add tests around creating a default Procfile

bin/compile

@@ -80,14 +80,15 @@ status "Cleaning up node-gyp and npm artifacts"
 rm -rf "$build_dir/.node-gyp"
 rm -rf "$build_dir/.npm"
 
-# Add npm start to Procfile if necessary
+# If Procfile is absent, try to create one using `npm start`
 if [ ! -e $build_dir/Procfile ]; then
   npm_start=$(cat $build_dir/package.json | $bp_dir/vendor/jq -r .scripts.start)
 
-  # If a start script is declared, add it to a Procfile
-  if [ "$npm_start" != "null" ]; then
-    status "No Procfile present; adding npm start script to Procfile"
-    echo "web: $npm_start" > $build_dir/Procfile
+  if [ "$npm_start" == "null" ]; then
+    protip "Create a Procfile or specify a start script in package.json"
+  else
+    status "No Procfile found; adding npm start script to Procfile"
+    echo "web: npm start" > $build_dir/Procfile
   fi
 fi
 

bin/test

@@ -91,6 +91,19 @@ testUserConfig() {
   assertCapturedError 1 ""
 }
 
+testProcfileAbsentNpmStartPresent() {
+  compile "procfile-absent-npm-start-present"
+  assertCaptured "No Procfile found; adding npm start script to Procfile"
+  assertFile "web: npm start" "Procfile"
+  assertCapturedSuccess
+}
+
+testProcfileAbsentNpmStartAbsent() {
+  compile "procfile-absent-npm-start-absent"
+  assertCaptured "Create a Procfile or specify a start script"
+  assertCapturedSuccess
+}
+
 # Pending Tests
 
 # testNodeBinariesAddedToPath() {

test/procfile-absent-npm-start-absent/README.md

+A fake README, to keep npm from polluting stderr.
\ No newline at end of file

test/procfile-absent-npm-start-absent/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": {
+    "hashish": "*"
+  },
+  "engines": {
+    "node": "~0.10.0"
+  }
+}

test/procfile-absent-npm-start-present/README.md

+A fake README, to keep npm from polluting stderr.
\ No newline at end of file

test/procfile-absent-npm-start-present/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": {
+    "hashish": "*"
+  },
+  "engines": {
+    "node": "~0.10.0"
+  },
+  "scripts": {
+    "start": "echo foo"
+  }
+}