add contains to util

util/util.go

diff --git a/util/util.go b/util/util.go
index 8eeb709..65435ba 100644
--- a/util/util.go
+++ b/util/util.go
@@ -116,3 +116,13 @@
 		}
 	}
 }
+
+// Contains return whether the target string is found in the slice.
+func Contains(slice []string, target string) bool {
+	for _, s := range slice {
+		if s == target {
+			return true
+		}
+	}
+	return false
+}

util/util_test.go

diff --git a/util/util_test.go b/util/util_test.go
index da1c714..d4b7b27 100644
--- a/util/util_test.go
+++ b/util/util_test.go
@@ -204,4 +204,11 @@
 			}
 		}, 2)
 	})
+
+	It("Contains", func() {
+		Expect(util.Contains([]string{"foo", "bar"}, "foo")).Should(BeTrue())
+		Expect(util.Contains([]string{"foo", "bar"}, "bar")).Should(BeTrue())
+		Expect(util.Contains([]string{"foo", "bar"}, "xxx")).Should(BeFalse())
+		Expect(util.Contains([]string{}, "foo")).Should(BeFalse())
+	})
 })