fix(codepipeline): manual approval action doesn't have configuration without a topic

packages/@aws-cdk/aws-codepipeline-actions/lib/manual-approval-action.ts

@@ -76,13 +76,15 @@ export class ManualApprovalAction extends Action {
     }
 
     return {
-      configuration: this._notificationTopic
-        ? {
-          NotificationArn: this._notificationTopic.topicArn,
-          CustomData: this.props.additionalInformation,
-          ExternalEntityLink: this.props.externalEntityLink,
-        }
-        : undefined,
+      configuration: undefinedIfAllValuesAreEmpty({
+        NotificationArn: this._notificationTopic?.topicArn,
+        CustomData: this.props.additionalInformation,
+        ExternalEntityLink: this.props.externalEntityLink,
+      }),
     };
   }
 }
+
+function undefinedIfAllValuesAreEmpty(object: object): object | undefined {
+  return Object.values(object).some(v => v !== undefined) ? object : undefined;
+}

packages/@aws-cdk/aws-codepipeline-actions/test/test.manual-approval.ts

@@ -0,0 +1,78 @@
+import { expect, haveResourceLike} from '@aws-cdk/assert';
+import * as codepipeline from '@aws-cdk/aws-codepipeline';
+import * as sns from '@aws-cdk/aws-sns';
+import { SecretValue, Stack } from '@aws-cdk/core';
+import { Test } from 'nodeunit';
+import * as cpactions from '../lib';
+
+// tslint:disable:object-literal-key-quotes
+
+export = {
+  'manual approval Action': {
+    'allows passing an SNS Topic when constructing it'(test: Test) {
+      const stack = new Stack();
+      const topic = new sns.Topic(stack, 'Topic');
+      const manualApprovalAction = new cpactions.ManualApprovalAction({
+        actionName: 'Approve',
+        notificationTopic: topic,
+      });
+      const pipeline = new codepipeline.Pipeline(stack, 'pipeline');
+      const stage = pipeline.addStage({ stageName: 'stage' });
+      stage.addAction(manualApprovalAction);
+
+      test.equal(manualApprovalAction.notificationTopic, topic);
+
+      test.done();
+    },
+
+    'renders CustomData and ExternalEntityLink even if notificationTopic was not passed'(test: Test) {
+      const stack = new Stack();
+      new codepipeline.Pipeline(stack, 'pipeline', {
+        stages: [
+          {
+            stageName: 'Source',
+            actions: [new cpactions.GitHubSourceAction({
+              actionName: 'Source',
+              output: new codepipeline.Artifact(),
+              oauthToken: SecretValue.plainText('secret'),
+              owner: 'aws',
+              repo: 'aws-cdk',
+            })],
+          },
+          {
+            stageName: 'Approve',
+            actions: [
+              new cpactions.ManualApprovalAction({
+                actionName: 'Approval',
+                additionalInformation: 'extra info',
+                externalEntityLink: 'external link',
+              }),
+            ],
+          },
+        ],
+      });
+
+      expect(stack).to(haveResourceLike('AWS::CodePipeline::Pipeline', {
+        "Stages": [
+          {
+            "Name": "Source",
+          },
+          {
+            "Name": "Approve",
+            "Actions": [
+              {
+                "Name": "Approval",
+                "Configuration": {
+                  "CustomData": "extra info",
+                  "ExternalEntityLink": "external link",
+                },
+              },
+            ],
+          },
+        ],
+      }));
+
+      test.done();
+    },
+  },
+};

packages/@aws-cdk/aws-codepipeline-actions/test/test.pipeline.ts

@@ -371,22 +371,6 @@ export = {
     test.done();
   },
 
-  'manual approval Action': {
-    'allows passing an SNS Topic when constructing it'(test: Test) {
-      const stack = new Stack();
-      const topic = new sns.Topic(stack, 'Topic');
-      const manualApprovalAction = new cpactions.ManualApprovalAction({
-        actionName: 'Approve',
-        notificationTopic: topic,
-      });
-      stageForTesting(stack).addAction(manualApprovalAction);
-
-      test.equal(manualApprovalAction.notificationTopic, topic);
-
-      test.done();
-    },
-  },
-
   'PipelineProject': {
     'with a custom Project Name': {
       'sets the source and artifacts to CodePipeline'(test: Test) {
@@ -977,8 +961,3 @@ export = {
     },
   },
 };
-
-function stageForTesting(stack: Stack): codepipeline.IStage {
-  const pipeline = new codepipeline.Pipeline(stack, 'pipeline');
-  return pipeline.addStage({ stageName: 'stage' });
-}