test(share_plus): Integration test (#1033)

* test(share_plus): test isNotNull

* style(share_plus): Delete unused imported package

* style(share_plus): Flutter format .

* style(share_plus): Describe more precisely

* test(share_plus): Improve the readability of share_plus test file's names

* style: rename

Author: Chever-John

packages/share_plus/share_plus/example/integration_test/share_plus_test.dart

@@ -14,4 +14,8 @@ void main() {
   testWidgets('Can launch share', (WidgetTester tester) async {
     expect(Share.share('message', subject: 'title'), completes);
   });
+
+  testWidgets('Can launch shareWithResult', (WidgetTester tester) async {
+    expect(Share.shareWithResult('message', subject: 'title'), isNotNull);
+  });
 }