fix(rule): make ruleName accessible on Rule object (#4252)

`ruleName` was missing. Add it.

Fixes #3809.

Author: rix0rrr

packages/@aws-cdk/aws-events/lib/rule-ref.ts

@@ -8,4 +8,11 @@ export interface IRule extends IResource {
    * @attribute
    */
   readonly ruleArn: string;
+
+  /**
+   * The name event rule
+   *
+   * @attribute
+   */
+  readonly ruleName: string;
 }

packages/@aws-cdk/aws-events/lib/rule.ts

@@ -78,13 +78,17 @@ export interface RuleProps {
 export class Rule extends Resource implements IRule {
 
   public static fromEventRuleArn(scope: Construct, id: string, eventRuleArn: string): IRule {
+    const parts = Stack.of(scope).parseArn(eventRuleArn);
+
     class Import extends Resource implements IRule {
       public ruleArn = eventRuleArn;
+      public ruleName = parts.resourceName || '';
     }
     return new Import(scope, id);
   }
 
   public readonly ruleArn: string;
+  public readonly ruleName: string;
 
   private readonly targets = new Array<CfnRule.TargetProperty>();
   private readonly eventPattern: EventPattern = { };
@@ -112,6 +116,7 @@ export class Rule extends Resource implements IRule {
       resource: 'rule',
       resourceName: this.physicalName,
     });
+    this.ruleName = this.getResourceNameAttribute(resource.ref);
 
     this.addEventPattern(props.eventPattern);
     this.scheduleExpression = props.schedule && props.schedule.expressionString;

packages/@aws-cdk/aws-events/test/test.rule.ts

@@ -2,7 +2,7 @@ import { expect, haveResource, haveResourceLike } from '@aws-cdk/assert';
 import iam = require('@aws-cdk/aws-iam');
 import { ServicePrincipal } from '@aws-cdk/aws-iam';
 import cdk = require('@aws-cdk/core');
-import { Stack } from '@aws-cdk/core';
+import { CfnResource, Stack } from '@aws-cdk/core';
 import { Test } from 'nodeunit';
 import { EventField, IRule, IRuleTarget, RuleTargetConfig, RuleTargetInput, Schedule } from '../lib';
 import { Rule } from '../lib/rule';
@@ -31,6 +31,26 @@ export = {
     test.done();
   },
 
+  'can get rule name'(test: Test) {
+    const stack = new cdk.Stack();
+    const rule = new Rule(stack, 'MyRule', {
+      schedule: Schedule.rate(cdk.Duration.minutes(10)),
+    });
+
+    new CfnResource(stack, 'Res', {
+      type: 'Test::Resource',
+      properties: {
+        RuleName: rule.ruleName
+      }
+    });
+
+    expect(stack).to(haveResource('Test::Resource', {
+      RuleName: { Ref: 'MyRuleA44AB831' }
+    }));
+
+    test.done();
+  },
+
   'rule with physical name'(test: Test) {
     // GIVEN
     const stack = new cdk.Stack();
@@ -366,10 +386,11 @@ export = {
     const stack = new Stack();
 
     // WHEN
-    const importedRule = Rule.fromEventRuleArn(stack, 'ImportedRule', 'arn:of:rule');
+    const importedRule = Rule.fromEventRuleArn(stack, 'ImportedRule', 'arn:aws:events:us-east-2:123456789012:rule/example');
 
     // THEN
-    test.deepEqual(importedRule.ruleArn, 'arn:of:rule');
+    test.deepEqual(importedRule.ruleArn, 'arn:aws:events:us-east-2:123456789012:rule/example');
+    test.deepEqual(importedRule.ruleName, 'example');
     test.done();
   },