Switch to ginkgo/gomega for tests

This switches over to ginkgo/gomega for tests, which makes writing
certain tests easier/more fluent in the future.

vendor/github.com/onsi/gomega/matchers/be_empty_matcher.go

@@ -0,0 +1,27 @@
+package matchers
+
+import (
+	"fmt"
+
+	"github.com/onsi/gomega/format"
+)
+
+type BeEmptyMatcher struct {
+}
+
+func (matcher *BeEmptyMatcher) Match(actual interface{}) (success bool, err error) {
+	length, ok := lengthOf(actual)
+	if !ok {
+		return false, fmt.Errorf("BeEmpty matcher expects a string/array/map/channel/slice.  Got:\n%s", format.Object(actual, 1))
+	}
+
+	return length == 0, nil
+}
+
+func (matcher *BeEmptyMatcher) FailureMessage(actual interface{}) (message string) {
+	return format.Message(actual, "to be empty")
+}
+
+func (matcher *BeEmptyMatcher) NegatedFailureMessage(actual interface{}) (message string) {
+	return format.Message(actual, "not to be empty")
+}