Change the way how tests fail on stderr output.

Wait whole message from stderr output and only after that throw error. This helps to get whole picture why test fails.

test/tap/prepublish.js

@@ -58,16 +58,21 @@ test('test', function (t) {
     env: env
   })
   child.stdout.setEncoding('utf8')
-  child.stderr.on('data', function(chunk) {
-    throw new Error('got stderr data: ' + JSON.stringify('' + chunk))
-  })
+  child.stderr.on('data', onerr)
   child.stdout.on('data', ondata)
   child.on('close', onend)
   var c = ''
+    , e = ''
   function ondata (chunk) {
     c += chunk
   }
+  function onerr (chunk) {
+    e += chunk
+  }
   function onend () {
+    if (e) {
+      throw new Error('got stderr data: ' + JSON.stringify('' + e))
+    }
     c = c.trim()
     var regex = new RegExp("" +
       "> npm-test-prepublish@1.2.5 prepublish [^\\r\\n]+\\r?\\n" +

test/tap/startstop.js

@@ -12,13 +12,14 @@ var common = require('../common-tap')
 
 function run (command, t, parse) {
   var c = ''
+    , e = ''
     , node = process.execPath
     , child = spawn(node, [npm, command], {
       cwd: pkg
     })
 
     child.stderr.on('data', function (chunk) {
-      throw new Error('npm ' + command + ' stderr: ' + chunk.toString())
+      e += chunk
     })
 
     child.stdout.on('data', function (chunk) {
@@ -26,6 +27,9 @@ function run (command, t, parse) {
     })
 
     child.stdout.on('end', function () {
+      if (e) {
+        throw new Error('npm ' + command + ' stderr: ' + e.toString())
+      }
       if (parse) {
         // custom parsing function
         c = parse(c)