Correctly recognize whether the cookiecutter command exists

Signed-off-by: Dominik Henneke <dominik.henneke@sda-se.com>

.changeset/weak-needles-peel.md

@@ -0,0 +1,5 @@
+---
+'@backstage/plugin-scaffolder-backend': patch
+---
+
+Correctly recognize whether the cookiecutter command exists

plugins/scaffolder-backend/src/scaffolder/stages/templater/cookiecutter.test.ts

@@ -35,6 +35,7 @@ describe('CookieCutter Templater', () => {
 
   beforeEach(() => {
     jest.clearAllMocks();
+    commandExists.mockRejectedValue(null);
   });
 
   it('should write a cookiecutter.json file with the values from the entity', async () => {
@@ -228,7 +229,7 @@ describe('CookieCutter Templater', () => {
       };
 
       jest.spyOn(fs, 'readdir').mockResolvedValueOnce(['newthing'] as any);
-      commandExists.mockImplementationOnce(() => () => true);
+      commandExists.mockResolvedValueOnce(true);
 
       const templater = new CookieCutter({ containerRunner });
       await templater.run({

plugins/scaffolder-backend/src/scaffolder/stages/templater/cookiecutter.ts

@@ -70,7 +70,10 @@ export class CookieCutter implements TemplaterBase {
       [intermediateDir]: '/output',
     };
 
-    const cookieCutterInstalled = await commandExists('cookiecutter');
+    // the command-exists package returns `true` or throws an error
+    const cookieCutterInstalled = await commandExists('cookiecutter').catch(
+      () => false,
+    );
     if (cookieCutterInstalled) {
       await runCommand({
         command: 'cookiecutter',