user12489: I'd like to do RBF testing on testnet. I'd like to simulate a transaction with too-low fees, aka "stuck" transaction, and then RBF it in various ways.
Problem is, all testnet transactions are added to the next block due to mostly-empty mempool and 1 sat/B fee rate.
Is there a clever way to create a transaction that sits in the testnet mempool, which can be later mined after RBF?
Didn't the developers of RBF test their code on testnet?

user-1: There are 2 workarounds possible:

It takes few minutes for most of the transactions to be included in a block. So, you can prepare all the steps in advance and perform within couple of minutes before this transaction is confirmed.

Broadcast transactions with fee rate below 1 sat/vByte


Change Min Transaction Relay Fee in bitcoin.conf with minrelaytxfee=0.00000001
Either run multiple nodes on testnet with same configuration and add them using addnode or ignore this step.
Create a transaction with createrawtransaction, Enable RBF and specify fee rate below 1 sat/vByte with arguments "replaceable" : true and "fee_rate" : 0.5 in fundrawtransaction
Sign the transaction with signrawtransactionwithwallet
Broadcast the transaction with sendrawtransaction
Check the transaction details using https://chain.so/testnet/btc

Bump fee: bumpfee 42bb96fa5f5812cfd53695f679b69bccaf37fb4d49b78a650e05e0109d92f223
{
  "txid": "bac13170082c79033d37767e9180d676b05044acf90e41b1a992f76eda97f14e",
  "origfee": 0.00000526,
  "fee": 0.00005616,
  "errors": [
  ]
}


12489: <p>I'd like to do RBF testing on testnet. I'd like to simulate a transaction with too-low fees, aka &quot;stuck&quot; transaction, and then RBF it in various ways.</p>
<p>Problem is, all testnet transactions are added to the next block due to mostly-empty mempool and 1 sat/B fee rate.</p>
<p>Is there a clever way to create a transaction that sits in the testnet mempool, which can be later mined after RBF?</p>
<p>Didn't the developers of RBF test their code on testnet?</p>
 -1: <p>There are 2 workarounds possible:</p>
<ol>
<li><p>It takes few minutes for most of the transactions to be included in a block. So, you can prepare all the steps in advance and perform within couple of minutes before this transaction is confirmed.</p>
</li>
<li><p>Broadcast transactions with fee rate below 1 sat/vByte</p>
</li>
</ol>
<p>Change Min Transaction Relay Fee in <code>bitcoin.conf</code> with <code>minrelaytxfee=0.00000001</code></p>
<p>Either run multiple nodes on testnet with same configuration and add them using <code>addnode</code> or ignore this step.</p>
<p>Create a transaction with <code>createrawtransaction</code>, Enable RBF and specify fee rate below 1 sat/vByte with arguments <code>&quot;replaceable&quot; : true</code> and <code>&quot;fee_rate&quot; : 0.5</code> in <code>fundrawtransaction</code></p>
<p>Sign the transaction with <code>signrawtransactionwithwallet</code></p>
<p>Broadcast the transaction with <code>sendrawtransaction</code></p>
<p>Check the transaction details using <a href="https://chain.so/testnet/btc" rel="nofollow noreferrer">https://chain.so/testnet/btc</a></p>
<p><a href="https://i.stack.imgur.com/7vVKU.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/7vVKU.png" alt="sochain-explorer" /></a></p>
<p>Bump fee: <code>bumpfee 42bb96fa5f5812cfd53695f679b69bccaf37fb4d49b78a650e05e0109d92f223</code></p>
<pre><code>{
  &quot;txid&quot;: &quot;bac13170082c79033d37767e9180d676b05044acf90e41b1a992f76eda97f14e&quot;,
  &quot;origfee&quot;: 0.00000526,
  &quot;fee&quot;: 0.00005616,
  &quot;errors&quot;: [
  ]
}
</code></pre>
