add test to validate it

metadata/src/utils/validation.rs

@@ -268,7 +268,6 @@ fn get_extrinsic_hash(
             &get_type_hash(registry, signed_extension.additional_ty, &mut cache),
         )
     }
-
     bytes
 }
 
@@ -522,7 +521,10 @@ pub fn get_pallet_hash(
     let registry = pallet.types;
 
     let call_bytes = match pallet.call_ty_id() {
-        Some(calls) => get_type_hash(registry, calls, &mut cache),
+        Some(calls) => {
+            get_type_hash(registry, calls, &mut cache)
+
+        },
         None => [0u8; HASH_LEN],
     };
     let event_bytes = match pallet.event_ty_id() {
@@ -666,7 +668,6 @@ impl<'a> MetadataHasher<'a> {
             .include_custom_values
             .then(|| get_custom_metadata_hash(&metadata.custom(), Some(&mut cache)))
             .unwrap_or_default();
-
         concat_and_hash6(
             &pallet_hash,
             &apis_hash,
@@ -682,7 +683,10 @@ impl<'a> MetadataHasher<'a> {
 mod tests {
     use super::*;
     use bitvec::{order::Lsb0, vec::BitVec};
-    use frame_metadata::v15;
+    use frame_metadata::v15::{
+        self, PalletEventMetadata, PalletStorageMetadata, StorageEntryMetadata,
+        StorageEntryModifier,
+    };
     use scale_info::{meta_type, Registry};
 
     // Define recursive types.
@@ -1136,4 +1140,141 @@ mod tests {
             to_hash(meta_type::<StructE2>())
         );
     }
+
+    fn metadata_with_pallet_events() -> Metadata {
+        #[allow(dead_code)]
+        #[derive(scale_info::TypeInfo)]
+        struct FirstEvent {
+            s: String,
+        }
+
+        #[allow(dead_code)]
+        #[derive(scale_info::TypeInfo)]
+        struct SecondEvent {
+            n: u8,
+        }
+
+        #[allow(dead_code)]
+        #[derive(scale_info::TypeInfo)]
+        enum Events {
+            First(FirstEvent),
+            Second(SecondEvent),
+        }
+
+        #[allow(dead_code)]
+        #[derive(scale_info::TypeInfo)]
+        enum Errors {
+            First(DispatchError),
+            Second(DispatchError),
+        }
+
+        #[allow(dead_code)]
+        #[derive(scale_info::TypeInfo)]
+        enum Calls {
+            First(u8),
+            Second(u8),
+        }
+
+        #[allow(dead_code)]
+        enum DispatchError {
+            A,
+            B,
+            C,
+        }
+
+        impl scale_info::TypeInfo for DispatchError {
+            type Identity = DispatchError;
+
+            fn type_info() -> scale_info::Type {
+                scale_info::Type {
+                    path: scale_info::Path {
+                        segments: vec!["sp_runtime", "DispatchError"],
+                    },
+                    type_params: vec![],
+                    type_def: TypeDef::Variant(TypeDefVariant { variants: vec![] }),
+                    docs: vec![],
+                }
+            }
+        }
+
+        let pallets = vec![
+            v15::PalletMetadata {
+                name: "First",
+                index: 0,
+                calls: Some(v15::PalletCallMetadata {
+                    ty: meta_type::<u8>(),
+                }),
+                storage: Some(PalletStorageMetadata {
+                    prefix: "___",
+                    entries: vec![StorageEntryMetadata {
+                        name: "Hello",
+                        modifier: StorageEntryModifier::Optional,
+                        // Note: This is the important part here:
+                        // The Events type will be trimmed down and this trimming needs to be reflected
+                        // when the hash of this storage item is computed.
+                        ty: frame_metadata::v14::StorageEntryType::Plain(meta_type::<Vec<Events>>()),
+                        default: vec![],
+                        docs: vec![],
+                    }],
+                }),
+                event: Some(PalletEventMetadata {
+                    ty: meta_type::<FirstEvent>(),
+                }),
+                constants: vec![],
+                error: None,
+                docs: vec![],
+            },
+            v15::PalletMetadata {
+                name: "Second",
+                index: 1,
+                calls: Some(v15::PalletCallMetadata {
+                    ty: meta_type::<u64>(),
+                }),
+                storage: None,
+                event: Some(PalletEventMetadata {
+                    ty: meta_type::<SecondEvent>(),
+                }),
+                constants: vec![],
+                error: None,
+                docs: vec![],
+            },
+        ];
+
+        v15::RuntimeMetadataV15::new(
+            pallets,
+            build_default_extrinsic(),
+            meta_type::<()>(),
+            vec![],
+            v15::OuterEnums {
+                call_enum_ty: meta_type::<Calls>(),
+                event_enum_ty: meta_type::<Events>(),
+                error_enum_ty: meta_type::<Errors>(),
+            },
+            v15::CustomMetadata {
+                map: Default::default(),
+            },
+        )
+        .try_into()
+        .expect("can build valid metadata")
+    }
+
+    #[test]
+    fn hash_comparison_trimmed_metadata() {
+        // trim the metadata:
+        let metadata = metadata_with_pallet_events();
+        let trimmed_metadata = {
+            let mut m = metadata.clone();
+            m.retain(|e| e == "First", |_| true);
+            m
+        };
+
+        // test that the hashes are the same:
+        let hash = MetadataHasher::new(&metadata)
+            .only_these_pallets(&["First"])
+            .hash();
+        let hash_trimmed = MetadataHasher::new(&trimmed_metadata)
+            .hash();
+
+        assert_eq!(hash, hash_trimmed);
+    }
 }