test: contract json roundtrip

packages/types/lib/src/contract.dart

@@ -2,6 +2,7 @@ import 'package:collection/collection.dart';
 import 'package:meta/meta.dart';
 import 'package:openapi/api.dart' as openapi;
 import 'package:types/api.dart';
+import 'package:types/types.dart';
 
 /// A contract to deliver goods to a faction.
 class Contract {
@@ -79,11 +80,15 @@ class Contract {
 
   /// Converts the Contract to JSON.
   Map<String, dynamic> toJson() {
+    // Work around OpenAPI not supporting toJson recursion.
+    final termsJson = terms.toJson();
+    termsJson['payment'] = (termsJson['payment'] as ContractPayment).toJson();
+
     return <String, dynamic>{
       'id': id,
       'factionSymbol': factionSymbol,
       'type': type.value,
-      'terms': terms.toJson(),
+      'terms': termsJson,
       'deadlineToAccept': deadlineToAccept.toIso8601String(),
       'accepted': accepted,
       'fulfilled': fulfilled,

packages/types/test/src/contract_test.dart

@@ -41,4 +41,18 @@ void main() {
     expect(fulfill.contractAction, ContractAction.fulfillment);
     expect(fulfill.creditsChange, 20);
   });
+
+  test('Contract json round trip', () {
+    final now = DateTime(2021);
+    final contractTerms = ContractTerms(
+      deadline: now,
+      payment: ContractPayment(onAccepted: 10, onFulfilled: 20),
+    );
+    final contract = Contract.test(id: 'id', terms: contractTerms);
+
+    final json = contract.toJson();
+    final fromJson = Contract.fromJson(json);
+    // Contract does not currently support equality so compare the json.
+    expect(fromJson.toJson(), contract.toJson());
+  });
 }