Check for .heroku/node (#384)

If a user pushes a source tree that already includes .heroku/node, give
a nice warning instead of a crypic error message.

Fixes #371

bin/compile

@@ -18,14 +18,6 @@ BUILD_DIR=${1:-}
 CACHE_DIR=${2:-}
 ENV_DIR=${3:-}
 BP_DIR=$(cd $(dirname ${0:-}); cd ..; pwd)
-
-mkdir -p "$BUILD_DIR/.heroku/node/"
-cd $BUILD_DIR
-export PATH="$BUILD_DIR/.heroku/node/bin:$BUILD_DIR/.heroku/yarn/bin":$PATH
-
-LOG_FILE=$(mktemp -t node-build-log.XXXXX)
-echo "" > "$LOG_FILE"
-
 STDLIB_FILE=$(mktemp -t stdlib.XXXXX)
 BUILDPACK_LOG_FILE=${BUILDPACK_LOG_FILE:-/dev/null}
 
@@ -41,6 +33,11 @@ source $BP_DIR/lib/binaries.sh
 source $BP_DIR/lib/cache.sh
 source $BP_DIR/lib/dependencies.sh
 
+export PATH="$BUILD_DIR/.heroku/node/bin:$BUILD_DIR/.heroku/yarn/bin":$PATH
+
+LOG_FILE=$(mktemp -t node-build-log.XXXXX)
+echo "" > "$LOG_FILE"
+
 ### Handle errors
 
 handle_failure() {
@@ -61,6 +58,8 @@ trap 'handle_failure' ERR
 
 ### Failures that should be caught immediately
 
+fail_dot_heroku "$BUILD_DIR"
+fail_dot_heroku_node "$BUILD_DIR"
 fail_invalid_package_json "$BUILD_DIR"
 warn_prebuilt_modules "$BUILD_DIR"
 warn_missing_package_json "$BUILD_DIR"
@@ -75,6 +74,9 @@ create_env() {
 }
 
 header "Creating runtime environment"
+
+mkdir -p "$BUILD_DIR/.heroku/node/"
+cd $BUILD_DIR
 create_env # can't pipe the whole thing because piping causes subshells, preventing exports
 list_node_config | output "$LOG_FILE"
 

lib/failure.sh

@@ -35,6 +35,34 @@ fail_invalid_package_json() {
   fi
 }
 
+fail_dot_heroku() {
+  if [ -f "${1:-}/.heroku" ]; then
+    header "Build failed"
+    warn "The directory .heroku could not be created
+
+       It looks like a .heroku file is checked into this project.
+       The Node.js buildpack uses the hidden directory .heroku to store
+       binaries like the node runtime and npm. You should remove the
+       .heroku file or ignore it by adding it to .slugignore
+       "
+    exit 1
+  fi
+}
+
+fail_dot_heroku_node() {
+  if [ -f "${1:-}/.heroku/node" ]; then
+    header "Build failed"
+    warn "The directory .heroku/node could not be created
+
+       It looks like a .heroku file is checked into this project.
+       The Node.js buildpack uses the hidden directory .heroku to store
+       binaries like the node runtime and npm. You should remove the
+       .heroku file or ignore it by adding it to .slugignore
+       "
+    exit 1
+  fi
+}
+
 warning() {
   local tip=${1:-}
   local url=${2:-https://devcenter.heroku.com/articles/nodejs-support}

test/fixtures/dot-heroku-collision-2/.heroku/random-file

+This is is in .heroku/ but doesn't conflict with our files

test/fixtures/dot-heroku-collision-2/package.json

+{
+  "name": "node-buildpack-test-app",
+  "version": "0.0.1",
+  "description": "node buildpack integration test app",
+  "repository" : {
+    "type" : "git",
+    "url" : "http://github.com/example/example.git"
+  },
+  "dependencies": {},
+  "engines": {
+    "node": "0.10.29"
+  }
+}

test/fixtures/dot-heroku-collision/.heroku

+This file could be anything!

test/fixtures/dot-heroku-collision/package.json

+{
+  "name": "node-buildpack-test-app",
+  "version": "0.0.1",
+  "description": "node buildpack integration test app",
+  "repository" : {
+    "type" : "git",
+    "url" : "http://github.com/example/example.git"
+  },
+  "dependencies": {},
+  "engines": {
+    "node": "0.10.29"
+  }
+}

test/fixtures/dot-heroku-node-collision/.heroku/node

+Filler file

test/fixtures/dot-heroku-node-collision/package.json

+{
+  "name": "node-buildpack-test-app",
+  "version": "0.0.1",
+  "description": "node buildpack integration test app",
+  "repository" : {
+    "type" : "git",
+    "url" : "http://github.com/example/example.git"
+  },
+  "dependencies": {},
+  "engines": {
+    "node": "0.10.29"
+  }
+}

test/run

@@ -184,6 +184,27 @@ testWarningsOnFailure() {
   assertCapturedError
 }
 
+testDotHerokuCollision() {
+  compile "dot-heroku-collision"
+  assertCaptured "The directory .heroku could not be created"
+  assertCaptured ".heroku file is checked into this project"
+  assertNotCaptured "please submit a ticket"
+  assertCapturedError
+
+  compile "dot-heroku-collision-2"
+  assertCaptured "Build succeeded!"
+  assertNotCaptured ".heroku file is checked into this project"
+  assertCapturedSuccess
+}
+
+testDotHerokuNodeCollision() {
+  compile "dot-heroku-node-collision"
+  assertCaptured "The directory .heroku/node could not be created"
+  assertCaptured ".heroku file is checked into this project"
+  assertNotCaptured "please submit a ticket"
+  assertCapturedError
+}
+
 testMultipleRuns() {
   local compileDir=$(mktmpdir)
   local cacheDir=$(mktmpdir)