doc: integration testing

doc/dev_guide/integration_testing.md

@@ -0,0 +1,15 @@
+# Integration Testing
+
+## Running Integration tests
+
+Integration tests can be run by calling the runner file with specific platform
+
+```shell
+flutter test .\integration_test\runner.dart -d <platform>
+```
+
+Example:
+
+```shell
+flutter test .\integration_test\runner.dart -d windows
+```