fix(codepipeline): correctly validate Artifacts used by Actions in th…

packages/@aws-cdk/aws-codepipeline/lib/pipeline.ts

@@ -498,8 +498,8 @@ export class Pipeline extends PipelineBase {
     for (const stage of this.stages) {
       const sortedActions = stage.actions.sort((a1, a2) => a1.runOrder - a2.runOrder);
 
-      // start with inputs
       for (const action of sortedActions) {
+        // start with inputs
         const inputArtifacts = action.inputs;
         for (const inputArtifact of inputArtifacts) {
           if (!inputArtifact.artifactName) {
@@ -508,10 +508,8 @@ export class Pipeline extends PipelineBase {
             ret.push(`Artifact '${inputArtifact.artifactName}' was used as input before being used as output`);
           }
         }
-      }
 
-      // then process outputs by adding them to the Set
-      for (const action of sortedActions) {
+        // then process outputs by adding them to the Set
         const outputArtifacts = action.outputs;
         for (const outputArtifact of outputArtifacts) {
           // output Artifacts always have a name set

packages/@aws-cdk/aws-codepipeline/test/test.artifacts.ts

@@ -1,4 +1,4 @@
-// import { expect, haveResourceLike } from '@aws-cdk/assert';
+import { expect, haveResourceLike } from '@aws-cdk/assert';
 import cdk = require('@aws-cdk/cdk');
 import { Test } from 'nodeunit';
 import codepipeline = require('../lib');
@@ -123,6 +123,55 @@ export = {
 
       test.done();
     },
+
+    "an Action's output can be used as input for an Action in the same Stage with a higher runOrder"(test: Test) {
+      const stack = new cdk.Stack();
+
+      const sourceOutput1 = new codepipeline.Artifact('sourceOutput1');
+      const buildOutput1 = new codepipeline.Artifact('buildOutput1');
+      const sourceOutput2 = new codepipeline.Artifact('sourceOutput2');
+
+      new codepipeline.Pipeline(stack, 'Pipeline', {
+        stages: [
+          {
+            name: 'Source',
+            actions: [
+              new FakeSourceAction({
+                actionName: 'source1',
+                output: sourceOutput1,
+              }),
+              new FakeSourceAction({
+                actionName: 'source2',
+                output: sourceOutput2,
+              }),
+            ],
+          },
+          {
+            name: 'Build',
+            actions: [
+              new FakeBuildAction({
+                actionName: 'build1',
+                input: sourceOutput1,
+                output: buildOutput1,
+              }),
+              new FakeBuildAction({
+                actionName: 'build2',
+                input: sourceOutput2,
+                extraInputs: [buildOutput1],
+                output: new codepipeline.Artifact('buildOutput2'),
+                runOrder: 2,
+              }),
+            ],
+          },
+        ],
+      });
+
+      expect(stack).to(haveResourceLike('AWS::CodePipeline::Pipeline', {
+        //
+      }));
+
+      test.done();
+    },
   },
 };