Tests: drop notAtLeastDart2_15_0 checks, package requires it.

objectbox_test/test/box_test.dart

@@ -835,7 +835,7 @@ void main() {
     await store.runInTransactionAsync(TxMode.write, callback, simpleItems());
     count = box.count();
     expect(count, equals(6));
-  }, skip: notAtLeastDart2_15_0());
+  });
 
   test('async txn - send and receive relations', () async {
     final testBox = store.box<TestEntity>();
@@ -863,7 +863,7 @@ void main() {
       object.relA.target;
       object.relManyA.length;
     }
-  }, skip: notAtLeastDart2_15_0());
+  });
 
   test('failing transactions', () {
     expect(
@@ -897,7 +897,7 @@ void main() {
             }, simpleItems()),
         throwsA('test-exception'));
     expect(box.count(), equals(0));
-  }, skip: notAtLeastDart2_15_0());
+  });
 
   test('recursive write in write transaction', () {
     store.runInTransaction(TxMode.write, () {
@@ -923,7 +923,7 @@ void main() {
       });
     }, simpleItems());
     expect(box.count(), equals(12));
-  }, skip: notAtLeastDart2_15_0());
+  });
 
   test('recursive read in write transaction', () {
     int count = store.runInTransaction(TxMode.write, () {
@@ -941,7 +941,7 @@ void main() {
       return store.runInTransaction(TxMode.read, box.count);
     }, simpleItems());
     expect(count, equals(6));
-  }, skip: notAtLeastDart2_15_0());
+  });
 
   test('recursive write in read -> fails during creation', () {
     expect(
@@ -965,7 +965,7 @@ void main() {
             }, simpleItems()),
         throwsA(predicate((StateError e) => e.toString().contains(
             'Bad state: failed to create transaction: Cannot start a write transaction inside a read only transaction (OBX_ERROR code 10001)'))));
-  }, skip: notAtLeastDart2_15_0());
+  });
 
   test('failing in recursive txn', () {
     store.runInTransaction(TxMode.write, () {

objectbox_test/test/store_test.dart

@@ -179,7 +179,7 @@ void main() {
       }
     }
     env.closeAndDelete();
-  }, skip: notAtLeastDart2_15_0());
+  });
 
   test('store multi-open', () {
     final stores = <Store>[];
@@ -323,7 +323,7 @@ void main() {
     expect(x, 'foo!');
     expect(env.box.count(), 0); // Must be removed once awaited
     env.closeAndDelete();
-  }, skip: notAtLeastDart2_15_0());
+  });
 
   test('store runAsync returns isolate error', () async {
     final env = TestEnv('store');
@@ -334,7 +334,7 @@ void main() {
       // expected
     }
     env.closeAndDelete();
-  }, skip: notAtLeastDart2_15_0());
+  });
 
   test('store runAsync returns callback error', () async {
     final env = TestEnv('store');
@@ -346,7 +346,7 @@ void main() {
       expect(e, predicate((ArgumentError e) => e.message == 'Return me'));
     }
     env.closeAndDelete();
-  }, skip: notAtLeastDart2_15_0());
+  });
 }
 
 Future<String> _readStringAndRemove(Store store, int id) async {

objectbox_test/test/test_env.dart

@@ -72,17 +72,6 @@ Matcher sameAsList<T>(List<T> list) => unorderedEquals(list);
 Future<void> yieldExecution() async =>
     await Future<void>.delayed(Duration.zero);
 
-dynamic notAtLeastDart2_15_0() {
-  final dartVersion = RegExp('([0-9]+).([0-9]+).([0-9]+)')
-      .firstMatch(Platform.version)
-      ?.group(0);
-  if (dartVersion != null && dartVersion.compareTo('2.15.0') < 0) {
-    return 'Test requires Dart 2.15.0, skipping.';
-  } else {
-    return false;
-  }
-}
-
 bool atLeastDart(String expectedLowestVersion) {
   final dartVersion = RegExp('([0-9]+).([0-9]+).([0-9]+)')
       .firstMatch(Platform.version)