ testMultiExport() {
   assertCapturedSuccess
 }
 
-testPrePostBuildScripts() {
-  compile "pre-post-build-scripts"
-  assertCaptured "Running prebuild script"
-  assertCaptured "echo heroku-prebuild hook message"
-  assertCaptured "Running postbuild script"
-  assertCaptured "echo heroku-postbuild hook message"
-  assertCapturedSuccess
-}
-
 # Utils
 
 pushd $(dirname 0) >/dev/null