kubernetes-backend: refactor tests to avoid mock-fs

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>

plugins/kubernetes-backend/package.json

@@ -89,7 +89,6 @@
     "@backstage/backend-test-utils": "workspace:^",
     "@backstage/cli": "workspace:^",
     "@types/aws4": "^1.5.1",
-    "mock-fs": "^5.2.0",
     "msw": "^1.0.0",
     "supertest": "^6.1.3",
     "ws": "^8.13.0"

plugins/kubernetes-backend/src/auth/ServiceAccountStrategy.test.ts

@@ -13,8 +13,37 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+import { createMockDirectory } from '@backstage/backend-test-utils';
 import { ServiceAccountStrategy } from './ServiceAccountStrategy';
-import mockFs from 'mock-fs';
+
+const mockDir = createMockDirectory({
+  content: {
+    'token.txt': 'in-cluster-token',
+  },
+});
+
+jest.mock('@kubernetes/client-node', () => ({
+  KubeConfig: class {
+    #loaded = false;
+    loadFromCluster() {
+      this.#loaded = true;
+    }
+    getCurrentUser() {
+      if (!this.#loaded) {
+        throw new Error('loadFromCluster not called');
+      }
+      return {
+        authProvider: {
+          config: {
+            get tokenFile() {
+              return mockDir.resolve('token.txt');
+            },
+          },
+        },
+      };
+    }
+  },
+}));
 
 describe('ServiceAccountStrategy', () => {
   describe('#getCredential', () => {
@@ -32,16 +61,9 @@ describe('ServiceAccountStrategy', () => {
         token: 'from config',
       });
     });
-    describe('when serviceAccountToken is absent from config', () => {
-      afterEach(() => {
-        mockFs.restore();
-      });
 
+    describe('when serviceAccountToken is absent from config', () => {
       it('reads in-cluster token', async () => {
-        mockFs({
-          '/var/run/secrets/kubernetes.io/serviceaccount/token':
-            'in-cluster-token',
-        });
         const strategy = new ServiceAccountStrategy();
 
         const credential = await strategy.getCredential({

plugins/kubernetes-backend/src/service/KubernetesFetcher.test.ts

@@ -26,8 +26,17 @@ import {
   rest,
 } from 'msw';
 import { setupServer } from 'msw/node';
-import { setupRequestMockHandlers } from '@backstage/backend-test-utils';
-import mockFs from 'mock-fs';
+import {
+  createMockDirectory,
+  setupRequestMockHandlers,
+} from '@backstage/backend-test-utils';
+import { Config } from '@kubernetes/client-node';
+
+const mockCertDir = createMockDirectory({
+  content: {
+    'ca.crt': 'MOCKCA',
+  },
+});
 
 const OBJECTS_TO_FETCH = new Set<ObjectToFetch>([
   {
@@ -728,13 +737,7 @@ describe('KubernetesFetcher', () => {
         expect(agent.options.ca).toBeUndefined();
       });
       describe('with a CA file on disk', () => {
-        afterEach(() => {
-          mockFs.restore();
-        });
         it('should trust contents of specified caFile', async () => {
-          mockFs({
-            '/path/to/ca.crt': 'MOCKCA',
-          });
           worker.use(
             rest.get('https://localhost:9999/api/v1/pods', (req, res, ctx) =>
               res(
@@ -752,7 +755,7 @@ describe('KubernetesFetcher', () => {
               name: 'cluster1',
               url: 'https://localhost:9999',
               authMetadata: {},
-              caFile: '/path/to/ca.crt',
+              caFile: mockCertDir.resolve('ca.crt'),
             },
             credential: { type: 'bearer token', token: 'token' },
             objectTypesToFetch: new Set<ObjectToFetch>([
@@ -899,17 +902,18 @@ describe('KubernetesFetcher', () => {
     describe('Backstage running on k8s', () => {
       const initialHost = process.env.KUBERNETES_SERVICE_HOST;
       const initialPort = process.env.KUBERNETES_SERVICE_PORT;
+      const initialCaPath = Config.SERVICEACCOUNT_CA_PATH;
+
       afterEach(() => {
         process.env.KUBERNETES_SERVICE_HOST = initialHost;
         process.env.KUBERNETES_SERVICE_PORT = initialPort;
-        mockFs.restore();
+        Config.SERVICEACCOUNT_CA_PATH = initialCaPath;
       });
+
       it('makes in-cluster requests when cluster details has no token', async () => {
         process.env.KUBERNETES_SERVICE_HOST = '10.10.10.10';
         process.env.KUBERNETES_SERVICE_PORT = '443';
-        mockFs({
-          '/var/run/secrets/kubernetes.io/serviceaccount/ca.crt': '',
-        });
+        Config.SERVICEACCOUNT_CA_PATH = mockCertDir.resolve('ca.crt');
         worker.use(
           rest.get('https://10.10.10.10/api/v1/pods', (req, res, ctx) =>
             res(