fix(s3): move notification destinations into their own module (#2659)

In accordance with new guidelines, we're centralizing cross-service
integrations into their own package. In this case, centralizing S3
Notification Destinations into `@aws-cdk/aws-s3-notifications`.

Fixes #2445.

BREAKING CHANGE: using a Topic, Queue or Lambda as bucket notification
destination now requires an integration object from the
`@aws-cdk/aws-s3-notifications` package.

Author: rix0rrr

packages/@aws-cdk/assert/jest.ts

@@ -1,11 +1,15 @@
 import { Stack } from "@aws-cdk/cdk";
 import { SynthesizedStack } from "@aws-cdk/cx-api";
 import { HaveResourceAssertion, ResourcePart } from "./lib/assertions/have-resource";
+import { MatchStyle, matchTemplate } from "./lib/assertions/match-template";
 import { expect as ourExpect } from './lib/expect';
 
 declare global {
   namespace jest {
     interface Matchers<R> {
+      toMatchTemplate(template: any,
+                      matchStyle?: MatchStyle): R;
+
       toHaveResource(resourceType: string,
                      properties?: any,
                      comparison?: ResourcePart): R;
@@ -18,6 +22,27 @@ declare global {
 }
 
 expect.extend({
+  toMatchTemplate(
+    actual: SynthesizedStack | Stack,
+    template: any,
+    matchStyle?: MatchStyle) {
+
+    const assertion = matchTemplate(template, matchStyle);
+    const inspector = ourExpect(actual);
+    const pass = assertion.assertUsing(inspector);
+    if (pass) {
+      return {
+        pass,
+        message: () => `Not ` + assertion.description
+      };
+    } else {
+      return {
+        pass,
+        message: () => assertion.description
+      };
+    }
+  },
+
   toHaveResource(
       actual: SynthesizedStack | Stack,
       resourceType: string,

packages/@aws-cdk/assert/lib/synth-utils.ts

@@ -14,4 +14,24 @@ export class SynthUtils {
     const synth = new Synthesizer();
     return synth.synthesize(stack, options);
   }
+
+  public static subset(stack: Stack, options: SubsetOptions): any {
+    const template = SynthUtils.toCloudFormation(stack);
+    if (template.Resources) {
+      for (const [key, resource] of Object.entries(template.Resources)) {
+        if (options.resourceTypes && !options.resourceTypes.includes((resource as any).Type)) {
+          delete template.Resources[key];
+        }
+      }
+    }
+
+    return template;
+  }
+}
+
+export interface SubsetOptions {
+  /**
+   * Match all resources of the given type
+   */
+  resourceTypes?: string[];
 }