CORDA-2715 - Update test runner instructions for CorDapp tutorial (#4863)

* made consistent with template review

* fixing nested bullet layouts

* updating based on (awesome) comments

* next iteration :-)

* more fixes

docs/source/tutorial-cordapp.rst

@@ -481,6 +481,45 @@ Integration tests
 ~~~~~~~~~~~~~~~~~
 You can run the CorDapp's integration tests by running the ``Run Integration Tests - Kotlin`` run configuration.
 
+Running tests in IntelliJ
+~~~~~~~~~~~~~~~~~~~~~~~~~
+
+We recommend editing your IntelliJ preferences so that you use the Gradle runner - this means that the quasar utils
+plugin will make sure that some flags (like ``-javaagent`` - see :ref:`below <tutorial_cordapp_alternative_test_runners>`) are
+set for you.
+
+To switch to using the Gradle runner:
+
+* Navigate to ``Build, Execution, Deployment -> Build Tools -> Gradle -> Runner`` (or search for `runner`)
+
+  * Windows: this is in "Settings"
+  * MacOS: this is in "Preferences"
+
+* Set "Delegate IDE build/run actions to gradle" to true
+* Set "Run test using:" to "Gradle Test Runner"
+
+.. _tutorial_cordapp_alternative_test_runners:
+
+If you would prefer to use the built in IntelliJ JUnit test runner, you can add some code to your ``build.gradle`` file and
+it will copy your quasar JAR file to the lib directory. You will also need to specify ``-javaagent:lib/quasar.jar``
+and set the run directory to the project root directory for each test.
+
+Add the following to your ``build.gradle`` file - ideally to a ``build.gradle`` that already contains the quasar-utils plugin line:
+
+.. sourcecode:: groovy
+
+    apply plugin: 'net.corda.plugins.quasar-utils'
+
+    task installQuasar(type: Copy) {
+        destinationDir rootProject.file("lib")
+        from(configurations.quasar) {
+            rename 'quasar-core(.*).jar', 'quasar.jar'
+        }
+    }
+
+
+and then you can run ``gradlew installQuasar``.
+
 Debugging your CorDapp
 ----------------------