add unit test of generation of connection fingerprints

e2e/connectionFingerprint_test.go

+package e2e
+
+import (
+	"bytes"
+	"golang.org/x/crypto/blake2b"
+	"testing"
+)
+
+// Unit test of GenerateConnectionFingerprint.
+func TestGenerateConnectionFingerprint(t *testing.T) {
+	receiveFp := []byte{5}
+	sendFp := []byte{10}
+	h, _ := blake2b.New256(nil)
+	h.Write(append(receiveFp, sendFp...))
+	expected := h.Sum(nil)
+
+	fp := GenerateConnectionFingerprint(sendFp, receiveFp)
+	if !bytes.Equal(fp, expected) {
+		t.Errorf("ConnectionFingerprint did not return the expected "+
+			"fingerprint.\nexpected: %s\nreceived: %s", expected, fp)
+	}
+
+	// Flip the order and show that the output is the same.
+	receiveFp, sendFp = sendFp, receiveFp
+
+	fp = GenerateConnectionFingerprint(sendFp, receiveFp)
+	if !bytes.Equal(fp, expected) {
+		t.Errorf("ConnectionFingerprint did not return the expected "+
+			"fingerprint.\nexpected: %s\nreceived: %s", expected, fp)
+	}
+}