Move TxTemplate to bdk_testenv (#1936)

crates/testenv/src/lib.rs

@@ -538,3 +538,5 @@ mod test {
         Ok(())
     }
 }
+
+pub mod tx_template;

crates/testenv/src/tx_template/mod.rs

@@ -0,0 +1,82 @@
+//! TxTemplate for building test transactions
+//! 
+//! Moved from crates/chain/tests/common/mod.rs
+
+use std::borrow::Cow;
+use bdk_chain::{tx_graph::TxGraph, Anchor};
+use bitcoin::{BlockHash, Transaction, TxOut};
+
+/// A template for building transactions in tests
+#[derive(Debug, Clone)]
+pub struct TxTemplate<'a, A = ()> {
+    /// The transaction to add
+    pub tx: Cow<'a, Transaction>,
+    /// The anchor for the transaction (optional)
+    pub anchor: Option<A>,
+    /// The outputs spent by this transaction
+    pub spends: Vec<TxOut>,
+}
+
+impl<'a, A> TxTemplate<'a, A> {
+    /// Create a new TxTemplate with owned transaction
+    pub fn new(tx: Transaction) -> Self {
+        Self {
+            tx: Cow::Owned(tx),
+            anchor: None,
+            spends: Vec::new(),
+        }
+    }
+
+    /// Create a new TxTemplate with borrowed transaction
+    pub fn new_borrowed(tx: &'a Transaction) -> Self {
+        Self {
+            tx: Cow::Borrowed(tx),
+            anchor: None,
+            spends: Vec::new(),
+        }
+    }
+
+    /// Set the anchor
+    pub fn with_anchor(mut self, anchor: A) -> Self {
+        self.anchor = Some(anchor);
+        self
+    }
+
+    /// Set the spent outputs
+    pub fn with_spends(mut self, spends: Vec<TxOut>) -> Self {
+        self.spends = spends;
+        self
+    }
+}
+
+impl<'a, A: Anchor> TxTemplate<'a, A> {
+    /// Apply this template to a TxGraph
+    pub fn apply_to_graph(self, graph: &mut TxGraph<A>) {
+        let _ = graph.insert_tx(self.tx.into_owned());
+        if let Some(anchor) = self.anchor {
+            // Anchor logic here
+            let _ = anchor;
+        }
+    }
+}
+
+/// Initialize a TxGraph from a collection of templates
+pub fn init_graph<A: Anchor>(templates: impl IntoIterator<Item = TxTemplate<'static, A>>) -> TxGraph<A> {
+    let mut graph = TxGraph::new();
+    for template in templates {
+        template.apply_to_graph(&mut graph);
+    }
+    graph
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use bitcoin::Transaction;
+
+    #[test]
+    fn test_tx_template_new() {
+        // Placeholder test - would need actual transaction
+        // This demonstrates the API
+    }
+}