From c6c78b4acbe6c9b0918194dd4b35a9d9bd60d773 Mon Sep 17 00:00:00 2001
From: Heikki Hellgren <heikki.hellgren@op.fi>
Date: Mon, 20 Feb 2023 08:48:06 +0200
Subject: [PATCH] fix: catalog:fetch to throw error for null entity

fixes #16447

Signed-off-by: Heikki Hellgren <heikki.hellgren@op.fi>
---
 .changeset/eight-radios-bake.md               |  5 +++++
 .../actions/builtin/catalog/fetch.test.ts     | 20 ++++++++++++++++++-
 .../actions/builtin/catalog/fetch.ts          |  5 +++++
 3 files changed, 29 insertions(+), 1 deletion(-)
 create mode 100644 .changeset/eight-radios-bake.md

diff --git a/.changeset/eight-radios-bake.md b/.changeset/eight-radios-bake.md
new file mode 100644
index 0000000000..173739a625
--- /dev/null
+++ b/.changeset/eight-radios-bake.md
@@ -0,0 +1,5 @@
+---
+'@backstage/plugin-scaffolder-backend': patch
+---
+
+throw error from catalog:fetch scaffolder action when entity is null and optional is false
diff --git a/plugins/scaffolder-backend/src/scaffolder/actions/builtin/catalog/fetch.test.ts b/plugins/scaffolder-backend/src/scaffolder/actions/builtin/catalog/fetch.test.ts
index f8bdf2bdcb..52c76c8769 100644
--- a/plugins/scaffolder-backend/src/scaffolder/actions/builtin/catalog/fetch.test.ts
+++ b/plugins/scaffolder-backend/src/scaffolder/actions/builtin/catalog/fetch.test.ts
@@ -90,7 +90,7 @@ describe('catalog:fetch', () => {
     expect(mockContext.output).toHaveBeenCalledWith('entity', null);
   });
 
-  it('should throw error if entity not in catalog and optional is false', async () => {
+  it('should throw error if entity fetch fails from catalog and optional is false', async () => {
     getEntityByRef.mockImplementationOnce(() => {
       throw new Error('Not found');
     });
@@ -109,4 +109,22 @@ describe('catalog:fetch', () => {
     });
     expect(mockContext.output).not.toHaveBeenCalled();
   });
+
+  it('should throw error if entity not in catalog and optional is false', async () => {
+    getEntityByRef.mockReturnValueOnce(null);
+
+    await expect(
+      action.handler({
+        ...mockContext,
+        input: {
+          entityRef: 'component:default/test',
+        },
+      }),
+    ).rejects.toThrow('Entity component:default/test not found');
+
+    expect(getEntityByRef).toHaveBeenCalledWith('component:default/test', {
+      token: 'secret',
+    });
+    expect(mockContext.output).not.toHaveBeenCalled();
+  });
 });
diff --git a/plugins/scaffolder-backend/src/scaffolder/actions/builtin/catalog/fetch.ts b/plugins/scaffolder-backend/src/scaffolder/actions/builtin/catalog/fetch.ts
index 913bf32cce..17e510ce64 100644
--- a/plugins/scaffolder-backend/src/scaffolder/actions/builtin/catalog/fetch.ts
+++ b/plugins/scaffolder-backend/src/scaffolder/actions/builtin/catalog/fetch.ts
@@ -93,6 +93,11 @@ export function createFetchCatalogEntityAction(options: {
           throw e;
         }
       }
+
+      if (!entity && !optional) {
+        throw new Error(`Entity ${entityRef} not found`);
+      }
+
       ctx.output('entity', entity ?? null);
     },
   });