Fix codegen for empty parameters

Author: simolus3

lib/src/builder/generator.dart

@@ -82,6 +82,7 @@ class _ContractGeneration {
   final Documentation? documentation;
 
   final List<Spec> _additionalSpecs = [];
+  final Map<FunctionParameter, String> _parameterNames = {};
   final Map<ContractFunction, Reference> _functionToResultClass = {};
 
   // The `self` field, storing a reference to the deployed contract.
@@ -92,6 +93,13 @@ class _ContractGeneration {
 
   _ContractGeneration(this._abi, this._abiCode, this.documentation);
 
+  String _nameOfParameter(FunctionParameter p) {
+    return _parameterNames.putIfAbsent(p, () {
+      if (p.name.isEmpty) return '\$param${_parameterNames.length}';
+      return p.name;
+    });
+  }
+
   Library generate() {
     return Library((b) {
       b.body
@@ -204,15 +212,16 @@ class _ContractGeneration {
     final parameters = <Parameter>[];
     for (final param in function.parameters) {
       parameters.add(Parameter((b) => b
-        ..name = param.name
+        ..name = _nameOfParameter(param)
         ..type = param.type.toDart()));
     }
 
     return parameters;
   }
 
   Code _bodyForImmutable(ContractFunction function) {
-    final params = function.parameters.map((e) => refer(e.name)).toList();
+    final params =
+        function.parameters.map((e) => refer(_nameOfParameter(e))).toList();
 
     final outputs = function.outputs;
     Expression returnValue;

test/builder/data.dart

@@ -1,5 +1,5 @@
 const testCases = <String, String>{
-  '''
+  r'''
 [
     {
       "inputs": [
@@ -35,7 +35,7 @@ const testCases = <String, String>{
       "stateMutability": "pure",
       "type": "function"
     }
-]''': '''
+]''': r'''
 // Generated code, do not modify. Run `build_runner build` to re-generate!
 // @dart=2.12
 import 'package:web3dart/web3dart.dart' as _i1;
@@ -76,7 +76,7 @@ class Retrieve3 {
   final bool var3;
 }
 ''',
-  '''
+  r'''
 [
     {
       "inputs": [],
@@ -127,7 +127,7 @@ class Retrieve3 {
       "stateMutability": "nonpayable",
       "type": "function"
     }
-]''': '''
+]''': r'''
 // Generated code, do not modify. Run `build_runner build` to re-generate!
 // @dart=2.12
 import 'package:web3dart/web3dart.dart' as _i1;
@@ -188,7 +188,56 @@ class GiveMeHello {
   final BigInt num2;
 }
 ''',
-  '''
+  r'''
+[
+    {
+        "inputs": [
+            {
+                "internalType": "address",
+                "name": "",
+                "type": "address"
+            }
+        ],
+        "name": "userTotalAmount",
+        "outputs": [
+            {
+                "internalType": "uint256",
+                "name": "",
+                "type": "uint256"
+            }
+        ],
+        "stateMutability": "view",
+        "type": "function"
+    }   
+]''': r'''
+// Generated code, do not modify. Run `build_runner build` to re-generate!
+// @dart=2.12
+import 'package:web3dart/web3dart.dart' as _i1;
+
+final _contractAbi = _i1.ContractAbi.fromJson(
+    '[{"inputs":[{"internalType":"address","name":"","type":"address"}],"name":"userTotalAmount","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"stateMutability":"view","type":"function"}]',
+    'Contract');
+
+class Contract extends _i1.GeneratedContract {
+  Contract(
+      {required _i1.EthereumAddress address,
+      required _i1.Web3Client client,
+      int? chainId})
+      : super(_i1.DeployedContract(_contractAbi, address), client, chainId);
+
+  /// The optional [atBlock] parameter can be used to view historical data. When
+  /// set, the function will be evaluated in the specified block. By default, the
+  /// latest on-chain block will be used.
+  Future<BigInt> userTotalAmount(_i1.EthereumAddress $param0,
+      {_i1.BlockNum? atBlock}) async {
+    final function = self.function('userTotalAmount');
+    final params = [$param0];
+    final response = await read(function, params, atBlock);
+    return (response[0] as BigInt);
+  }
+}
+''',
+  r'''
 [
     {
         "payable": true,
@@ -199,7 +248,7 @@ class GiveMeHello {
         "stateMutability":"payable",
         "type":"receive"
     }
-]''': '''
+]''': r'''
 // Generated code, do not modify. Run `build_runner build` to re-generate!
 // @dart=2.12
 import 'package:web3dart/web3dart.dart' as _i1;
@@ -216,7 +265,7 @@ class Contract extends _i1.GeneratedContract {
       : super(_i1.DeployedContract(_contractAbi, address), client, chainId);
 }
 ''',
-  '''
+  r'''
 [
     {
         "inputs": [],
@@ -231,7 +280,7 @@ class Contract extends _i1.GeneratedContract {
         "stateMutability": "view",
         "type": "function"
     }
-]''': '''
+]''': r'''
 // Generated code, do not modify. Run `build_runner build` to re-generate!
 // @dart=2.12
 import 'package:web3dart/web3dart.dart' as _i1;
@@ -264,15 +313,15 @@ class Contract extends _i1.GeneratedContract {
   }
 }
 ''',
-  '''
+  r'''
 {
     "abi": [],
     "devdoc": {
         "kind": "dev",
         "methods": {},
         "version": 1
     }
-}''': '''
+}''': r'''
 // Generated code, do not modify. Run `build_runner build` to re-generate!
 // @dart=2.12
 import 'package:web3dart/web3dart.dart' as _i1;

test/builder/mapping.abi.json

@@ -0,0 +1,21 @@
+[
+    {
+        "inputs": [
+            {
+                "internalType": "address",
+                "name": "",
+                "type": "address"
+            }
+        ],
+        "name": "userTotalAmount",
+        "outputs": [
+            {
+                "internalType": "uint256",
+                "name": "",
+                "type": "uint256"
+            }
+        ],
+        "stateMutability": "view",
+        "type": "function"
+    }   
+]

tool/generate_goldens.dart

@@ -34,11 +34,11 @@ Future<void> main() async {
   final resultBuilder = StringBuffer();
   resultBuilder.writeln('const testCases = <String, String>{');
   data.forEach((key, value) {
-    resultBuilder.writeln("'''");
+    resultBuilder.writeln("r'''");
     resultBuilder.write(key);
     resultBuilder.writeln("''':");
 
-    resultBuilder.writeln("'''");
+    resultBuilder.writeln("r'''");
     resultBuilder.write(value);
     resultBuilder.writeln("''',");
   });