fix(core): prevent null outputContent (#1134)

* test(core): demonstrate current behavior of JobExecutorLocal with empty output

This test currently fails.  The next commit fixes it.

* fix(core): prevent null outputContent

in the BakeStatus that JobExecutorLocal.updateStatus returns.

Before this change, if the output of e.g. helm template is an empty string, the BakeStatus object that JobExecutorLocal.updateStatus returns is null, and HelmTemplateUtils.removeTestsDirectoryTemplates throws a NullPointerException.

HelmBakeManifestService.bake calls BakeManifestService.doBake which calls JobExecutorLocal.updateStatus, and then HelmBakeManifestService.bake calls HelmTemplateUtils.removeTestsDirectoryTemplates with the resulting String.

With this change, removeTestsDirectoryTemplates gets an empty string, and so the bake manifest endpoint (e.g. POST /api/v2/manifest/bake/helm) returns an empty Artifact.

Without a corresponding change to clouddriver to handle a null KubernetesManifest, there's still a clouddriver crash in a deploy manifest that consumes the output of this bake, but it's progress.

rosco-core/src/main/groovy/com/netflix/spinnaker/rosco/jobs/local/JobExecutorLocal.groovy

@@ -177,9 +177,7 @@ class JobExecutorLocal implements JobExecutor {
           bakeStatus.state = BakeStatus.State.RUNNING
         }
 
-        if (outputContent) {
-          bakeStatus.outputContent = outputContent
-        }
+        bakeStatus.outputContent = outputContent
 
         if (logsContent) {
           bakeStatus.logsContent = logsContent

rosco-core/src/test/groovy/com/netflix/spinnaker/rosco/jobs/local/JobExecutorLocalSpec.groovy

@@ -79,4 +79,29 @@ Final output
       true                | COMBINED_OUTPUT | COMBINED_OUTPUT
       false               | EXPECTED_OUTPUT | EXPECTED_LOGS
   }
+
+  void 'job executor handles empty output'() {
+      def jobRequest = new JobRequest(
+          tokenizedCommand: ["true"],
+          jobId: SOME_JOB_ID,
+          combineStdOutAndErr: false)
+
+      @Subject
+      def jobExecutorLocal = new JobExecutorLocal(
+          registry: new DefaultRegistry(),
+          timeoutMinutes: 1)
+
+    when:
+      def jobId = jobExecutorLocal.startJob(jobRequest)
+      // Give the script time to run + 100 ms fudge factor
+      sleep(3000)
+      def bakeStatus = jobExecutorLocal.updateJob(jobId)
+
+    then:
+      bakeStatus != null
+      bakeStatus.state == BakeStatus.State.COMPLETED
+      bakeStatus.result == BakeStatus.Result.SUCCESS
+      bakeStatus.outputContent == ""
+      bakeStatus.logsContent == "No output from command."
+  }
 }