update integration test instructions

README.md

@@ -52,7 +52,15 @@ go test ./path/to/package
 
 ### Integration Tests
 
-Integration tests use a custom bash testing framework that interacts with a running instance of the chain. To run all integration tests:
+Integration tests use a custom bash testing framework that interacts with a running instance of the chain. 
+
+Before running any tests, make sure that the dev chain is running:
+
+```
+ignite chain serve
+```
+
+To run all integration tests:
 
 ```
 make test