var bufLens … var bufCap … type MakeStream … // TestStream performs a set of tests on cipher.Stream implementations, // checking the documented requirements of XORKeyStream. func TestStream(t *testing.T, ms MakeStream) { … } // TestStreamFromBlock creates a Stream from a cipher.Block used in a // cipher.BlockMode. It addresses Issue 68377 by checking for a panic when the // BlockMode uses an IV with incorrect length. // For a valid IV, it also runs all TestStream tests on the resulting stream. func TestStreamFromBlock(t *testing.T, block cipher.Block, blockMode func(b cipher.Block, iv []byte) cipher.Stream) { … } func truncateHex(b []byte) string { … }