throw if we are passed the empty string - we know this won't work

Signed-off-by: David Roberts <David.Roberts@orbis.com>

plugins/azure-devops-backend/src/service/router.test.ts

@@ -572,6 +572,14 @@ describe('createRouter', () => {
       expect(response.status).toEqual(400);
     });
   });
+
+  describe('GET /readme/:projectName/:repoName with a bad readme path (empty string)', () => {
+    it('throws InputError', async () => {
+      const response = await request(app).get('/readme/myProject/myRepo?path=');
+      expect(azureDevOpsApi.getReadme).not.toHaveBeenCalled();
+      expect(response.status).toEqual(400);
+    });
+  });
 });
 
 function getReadmeMock() {

plugins/azure-devops-backend/src/service/router.ts

@@ -228,6 +228,10 @@ export async function createRouter(
       throw new InputError('Invalid path param');
     }
 
+    if (path === '') {
+      throw new InputError('If present, the path param should not be empty');
+    }
+
     const { projectName, repoName } = req.params;
     const readme = await azureDevOpsApi.getReadme(
       host,