From ffbfe2da3d1bdd210d989c848c7b4130b269a5d0 Mon Sep 17 00:00:00 2001
From: James Munnelly <james.munnelly@jetstack.io>
Date: Sat, 4 Nov 2017 00:44:08 +0000
Subject: [PATCH] Use ordered RemoveDuplicates. Add additional test cases.

---
 pkg/util/filter.go       | 18 +++++++++---------
 pkg/util/pki/csr_test.go | 12 ++++++++++++
 2 files changed, 21 insertions(+), 9 deletions(-)

diff --git a/pkg/util/filter.go b/pkg/util/filter.go
index a75eeb171..c4594e8dd 100644
--- a/pkg/util/filter.go
+++ b/pkg/util/filter.go
@@ -57,15 +57,15 @@ func StringFilter(fn FilterFn, in ...string) StringFilterWrapper {
 }
 
 func RemoveDuplicates(in []string) []string {
-	dedupMap := make(map[string]struct{})
+	var found []string
+Outer:
 	for _, i := range in {
-		dedupMap[i] = struct{}{}
+		for _, i2 := range found {
+			if i2 == i {
+				continue Outer
+			}
+		}
+		found = append(found, i)
 	}
-	out := make([]string, len(dedupMap))
-	i := 0
-	for s := range dedupMap {
-		out[i] = s
-		i++
-	}
-	return out
+	return found
 }
diff --git a/pkg/util/pki/csr_test.go b/pkg/util/pki/csr_test.go
index e54274dcc..a6faaa57a 100644
--- a/pkg/util/pki/csr_test.go
+++ b/pkg/util/pki/csr_test.go
@@ -102,6 +102,18 @@ func TestDNSNamesForCertificate(t *testing.T) {
 			crtDNSNames:    []string{"dnsname1", "dnsname2"},
 			expectDNSNames: []string{"dnsname1", "dnsname2"},
 		},
+		{
+			name:           "certificate with dnsName[0] set to equal common name",
+			crtCN:          "cn",
+			crtDNSNames:    []string{"cn", "dnsname"},
+			expectDNSNames: []string{"cn", "dnsname"},
+		},
+		{
+			name:           "certificate with a dnsName equal to cn",
+			crtCN:          "cn",
+			crtDNSNames:    []string{"dnsname", "cn"},
+			expectDNSNames: []string{"cn", "dnsname"},
+		},
 	}
 	testFn := func(test testT) func(*testing.T) {
 		return func(t *testing.T) {