test: track node sizes (#497)

Author: DaniPopes

CONTRIBUTING.md

@@ -184,11 +184,25 @@ include one or more tests to ensure that Solar does not regress in the future.
 There are a few ways to write tests:
 - [unit tests][unit-tests]
 - [documentation tests][documentation-tests]
+- [snapshot tests][snapshot-tests]
 - [integration tests][integration-tests]
 
-Unit and documentation tests are used to test individual library functions or modules, whereas
+Unit, documentation, and snapshot tests are used to test individual library functions or modules, whereas
 integration tests are used to test the compiler binary.
 
+#### Snapshot Tests
+
+Snapshot tests are a subset of unit tests that capture some specific output and compare it to a snapshot, usually defined inline in the test itself.
+
+We use `snapbox` as the snapshot testing framework, which does not require any external binaries to be installed.
+
+You can automatically create or update the snapshots by running tests normally with the `SNAPSHOTS=overwrite` environment variable,
+optionally specifying the crate or test name, as you would with `cargo test` normally.
+For example:
+```bash
+SNAPSHOTS=overwrite cargo test -p solar-ast
+```
+
 #### Integration Tests
 
 Integration tests are located in the `tests` directory. They are run using the

Cargo.lock

@@ -35,5 +35,8 @@ semver.workspace = true
 num-rational.workspace = true
 strum.workspace = true
 
+[dev-dependencies]
+snapbox.workspace = true
+
 [features]
 nightly = ["solar-data-structures/nightly", "solar-interface/nightly"]

crates/ast/Cargo.toml

@@ -185,4 +185,61 @@ mod tests {
         assert_no_drop::<Item<'_>>();
         assert_no_drop::<SourceUnit<'_>>();
     }
+
+    // Ensure that we track the size of individual AST nodes.
+    #[test]
+    #[cfg_attr(not(target_pointer_width = "64"), ignore = "64-bit only")]
+    #[cfg_attr(feature = "nightly", ignore = "stable only")]
+    fn sizes() {
+        use snapbox::{assert_data_eq, str};
+        #[track_caller]
+        fn assert_size<T>(size: impl snapbox::IntoData) {
+            assert_size_(std::mem::size_of::<T>(), size.into_data());
+        }
+        #[track_caller]
+        fn assert_size_(actual: usize, expected: snapbox::Data) {
+            assert_data_eq!(actual.to_string(), expected);
+        }
+
+        assert_size::<Span>(str!["8"]);
+        assert_size::<DocComments<'_>>(str!["16"]);
+
+        assert_size::<SourceUnit<'_>>(str!["16"]);
+
+        assert_size::<PragmaDirective<'_>>(str!["40"]);
+        assert_size::<ImportDirective<'_>>(str!["40"]);
+        assert_size::<UsingDirective<'_>>(str!["64"]);
+        assert_size::<ItemContract<'_>>(str!["64"]);
+        assert_size::<ItemFunction<'_>>(str!["184"]);
+        assert_size::<VariableDefinition<'_>>(str!["88"]);
+        assert_size::<ItemStruct<'_>>(str!["32"]);
+        assert_size::<ItemEnum<'_>>(str!["32"]);
+        assert_size::<ItemUdvt<'_>>(str!["48"]);
+        assert_size::<ItemError<'_>>(str!["40"]);
+        assert_size::<ItemEvent<'_>>(str!["40"]);
+        assert_size::<ItemKind<'_>>(str!["184"]);
+        assert_size::<Item<'_>>(str!["208"]);
+
+        assert_size::<FunctionHeader<'_>>(str!["144"]);
+        assert_size::<ParameterList<'_>>(str!["24"]);
+
+        assert_size::<ElementaryType>(str!["3"]);
+        assert_size::<TypeKind<'_>>(str!["24"]);
+        assert_size::<Type<'_>>(str!["32"]);
+
+        assert_size::<ExprKind<'_>>(str!["40"]);
+        assert_size::<Expr<'_>>(str!["48"]);
+
+        assert_size::<StmtKind<'_>>(str!["64"]);
+        assert_size::<Stmt<'_>>(str!["88"]);
+        assert_size::<Block<'_>>(str!["24"]);
+
+        assert_size::<yul::ExprCall<'_>>(str!["32"]);
+        assert_size::<yul::ExprKind<'_>>(str!["40"]);
+        assert_size::<yul::Expr<'_>>(str!["48"]);
+
+        assert_size::<yul::StmtKind<'_>>(str!["120"]);
+        assert_size::<yul::Stmt<'_>>(str!["144"]);
+        assert_size::<yul::Block<'_>>(str!["24"]);
+    }
 }

crates/ast/src/ast/mod.rs

@@ -39,6 +39,9 @@ alloy-json-abi.workspace = true
 serde.workspace = true
 serde_json.workspace = true
 
+[dev-dependencies]
+snapbox.workspace = true
+
 [features]
 nightly = [
     "solar-ast/nightly",

crates/sema/Cargo.toml

@@ -1472,3 +1472,46 @@ pub struct TypeMapping<'hir> {
     pub value: Type<'hir>,
     pub value_name: Option<Ident>,
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    // Ensure that we track the size of individual HIR nodes.
+    #[test]
+    #[cfg_attr(not(target_pointer_width = "64"), ignore = "64-bit only")]
+    #[cfg_attr(feature = "nightly", ignore = "stable only")]
+    fn sizes() {
+        use snapbox::{assert_data_eq, str};
+        #[track_caller]
+        fn assert_size<T>(size: impl snapbox::IntoData) {
+            assert_size_(std::mem::size_of::<T>(), size.into_data());
+        }
+        #[track_caller]
+        fn assert_size_(actual: usize, expected: snapbox::Data) {
+            assert_data_eq!(actual.to_string(), expected);
+        }
+
+        assert_size::<Hir<'_>>(str!["216"]);
+
+        assert_size::<Item<'_, '_>>(str!["16"]);
+        assert_size::<Contract<'_>>(str!["120"]);
+        assert_size::<Function<'_>>(str!["136"]);
+        assert_size::<Struct<'_>>(str!["48"]);
+        assert_size::<Enum<'_>>(str!["48"]);
+        assert_size::<Udvt<'_>>(str!["56"]);
+        assert_size::<Error<'_>>(str!["48"]);
+        assert_size::<Event<'_>>(str!["48"]);
+        assert_size::<Variable<'_>>(str!["96"]);
+
+        assert_size::<TypeKind<'_>>(str!["16"]);
+        assert_size::<Type<'_>>(str!["24"]);
+
+        assert_size::<ExprKind<'_>>(str!["56"]);
+        assert_size::<Expr<'_>>(str!["72"]);
+
+        assert_size::<StmtKind<'_>>(str!["32"]);
+        assert_size::<Stmt<'_>>(str!["40"]);
+        assert_size::<Block<'_>>(str!["24"]);
+    }
+}