Merge pull request #44 from BitGo/BTC-1451.add-descType

feat: add descType method to WrapDescriptor

Author: OttoAllmendinger

packages/wasm-miniscript/src/descriptor.rs

@@ -54,6 +54,15 @@ impl WrapDescriptor {
             _ => Err(JsError::new("Cannot derive from a definite descriptor")),
         }
     }
+    
+    #[wasm_bindgen(js_name = descType)]
+    pub fn desc_type(&self) -> Result<JsValue, JsError> {
+        (match &self.0 {
+            WrapDescriptorEnum::Derivable(desc, _) => desc.desc_type(),
+            WrapDescriptorEnum::Definite(desc) => desc.desc_type(),
+            WrapDescriptorEnum::String(desc) => desc.desc_type(),
+        }).try_to_js_value()
+    }
 
     #[wasm_bindgen(js_name = scriptPubkey)]
     pub fn script_pubkey(&self) -> Result<Vec<u8>, JsError> {

packages/wasm-miniscript/src/try_into_js_value.rs

@@ -1,7 +1,7 @@
 use wasm_bindgen::{JsError, JsValue};
 use js_sys::Array;
 use miniscript::{AbsLockTime, DefiniteDescriptorKey, Descriptor, DescriptorPublicKey, hash256, Miniscript, MiniscriptKey, RelLockTime, ScriptContext, Terminal, Threshold};
-use miniscript::descriptor::{ShInner, SortedMultiVec, TapTree, Tr, WshInner};
+use miniscript::descriptor::{DescriptorType, ShInner, SortedMultiVec, TapTree, Tr, WshInner};
 use miniscript::bitcoin::{PublicKey, XOnlyPublicKey};
 use miniscript::bitcoin::hashes::{hash160, ripemd160};
 use std::sync::Arc;
@@ -245,4 +245,11 @@ impl<Pk: MiniscriptKey + TryIntoJsValue> TryIntoJsValue for Descriptor<Pk> {
             Descriptor::Tr(v) => js_obj!("Tr" => v),
         }
     }
+}
+
+impl TryIntoJsValue for DescriptorType {
+    fn try_to_js_value(&self) -> Result<JsValue, JsError> {
+        let str_from_enum = format!("{:?}", self);
+        Ok(JsValue::from_str(&str_from_enum))
+    }
 }

packages/wasm-miniscript/test/test.ts

@@ -17,6 +17,25 @@ function removeChecksum(descriptor: string): string {
   return parts[0];
 }
 
+function getScriptPubKeyLength(descType: string): number {
+  switch (descType) {
+    case "Wpkh":
+      return 22;
+    case "Sh":
+    case "ShWsh":
+    case "ShWpkh":
+      return 23;
+    case "Pkh":
+      return 25;
+    case "Wsh":
+      return 34;
+    case "Bare":
+      throw new Error("cannot determine scriptPubKey length for Bare descriptor");
+    default:
+      throw new Error("unexpected descriptor type " + descType);
+  }
+}
+
 describe("Descriptor fixtures", function () {
   fixtures.valid.forEach((fixture, i) => {
     it("should parse fixture " + i, function () {
@@ -51,15 +70,33 @@ describe("Descriptor fixtures", function () {
           descriptorString = removeChecksum(descriptorString);
         }
         const descriptor = Descriptor.fromString(descriptorString, "derivable");
-        assert.strictEqual(
-          Buffer.from(descriptor.atDerivationIndex(fixture.index ?? 0).scriptPubkey()).toString(
-            "hex",
-          ),
-          fixture.script,
+        const scriptPubKey = Buffer.from(
+          descriptor.atDerivationIndex(fixture.index ?? 0).scriptPubkey(),
         );
+        assert.strictEqual(scriptPubKey.toString("hex"), fixture.script);
+        if (descriptor.descType() !== "Bare") {
+          assert.strictEqual(
+            scriptPubKey.length,
+            getScriptPubKeyLength(descriptor.descType()),
+            `Unexpected scriptPubKey length for descriptor ${descriptor.descType()}: ${scriptPubKey.length}`,
+          );
+        }
       }
 
       assert.ok(Number.isInteger(descriptor.maxWeightToSatisfy()));
+
+      switch (descriptor.descType()) {
+        case "Bare":
+        case "Pkh":
+        case "Sh":
+        case "ShWsh":
+        case "Wsh":
+        case "Wpkh":
+        case "ShWpkh":
+          break;
+        default:
+          throw new Error("unexpected descriptor type " + descriptor.descType());
+      }
     });
   });
 });