feat: add descType method to WrapDescriptor

Issue: BTC-1451

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

@@ -60,6 +60,19 @@ describe("Descriptor fixtures", function () {
       }
 
       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());
+      }
     });
   });
 });