1 files changed, 24 insertions, 0 deletions
diff --git a/helpers/general.go b/helpers/general.go
index 731452d9d..2237125d7 100644
--- a/helpers/general.go
+++ b/helpers/general.go
@@ -467,3 +467,27 @@ func NormalizeHugoFlags(f *pflag.FlagSet, name string) pflag.NormalizedName {
 	}
 	return pflag.NormalizedName(name)
 }
+
+// DiffStringSlices returns the difference between two string slices.
+// Useful in tests.
+// See:
+// http://stackoverflow.com/questions/19374219/how-to-find-the-difference-between-two-slices-of-strings-in-golang
+func DiffStringSlices(slice1 []string, slice2 []string) []string {
+	diffStr := []string{}
+	m := map[string]int{}
+
+	for _, s1Val := range slice1 {
+		m[s1Val] = 1
+	}
+	for _, s2Val := range slice2 {
+		m[s2Val] = m[s2Val] + 1
+	}
+
+	for mKey, mVal := range m {
+		if mVal == 1 {
+			diffStr = append(diffStr, mKey)
+		}
+	}
+
+	return diffStr
+}