Enforce validators can only use the correct pubkey type (#2739)

* Enforce validators can only use the correct pubkey type

* adapt to variable renames

* Address comments from #2636

* separate updating and validation logic

* update spec

* Add test case for TestStringSliceEqual, clarify slice copying code

* Address @ebuchman's comments

* Split up testing validator update execution, and its validation

libs/common/string_test.go

@@ -3,6 +3,8 @@ package common
 import (
 	"testing"
 
+	"github.com/stretchr/testify/require"
+
 	"github.com/stretchr/testify/assert"
 )
 
@@ -35,3 +37,22 @@ func TestASCIITrim(t *testing.T) {
 	assert.Equal(t, ASCIITrim(" a "), "a")
 	assert.Panics(t, func() { ASCIITrim("\xC2\xA2") })
 }
+
+func TestStringSliceEqual(t *testing.T) {
+	tests := []struct {
+		a    []string
+		b    []string
+		want bool
+	}{
+		{[]string{"hello", "world"}, []string{"hello", "world"}, true},
+		{[]string{"test"}, []string{"test"}, true},
+		{[]string{"test1"}, []string{"test2"}, false},
+		{[]string{"hello", "world."}, []string{"hello", "world!"}, false},
+		{[]string{"only 1 word"}, []string{"two", "words!"}, false},
+		{[]string{"two", "words!"}, []string{"only 1 word"}, false},
+	}
+	for i, tt := range tests {
+		require.Equal(t, tt.want, StringSliceEqual(tt.a, tt.b),
+			"StringSliceEqual failed on test %d", i)
+	}
+}