Contracts: Translate .wat fixtures to rust (#2654)

- Translate all pallet-contracts fixtures from `wat` to Rust files.
- Fix read_sandbox_memory_as to not use MaxEncodedLen as this could
break if used with types with a non-fixed encoded len.

---------

Co-authored-by: alvicsam <alvicsam@gmail.com>
Co-authored-by: Alexander Samusev <41779041+alvicsam@users.noreply.github.com>
Co-authored-by: Alexander Theißen <alex.theissen@me.com>
Co-authored-by: command-bot <>

substrate/frame/contracts/src/tests.rs

@@ -178,7 +178,7 @@ parameter_types! {
 pub struct TestExtension {
 	enabled: bool,
 	last_seen_buffer: Vec<u8>,
-	last_seen_inputs: (u32, u32, u32, u32),
+	last_seen_input_len: u32,
 }
 
 #[derive(Default)]
@@ -201,14 +201,14 @@ impl TestExtension {
 		TestExtensionTestValue::get().last_seen_buffer.clone()
 	}
 
-	fn last_seen_inputs() -> (u32, u32, u32, u32) {
-		TestExtensionTestValue::get().last_seen_inputs
+	fn last_seen_input_len() -> u32 {
+		TestExtensionTestValue::get().last_seen_input_len
 	}
 }
 
 impl Default for TestExtension {
 	fn default() -> Self {
-		Self { enabled: true, last_seen_buffer: vec![], last_seen_inputs: (0, 0, 0, 0) }
+		Self { enabled: true, last_seen_buffer: vec![], last_seen_input_len: 0 }
 	}
 }
 
@@ -231,9 +231,7 @@ impl ChainExtension<Test> for TestExtension {
 			},
 			1 => {
 				let env = env.only_in();
-				TestExtensionTestValue::mutate(|e| {
-					e.last_seen_inputs = (env.val0(), env.val1(), env.val2(), env.val3())
-				});
+				TestExtensionTestValue::mutate(|e| e.last_seen_input_len = env.val1());
 				Ok(RetVal::Converging(id))
 			},
 			2 => {
@@ -2154,8 +2152,7 @@ fn chain_extension_works() {
 		)
 		.result
 		.unwrap();
-		// those values passed in the fixture
-		assert_eq!(TestExtension::last_seen_inputs(), (4, 4, 16, 12));
+		assert_eq!(TestExtension::last_seen_input_len(), 4);
 
 		// 2 = charge some extra weight (amount supplied in the fifth byte)
 		let result = Contracts::bare_call(
@@ -3511,7 +3508,7 @@ fn failed_deposit_charge_should_roll_back_call() {
 	let result = execute().unwrap();
 
 	// Bump the deposit per byte to a high value to trigger a FundsUnavailable error.
-	DEPOSIT_PER_BYTE.with(|c| *c.borrow_mut() = ED);
+	DEPOSIT_PER_BYTE.with(|c| *c.borrow_mut() = 20);
 	assert_err_with_weight!(execute(), TokenError::FundsUnavailable, result.actual_weight);
 }
 

substrate/frame/contracts/src/wasm/mod.rs

@@ -2460,7 +2460,7 @@ mod tests {
 		assert_eq!(
 			result,
 			Err(ExecError {
-				error: Error::<Test>::OutOfBounds.into(),
+				error: Error::<Test>::DecodingFailed.into(),
 				origin: ErrorOrigin::Caller,
 			})
 		);
@@ -3428,4 +3428,20 @@ mod tests {
 		assert_eq!(delegate_dependencies.len(), 1);
 		assert_eq!(delegate_dependencies[0].as_bytes(), [1; 32]);
 	}
+
+	// This test checks that [`Runtime::read_sandbox_memory_as`] works, when the decoded type has a
+	// max_len greater than the memory size, but the decoded data fits into the memory.
+	#[test]
+	fn read_sandbox_memory_as_works_with_max_len_out_of_bounds_but_fitting_actual_data() {
+		use frame_support::BoundedVec;
+		use sp_core::ConstU32;
+
+		let mut ext = MockExt::default();
+		let runtime = Runtime::new(&mut ext, vec![]);
+		let data = vec![1u8, 2, 3];
+		let memory = data.encode();
+		let decoded: BoundedVec<u8, ConstU32<128>> =
+			runtime.read_sandbox_memory_as(&memory, 0u32).unwrap();
+		assert_eq!(decoded.into_inner(), data);
+	}
 }

substrate/frame/contracts/src/wasm/runtime.rs

@@ -583,9 +583,8 @@ impl<'a, E: Ext + 'a> Runtime<'a, E> {
 		ptr: u32,
 	) -> Result<D, DispatchError> {
 		let ptr = ptr as usize;
-		let mut bound_checked = memory
-			.get(ptr..ptr + D::max_encoded_len() as usize)
-			.ok_or_else(|| Error::<E::T>::OutOfBounds)?;
+		let mut bound_checked = memory.get(ptr..).ok_or_else(|| Error::<E::T>::OutOfBounds)?;
+
 		let decoded = D::decode_with_depth_limit(MAX_DECODE_NESTING, &mut bound_checked)
 			.map_err(|_| DispatchError::from(Error::<E::T>::DecodingFailed))?;
 		Ok(decoded)