test: Workaround for Jest dynamic import issues

Dynamic imports cause segmentation faults with Jest:
nodejs/node#35889.
We work around this by handling imports in IdentityProviderFactory
differently when Jest is running.
For unit tests we use a different tsconfig
that transpiles dynamic imports differently,
as those are also used in AppRunner.

jest.config.js

@@ -46,7 +46,7 @@ const esModules = [
 module.exports = {
   transform: {
     '^.+\\.ts$': [ 'ts-jest', {
-        tsconfig: '<rootDir>/tsconfig.json',
+        tsconfig: '<rootDir>/test/tsconfig.json',
         diagnostics: false,
         isolatedModules: true,
     }],

src/identity/configuration/IdentityProviderFactory.ts

@@ -144,9 +144,23 @@ export class IdentityProviderFactory implements ProviderFactory {
     // Render errors with our own error handler
     this.configureErrors(config);
 
-    // Allow provider to interpret reverse proxy headers.
     // As oidc-provider is an ESM package and CSS is CJS, we have to use a dynamic import here.
-    const provider = new (await import('oidc-provider')).default(this.baseUrl, config);
+    // Unfortunately, there is a Node/Jest bug that causes segmentation faults when doing such an import in Jest:
+    // https://github.com/nodejs/node/issues/35889
+    // To work around that, we do the import differently, in case we are in a Jest test run.
+    // This can be detected via the env variables: https://jestjs.io/docs/environment-variables.
+    // There have been reports of `JEST_WORKER_ID` being undefined, so to be sure we check both.
+    let ctr: { default: new(issuer: string, configuration?: Configuration) => Provider };
+    // eslint-disable-next-line no-process-env
+    if (process.env.JEST_WORKER_ID ?? process.env.NODE_ENV === 'test') {
+      // eslint-disable-next-line no-undef
+      ctr = jest.requireActual('oidc-provider');
+    } else {
+      ctr = await import('oidc-provider');
+    }
+    const provider = new ctr.default(this.baseUrl, config);
+
+    // Allow provider to interpret reverse proxy headers.
     provider.proxy = true;
 
     this.captureErrorResponses(provider);

test/tsconfig.json

@@ -1,5 +1,8 @@
 {
   "extends": "../tsconfig.json",
+  "compilerOptions": {
+    "moduleResolution": "node"
+  },
   "include": [
     "."
   ]

test/unit/identity/configuration/IdentityProviderFactory.test.ts

@@ -36,6 +36,8 @@ const routes = {
 };
 
 describe('An IdentityProviderFactory', (): void => {
+  let jestWorkerId: string | undefined;
+  let nodeEnv: string | undefined;
   let baseConfig: Configuration;
   const baseUrl = 'http://example.com/foo/';
   const oidcPath = '/oidc';
@@ -52,8 +54,24 @@ describe('An IdentityProviderFactory', (): void => {
   let responseWriter: jest.Mocked<ResponseWriter>;
   let factory: IdentityProviderFactory;
 
+  beforeAll(async(): Promise<void> => {
+    // We need to fool the IDP factory into thinking we are not in a test run,
+    // otherwise we can't mock the oidc-provider library due to the workaround in the code there.
+    jestWorkerId = process.env.JEST_WORKER_ID;
+    nodeEnv = process.env.NODE_ENV;
+    delete process.env.JEST_WORKER_ID;
+    delete process.env.NODE_ENV;
+  });
+
+  afterAll(async(): Promise<void> => {
+    process.env.JEST_WORKER_ID = jestWorkerId;
+    process.env.NODE_ENV = nodeEnv;
+  });
+
   beforeEach(async(): Promise<void> => {
-    baseConfig = { claims: { webid: [ 'webid', 'client_webid' ]}};
+    // Disabling devInteractions to prevent warnings when testing the path
+    // where we use the actual library instead of a mock.
+    baseConfig = { claims: { webid: [ 'webid', 'client_webid' ]}, features: { devInteractions: { enabled: false }}};
 
     ctx = {
       method: 'GET',
@@ -307,4 +325,12 @@ describe('An IdentityProviderFactory', (): void => {
     expect(oldAccept).toHaveBeenCalledTimes(1);
     expect(oldAccept).toHaveBeenLastCalledWith('something');
   });
+
+  it('avoids dynamic imports when testing with Jest.', async(): Promise<void> => {
+    // Reset the env variable, so we can test the path where the dynamic import is not used
+    process.env.JEST_WORKER_ID = jestWorkerId;
+    const provider = await factory.getProvider() as any;
+    // We don't define this in our mock
+    expect(provider.app).toBeDefined();
+  });
 });