From 59a2403e2802d27c51f2d30b5f8e1ed9f813dfcc Mon Sep 17 00:00:00 2001
From: Daniela Brozzoni <danielabrozzoni@protonmail.com>
Date: Fri, 29 Sep 2023 15:43:48 +0200
Subject: [PATCH] test(chain): Introduce TxTemplate

Co-authored-by: Wei Chen <wzc110@gmail.com>
---
 crates/chain/tests/common/mod.rs         |   3 +
 crates/chain/tests/common/tx_template.rs | 136 +++++++++++++++++++++++
 2 files changed, 139 insertions(+)
 create mode 100644 crates/chain/tests/common/tx_template.rs

diff --git a/crates/chain/tests/common/mod.rs b/crates/chain/tests/common/mod.rs
index 694d90dc..d3db8191 100644
--- a/crates/chain/tests/common/mod.rs
+++ b/crates/chain/tests/common/mod.rs
@@ -1,3 +1,6 @@
+mod tx_template;
+pub use tx_template::*;
+
 #[allow(unused_macros)]
 macro_rules! block_id {
     ($height:expr, $hash:literal) => {{
diff --git a/crates/chain/tests/common/tx_template.rs b/crates/chain/tests/common/tx_template.rs
new file mode 100644
index 00000000..605a0ba7
--- /dev/null
+++ b/crates/chain/tests/common/tx_template.rs
@@ -0,0 +1,136 @@
+use rand::distributions::{Alphanumeric, DistString};
+use std::collections::HashMap;
+
+use bdk_chain::{tx_graph::TxGraph, BlockId, SpkTxOutIndex};
+use bitcoin::{
+    locktime::absolute::LockTime, secp256k1::Secp256k1, OutPoint, ScriptBuf, Sequence, Transaction,
+    TxIn, TxOut, Txid, Witness,
+};
+use miniscript::Descriptor;
+
+/// Template for creating a transaction in `TxGraph`.
+///
+/// The incentive for transaction templates is to create a transaction history in a simple manner to
+/// avoid having to explicitly hash previous transactions to form previous outpoints of later
+/// transactions.
+#[derive(Clone, Copy, Default)]
+pub struct TxTemplate<'a, A> {
+    /// Uniquely identifies the transaction, before it can have a txid.
+    pub tx_name: &'a str,
+    pub inputs: &'a [TxInTemplate<'a>],
+    pub outputs: &'a [TxOutTemplate],
+    pub anchors: &'a [A],
+    pub last_seen: Option<u64>,
+}
+
+#[allow(dead_code)]
+pub enum TxInTemplate<'a> {
+    /// This will give a random txid and vout.
+    Bogus,
+
+    /// This is used for coinbase transactions because they do not have previous outputs.
+    Coinbase,
+
+    /// Contains the `tx_name` and `vout` that we are spending. The rule is that we must only spend
+    /// from tx of a previous `TxTemplate`.
+    PrevTx(&'a str, usize),
+}
+
+pub struct TxOutTemplate {
+    pub value: u64,
+    pub spk_index: Option<u32>, // some = get spk from SpkTxOutIndex, none = random spk
+}
+
+#[allow(unused)]
+impl TxOutTemplate {
+    pub fn new(value: u64, spk_index: Option<u32>) -> Self {
+        TxOutTemplate { value, spk_index }
+    }
+}
+
+#[allow(dead_code)]
+pub fn init_graph<'a>(
+    tx_templates: impl IntoIterator<Item = &'a TxTemplate<'a, BlockId>>,
+) -> (TxGraph<BlockId>, SpkTxOutIndex<u32>, HashMap<&'a str, Txid>) {
+    let (descriptor, _) = Descriptor::parse_descriptor(&Secp256k1::signing_only(), "tr(tprv8ZgxMBicQKsPd3krDUsBAmtnRsK3rb8u5yi1zhQgMhF1tR8MW7xfE4rnrbbsrbPR52e7rKapu6ztw1jXveJSCGHEriUGZV7mCe88duLp5pj/86'/1'/0'/0/*)").unwrap();
+    let mut graph = TxGraph::<BlockId>::default();
+    let mut spk_index = SpkTxOutIndex::default();
+    (0..10).for_each(|index| {
+        spk_index.insert_spk(
+            index,
+            descriptor
+                .at_derivation_index(index)
+                .unwrap()
+                .script_pubkey(),
+        );
+    });
+    let mut tx_ids = HashMap::<&'a str, Txid>::new();
+
+    for (bogus_txin_vout, tx_tmp) in tx_templates.into_iter().enumerate() {
+        let tx = Transaction {
+            version: 0,
+            lock_time: LockTime::ZERO,
+            input: tx_tmp
+                .inputs
+                .iter()
+                .map(|input| match input {
+                    TxInTemplate::Bogus => TxIn {
+                        previous_output: OutPoint::new(
+                            bitcoin::hashes::Hash::hash(
+                                Alphanumeric
+                                    .sample_string(&mut rand::thread_rng(), 20)
+                                    .as_bytes(),
+                            ),
+                            bogus_txin_vout as u32,
+                        ),
+                        script_sig: ScriptBuf::new(),
+                        sequence: Sequence::default(),
+                        witness: Witness::new(),
+                    },
+                    TxInTemplate::Coinbase => TxIn {
+                        previous_output: OutPoint::null(),
+                        script_sig: ScriptBuf::new(),
+                        sequence: Sequence::MAX,
+                        witness: Witness::new(),
+                    },
+                    TxInTemplate::PrevTx(prev_name, prev_vout) => {
+                        let prev_txid = tx_ids.get(prev_name).expect(
+                            "txin template must spend from tx of template that comes before",
+                        );
+                        TxIn {
+                            previous_output: OutPoint::new(*prev_txid, *prev_vout as _),
+                            script_sig: ScriptBuf::new(),
+                            sequence: Sequence::default(),
+                            witness: Witness::new(),
+                        }
+                    }
+                })
+                .collect(),
+            output: tx_tmp
+                .outputs
+                .iter()
+                .map(|output| match &output.spk_index {
+                    None => TxOut {
+                        value: output.value,
+                        script_pubkey: ScriptBuf::new(),
+                    },
+                    Some(index) => TxOut {
+                        value: output.value,
+                        script_pubkey: spk_index.spk_at_index(index).unwrap().to_owned(),
+                    },
+                })
+                .collect(),
+        };
+
+        tx_ids.insert(tx_tmp.tx_name, tx.txid());
+        spk_index.scan(&tx);
+        let _ = graph.insert_tx(tx.clone());
+        for anchor in tx_tmp.anchors.iter() {
+            let _ = graph.insert_anchor(tx.txid(), *anchor);
+        }
+        if let Some(seen_at) = tx_tmp.last_seen {
+            let _ = graph.insert_seen_at(tx.txid(), seen_at);
+        }
+    }
+    (graph, spk_index, tx_ids)
+}