Add simple test.

java/resource-overrides/pom.xml

@@ -85,6 +85,21 @@
             <version>28.1-jre</version>
         </dependency>
 
+        <!-- https://mvnrepository.com/artifact/junit/junit -->
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <version>4.12</version>
+            <scope>test</scope>
+        </dependency>
+        <!-- https://mvnrepository.com/artifact/org.skyscreamer/jsonassert -->
+        <dependency>
+            <groupId>org.skyscreamer</groupId>
+            <artifactId>jsonassert</artifactId>
+            <version>1.5.0</version>
+            <scope>test</scope>
+        </dependency>
+
     </dependencies>
 
 

java/resource-overrides/src/main/java/software/amazon/awscdk/examples/ResourceOverridesStack.java

@@ -114,6 +114,7 @@ public ResourceOverridesStack(final Construct parent, final String name) {
         // The default child resource is called `Resource`, but secondary resources, such as
         // an LaunchConfig, InstanceRole will have a different ID.
         // See https://docs.aws.amazon.com/cdk/api/latest/docs/@aws-cdk_core.ConstructNode.html#defaultchild
+        // You can see all the resources under given construct by running `cdk synth` and looking for `aws:cdk:path`
         //
         CfnLaunchConfiguration launchConfiguration = (CfnLaunchConfiguration) asg.getNode().findChild("LaunchConfig");
         launchConfiguration.addPropertyOverride("Foo.Bar", "Hello");

java/resource-overrides/src/test/java/software/amazon/awscdk/examples/ResourceOverridesStackTest.java

@@ -0,0 +1,45 @@
+package software.amazon.awscdk.examples;
+
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import org.junit.Test;
+import org.skyscreamer.jsonassert.JSONAssert;
+import org.skyscreamer.jsonassert.JSONCompareMode;
+import software.amazon.awscdk.core.App;
+import software.amazon.awscdk.core.ConstructNode;
+import software.amazon.awscdk.core.IConstruct;
+import software.amazon.awscdk.core.Stack;
+import software.amazon.awscdk.cxapi.CloudFormationStackArtifact;
+
+import java.io.IOException;
+
+public class ResourceOverridesStackTest {
+    private static final ObjectMapper JSON = new ObjectMapper();
+
+    @Test
+    public void shouldGenerateValidCloudFormationTemplate() throws Exception {
+        App app = new App();
+        Stack stack = new ResourceOverridesStack(app, "resource-overrides");
+
+        String actual = getStackTemplateJson(stack)
+                .toPrettyString();
+        String expected = readJsonFromResource("testResourceOverrides.expected.json")
+                .toPrettyString();
+
+        JSONAssert.assertEquals(expected, actual, JSONCompareMode.LENIENT);
+    }
+
+    private static JsonNode readJsonFromResource(String resourceName) throws IOException {
+        return JSON.readTree(
+                ResourceOverridesStackTest.class.getResource(resourceName)
+        );
+    }
+
+    private static JsonNode getStackTemplateJson(Stack stack) {
+        IConstruct root = stack.getNode().getRoot();
+        CloudFormationStackArtifact stackArtifact = ConstructNode.synth(root.getNode())
+                .getStackByName(stack.getStackName());
+
+        return JSON.valueToTree(stackArtifact.getTemplate());
+    }
+}