[errors] Remove Fix(), move MultiErrorFromErrors().

common/sync/parallel/multierror_test.go

Index: common/sync/parallel/multierror_test.go
diff --git a/common/sync/parallel/multierror_test.go b/common/sync/parallel/multierror_test.go
new file mode 100644
index 0000000000000000000000000000000000000000..6cb4b64f7dc023d895be58d86ddedbcc846ed528
--- /dev/null
+++ b/common/sync/parallel/multierror_test.go
@@ -0,0 +1,48 @@
+// Copyright 2015 The LUCI Authors. All rights reserved.
+// Use of this source code is governed under the Apache License, Version 2.0
+// that can be found in the LICENSE file.
+
+package parallel
+
+import (
+	"fmt"
+	"testing"
+
+	. "github.com/smartystreets/goconvey/convey"
+)
+
+type otherMEType []error
+
+func (o otherMEType) Error() string { return "FAIL" }
+
+func TestMultiError(t *testing.T) {
+	t.Parallel()
+
+	Convey("MultiError works", t, func() {
+		Convey("multiErrorFromErrors with errors works", func() {
+			mec := make(chan error, 4)
+			mec <- nil
+			mec <- fmt.Errorf("first error")
+			mec <- nil
+			mec <- fmt.Errorf("what")
+			close(mec)
+
+			err := multiErrorFromErrors(mec)
+			So(err.Error(), ShouldEqual, `first error (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, 2)
+			c <- nil
+			c <- nil
+			close(c)
+			So(multiErrorFromErrors(c), ShouldBeNil)
+		})
+	})
+}