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/have_suffix_matcher.go

@@ -0,0 +1,36 @@
+package matchers
+
+import (
+	"fmt"
+
+	"github.com/onsi/gomega/format"
+)
+
+type HaveSuffixMatcher struct {
+	Suffix string
+	Args   []interface{}
+}
+
+func (matcher *HaveSuffixMatcher) Match(actual interface{}) (success bool, err error) {
+	actualString, ok := toString(actual)
+	if !ok {
+		return false, fmt.Errorf("HaveSuffix matcher requires a string or stringer.  Got:\n%s", format.Object(actual, 1))
+	}
+	suffix := matcher.suffix()
+	return len(actualString) >= len(suffix) && actualString[len(actualString)-len(suffix):] == suffix, nil
+}
+
+func (matcher *HaveSuffixMatcher) suffix() string {
+	if len(matcher.Args) > 0 {
+		return fmt.Sprintf(matcher.Suffix, matcher.Args...)
+	}
+	return matcher.Suffix
+}
+
+func (matcher *HaveSuffixMatcher) FailureMessage(actual interface{}) (message string) {
+	return format.Message(actual, "to have suffix", matcher.suffix())
+}
+
+func (matcher *HaveSuffixMatcher) NegatedFailureMessage(actual interface{}) (message string) {
+	return format.Message(actual, "not to have suffix", matcher.suffix())
+}