Add test for stream package

stream/stream_test.go

@@ -0,0 +1,27 @@
+package stream
+
+import "testing"
+
+type fakePRNG struct{}
+
+func (*fakePRNG) Uint64() uint64 {
+	return uint64(0XDEADBEEF)
+}
+
+func TestStreamCipher(t *testing.T) {
+	plaintext := []byte("hello, world")
+
+	ciphertext := make([]byte, len(plaintext))
+	c1 := NewCipher(new(fakePRNG))
+	c1.XORKeyStream(ciphertext, plaintext)
+
+	plaintext2 := make([]byte, len(plaintext))
+	c2 := NewCipher(new(fakePRNG))
+	c2.XORKeyStream(plaintext2, ciphertext)
+
+	for i, v := range plaintext2 {
+		if v != plaintext[i] {
+			t.Fatalf("mismatch at byte %d:\nhave: % x\nwant: % x", i, plaintext2, plaintext)
+		}
+	}
+}