feat(nns): Use hard coded DID file for uninstall_code NNS Function

rs/nns/governance/src/proposals/execute_nns_function.rs

@@ -17,6 +17,17 @@ use ic_nns_constants::{
 };
 use std::sync::Arc;
 
+/// A partial Candid interface for the management canister (ic_00) that contains the necessary
+/// methods for all the ExecuteNnsFunction proposals. Currently, only the uninstall_code method is
+/// supported.
+const PARTIAL_IC_00_CANDID: &str = r#"type uninstall_code_args = record {
+    canister_id : principal;
+    sender_canister_version : opt nat64;
+};
+service ic : {
+    uninstall_code : (uninstall_code_args) -> ();
+}"#;
+
 #[derive(Debug, Clone, PartialEq)]
 pub struct ValidExecuteNnsFunction {
     pub nns_function: ValidNnsFunction,
@@ -72,6 +83,13 @@ impl ValidExecuteNnsFunction {
 
     async fn get_candid_source(&self, env: Arc<dyn Environment>) -> Result<String, String> {
         let (canister_id, _method_name) = self.nns_function.canister_and_function();
+
+        // The management canister (ic_00) doesn't expose candid:service metadata, so we return a
+        // hard-coded DID file for it.
+        if canister_id == CanisterId::ic_00() {
+            return Ok(PARTIAL_IC_00_CANDID.to_string());
+        }
+
         let request = CanisterMetadataRequest::new(canister_id, "candid:service".to_string());
         let encoded_request = Encode!(&request).expect("Failed to encode payload");
         let response = env

rs/nns/governance/src/proposals/execute_nns_function_tests.rs

@@ -6,7 +6,7 @@ use crate::{
     },
     test_utils::{ExpectedCallCanisterMethodCallArguments, MockEnvironment},
 };
-use candid::Encode;
+use candid::{Encode, Nat};
 use ic_base_types::CanisterId;
 use ic_management_canister_types_private::{CanisterMetadataRequest, CanisterMetadataResponse};
 use ic_nns_constants::CYCLES_MINTING_CANISTER_ID;
@@ -186,3 +186,47 @@ service : {
         })
     );
 }
+
+#[tokio::test]
+async fn test_to_self_describing_uninstall_code() {
+    // Create the uninstall_code_args payload
+    #[derive(candid::CandidType)]
+    struct UninstallCodeArgs {
+        canister_id: CanisterId,
+        sender_canister_version: Option<u64>,
+    }
+
+    let target_canister = CanisterId::from_u64(123);
+    let arg = UninstallCodeArgs {
+        canister_id: target_canister,
+        sender_canister_version: Some(42),
+    };
+    let payload = Encode!(&arg).unwrap();
+
+    let execute_nns_function = ValidExecuteNnsFunction {
+        nns_function: ValidNnsFunction::UninstallCode,
+        payload,
+    };
+
+    // No canister_metadata call expected a hard-coded DID file is used instead.
+    let env = Arc::new(MockEnvironment::new(vec![], 0));
+
+    let proposal_action = ValidProposalAction::ExecuteNnsFunction(execute_nns_function);
+    let result = proposal_action.to_self_describing(env).await.unwrap();
+
+    assert_eq!(result.type_name, "Uninstall Code");
+    assert!(
+        result
+            .type_description
+            .contains("Uninstall code of a canister")
+    );
+    assert_eq!(
+        SelfDescribingValue::from(result.value.unwrap()),
+        SelfDescribingValue::Map(hashmap! {
+            "canister_id".to_string() => SelfDescribingValue::Text("2uzo4-eaaaa-aaaaa-aab5q-cai".to_string()),
+            "sender_canister_version".to_string() => SelfDescribingValue::Array(vec![
+                SelfDescribingValue::Nat(Nat::from(42u64)),
+            ]),
+        })
+    );
+}