cli: add option to reject network requets in frontend tests

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

packages/cli/config/jest.js

@@ -23,6 +23,14 @@ const paths = require('@backstage/cli-common').findPaths(process.cwd());
 
 const SRC_EXTS = ['ts', 'js', 'tsx', 'jsx', 'mts', 'cts', 'mjs', 'cjs'];
 
+const FRONTEND_ROLES = [
+  'frontend',
+  'web-library',
+  'common-library',
+  'frontend-plugin',
+  'frontend-plugin-module',
+];
+
 const envOptions = {
   oldTests: Boolean(process.env.BACKSTAGE_OLD_TESTS),
 };
@@ -121,24 +129,13 @@ const transformIgnorePattern = [
 
 // Provides additional config that's based on the role of the target package
 function getRoleConfig(role) {
-  switch (role) {
-    case 'frontend':
-    case 'web-library':
-    case 'common-library':
-    case 'frontend-plugin':
-    case 'frontend-plugin-module':
-      return { testEnvironment: require.resolve('jest-environment-jsdom') };
-    case 'cli':
-    case 'backend':
-    case 'node-library':
-    case 'backend-plugin':
-    case 'backend-plugin-module':
-    default:
-      return { testEnvironment: require.resolve('jest-environment-node') };
+  if (FRONTEND_ROLES.includes(role)) {
+    return { testEnvironment: require.resolve('jest-environment-jsdom') };
   }
+  return { testEnvironment: require.resolve('jest-environment-node') };
 }
 
-async function getProjectConfig(targetPath, extraConfig) {
+async function getProjectConfig(targetPath, extraConfig, extraOptions) {
   const configJsPath = path.resolve(targetPath, 'jest.config.js');
   const configTsPath = path.resolve(targetPath, 'jest.config.ts');
   // If the package has it's own jest config, we use that instead.
@@ -232,6 +229,17 @@ async function getProjectConfig(targetPath, extraConfig) {
 
   options.setupFilesAfterEnv = options.setupFilesAfterEnv || [];
 
+  if (
+    extraOptions.rejectFrontendNetworkRequests &&
+    FRONTEND_ROLES.includes(pkgJson.backstage?.role)
+  ) {
+    // By adding this first we ensure that it's possible to for example override
+    // fetch with a mock in a custom setup file
+    options.setupFilesAfterEnv.unshift(
+      require.resolve('./jestRejectNetworkRequests.js'),
+    );
+  }
+
   if (options.testEnvironment === require.resolve('jest-environment-jsdom')) {
     // FIXME https://github.com/jsdom/jsdom/issues/1724
     options.setupFilesAfterEnv.unshift(require.resolve('cross-fetch/polyfill'));
@@ -276,21 +284,31 @@ async function getRootConfig() {
     collectCoverageFrom: ['**/*.{js,jsx,ts,tsx,mjs,cjs}', '!**/*.d.ts'],
   };
 
+  const { rejectFrontendNetworkRequests, ...rootOptions } =
+    rootPkgJson.jest ?? {};
+  const extraRootOptions = {
+    rejectFrontendNetworkRequests,
+  };
+
   const workspacePatterns =
     rootPkgJson.workspaces && rootPkgJson.workspaces.packages;
 
   // Check if we're running within a specific monorepo package. In that case just get the single project config.
   if (!workspacePatterns || paths.targetRoot !== paths.targetDir) {
-    return getProjectConfig(paths.targetDir, {
-      ...baseCoverageConfig,
-      ...(rootPkgJson.jest ?? {}),
-    });
+    return getProjectConfig(
+      paths.targetDir,
+      {
+        ...baseCoverageConfig,
+        ...rootOptions,
+      },
+      extraRootOptions,
+    );
   }
 
   const globalRootConfig = { ...baseCoverageConfig };
   const globalProjectConfig = {};
 
-  for (const [key, value] of Object.entries(rootPkgJson.jest ?? {})) {
+  for (const [key, value] of Object.entries(rootOptions)) {
     if (projectConfigKeys.includes(key)) {
       globalProjectConfig[key] = value;
     } else {
@@ -321,10 +339,14 @@ async function getRootConfig() {
         testScript?.includes('backstage-cli test') ||
         testScript?.includes('backstage-cli package test');
       if (testScript && isSupportedTestScript) {
-        return await getProjectConfig(projectPath, {
-          ...globalProjectConfig,
-          displayName: packageData.name,
-        });
+        return await getProjectConfig(
+          projectPath,
+          {
+            ...globalProjectConfig,
+            displayName: packageData.name,
+          },
+          extraRootOptions,
+        );
       }
 
       return undefined;

packages/cli/config/jestRejectNetworkRequests.js

@@ -0,0 +1,59 @@
+/*
+ * Copyright 2024 The Backstage Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+const http = require('http');
+const https = require('https');
+
+const errorMessage = 'Network requests are not allowed in tests';
+
+const origHttpAgent = http.globalAgent;
+const origHttpsAgent = https.globalAgent;
+const origFetch = global.fetch;
+const origXMLHttpRequest = global.fetch;
+
+http.globalAgent = new http.Agent({
+  lookup() {
+    throw new Error(errorMessage);
+  },
+});
+
+https.globalAgent = new https.Agent({
+  lookup() {
+    throw new Error(errorMessage);
+  },
+});
+
+if (global.fetch) {
+  global.fetch = async () => {
+    throw new Error(errorMessage);
+  };
+}
+
+if (global.XMLHttpRequest) {
+  global.XMLHttpRequest = class {
+    constructor() {
+      throw new Error(errorMessage);
+    }
+  };
+}
+
+// Reset overrides after each suite to make sure we don't pollute the test environment
+afterAll(() => {
+  http.globalAgent = origHttpAgent;
+  https.globalAgent = origHttpsAgent;
+  global.fetch = origFetch;
+  global.XMLHttpRequest = origXMLHttpRequest;
+});