Move multierror logic into luci-go.

common/errors/errors_test.go

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package errors
 
 import (
         "fmt"
         "testing"
 
@@ skipping 17 matching lines @@
                 So(err.(*MarkedError).Orig, ShouldEqual, c)
 
                 So(f(nil), ShouldBeNil)
         })
 }
 
 func TestMultiError(t *testing.T) {
         Convey("MultiError works", t, func() {
                 var me error = MultiError{fmt.Errorf("hello"), fmt.Errorf("bob")}
 
-                So(me.Error(), ShouldEqual, `["hello" "bob"]`)
+                So(me.Error(), ShouldEqual, `hello (and 1 other error)`)
 
                 Convey("MultiErrorFromErrors with errors works", func() {
                         mec := make(chan error, 5)
+                        mec <- MakeMarkFn("multiErr")("one-off")
+                        mec <- nil
                         mec <- fmt.Errorf("what")
-                        mec <- nil
-                        mec <- MakeMarkFn("multiErr")("one-off")
                         close(mec)
 
                         err := MultiErrorFromErrors(mec)
-                        So(err.Error(), ShouldEqual, `["what" "multiErr - errors_test.go:44 - one-off"]`)
+                        So(err.Error(), ShouldEqual, `multiErr - errors_test.go:42 - one-off (and 1 other error)`)
                 })
 
                 Convey("MultiErrorFromErrors with nil works", func() {
                         So(MultiErrorFromErrors(nil), ShouldBeNil)
 
                         c := make(chan error)
                         close(c)
                         So(MultiErrorFromErrors(c), ShouldBeNil)
 
                         c = make(chan error, 4)
@@ skipping 31 matching lines @@
         fmt.Printf("got: %s len=%d\n", err, len(err.(MultiError)))
 
         errCh = make(chan error, 10)
         errCh <- nil // and if the channel only has nils
         close(errCh)
 
         err = MultiErrorFromErrors(errCh) // then it returns nil
         fmt.Printf("got: %v\n", err)
 
         // Output:
-        // got: ["what"] len=1
+        // got: what len=1
         // got: <nil>
 }