Where to get a `BIP32 test pubkey` I would like to create a gateway on MyCelium.com. This is for my testing, so I want to test it out first. But I struggle in getting a BIP32 test pubkey.



There is no documentation on MyCelium.com, neither even Google. It is really frustrating to go through this. Could anybody please help? Thanks.
You can use http://bip32.org/, there is a selection box in the top right hand corner of the page to choose Bitcoin Testnet. That will generate you an extended private key from a passphrase of your choosing. Note that I recommend you Do NOT use any keys generated from websites online for real world payments. But for testing this out it should be fine. Using the default passphrase it generated me:
tprv8ZgxMBicQKsPd7Uf69XL1XwhmjHopUGep8GuEiJDZmbQz6o58LninorQAfcKZWARbtRtfnLcJ5MQ2AtHcQJCCRUcMRvmDUjyEmNUWwx8UbK

Once you have generated an extended private key at the top, starting with tprv, you can then select "Info: m" in the Derivation Path box, which will show you the extended public master key. In this case it generated:
tpubD6NzVbkrYhZ4WaWSyoBvQwbpLkojyoTZPRsgXELWz3Popb3qkjcJyJUGLnL4qHHoQvao8ESaAstxYSnhyswJ76uZPStJRJCTKvosUCJZL5B

Again feel free to use this for testing, but please generate an extended key correctly for the mainnet in a secure way, do not use random websites to do it!