Scaffolder: Add handlebar 'eq' helper

Signed-off-by: OscarDHdz <v-ohernandez@expediagroup.com>

.changeset/pretty-drinks-serve.md

@@ -0,0 +1,12 @@
+---
+'@backstage/plugin-scaffolder-backend': patch
+---
+
+Scaffolder: Added an 'eq' handlebars helper for use in software template YAML files. This can be used to execute a step depending on the value of an input, e.g.:
+
+```yaml
+steps:
+  id: 'conditional-step'
+  action: 'custom-action'
+  if: '{{ eq parameters.myvalue "custom" }}',
+```

plugins/scaffolder-backend/src/scaffolder/tasks/TaskWorker.test.ts

@@ -203,6 +203,39 @@ describe('TaskWorker', () => {
     expect((event?.body?.output as JsonObject).result).toBe('winning');
   });
 
+  it('should execute steps conditionally with eq helper', async () => {
+    const broker = new StorageTaskBroker(storage, logger);
+    const taskWorker = new TaskWorker({
+      logger,
+      workingDirectory: os.tmpdir(),
+      actionRegistry,
+      taskBroker: broker,
+    });
+
+    const { taskId } = await broker.dispatch({
+      steps: [
+        { id: 'test', name: 'test', action: 'test-action' },
+        {
+          id: 'conditional',
+          name: 'conditional',
+          action: 'test-action',
+          if: '{{ eq steps.test.output.testOutput "winning" }}',
+        },
+      ],
+      output: {
+        result: '{{ steps.conditional.output.testOutput }}',
+      },
+      values: {},
+    });
+
+    const task = await broker.claim();
+    await taskWorker.runOneTask(task);
+
+    const { events } = await storage.listEvents({ taskId });
+    const event = events.find(e => e.type === 'completion');
+    expect((event?.body?.output as JsonObject).result).toBe('winning');
+  });
+
   it('should skip steps conditionally', async () => {
     const broker = new StorageTaskBroker(storage, logger);
     const taskWorker = new TaskWorker({

plugins/scaffolder-backend/src/scaffolder/tasks/TaskWorker.ts

@@ -56,6 +56,8 @@ export class TaskWorker {
     this.handlebars.registerHelper('json', obj => JSON.stringify(obj));
 
     this.handlebars.registerHelper('not', value => !isTruthy(value));
+
+    this.handlebars.registerHelper('eq', (a, b) => a === b);
   }
 
   start() {