feat: allow running ngcc with specific tsconfig path

src/config/global-setup.ts

@@ -1,4 +1,5 @@
 import type { Config } from '@jest/types';
+import type { TsJestGlobalOptions } from 'ts-jest/dist/types';
 
 import { runNgccJestProcessor } from '../utils/ngcc-jest-processor';
 
@@ -7,11 +8,13 @@ interface NgJestProjectConfig extends Omit<Config.ProjectConfig, 'globals'> {
     ngJest?: {
       skipNgcc: boolean;
     };
+    tsJest?: TsJestGlobalOptions;
   };
 }
 
-export = async (_globalConfig: Config.GlobalConfig, projectConfig: NgJestProjectConfig) => {
-  if (!projectConfig.globals.ngJest?.skipNgcc) {
-    runNgccJestProcessor();
+export = async (_globalConfig: Config.GlobalConfig, { globals }: NgJestProjectConfig) => {
+  if (!globals.ngJest?.skipNgcc) {
+    const tsconfig = globals.tsJest?.tsconfig;
+    runNgccJestProcessor(typeof tsconfig === 'string' ? tsconfig : undefined);
   }
 };

src/utils/__snapshots__/ngcc-jest-processor.spec.ts.snap

@@ -0,0 +1,31 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`ngcc-jest-processor should execute @angular/compiler-cli ngcc with tsconfig path foo 1`] = `
+Array [
+  "/node_modules/@angular/compiler-cli/bundles/ngcc/main-ngcc.js",
+  "--source",
+  "/node_modules/",
+  "--properties",
+  "es2015",
+  "main",
+  "--first-only",
+  "false",
+  "--async",
+  "--tsconfig",
+  "foo",
+]
+`;
+
+exports[`ngcc-jest-processor should execute @angular/compiler-cli ngcc with tsconfig path undefined 1`] = `
+Array [
+  "/node_modules/@angular/compiler-cli/bundles/ngcc/main-ngcc.js",
+  "--source",
+  "/node_modules/",
+  "--properties",
+  "es2015",
+  "main",
+  "--first-only",
+  "false",
+  "--async",
+]
+`;

src/utils/ngcc-jest-processor.spec.ts

@@ -0,0 +1,20 @@
+import childProcess from 'child_process';
+
+import { runNgccJestProcessor } from './ngcc-jest-processor';
+
+describe('ngcc-jest-processor', () => {
+  test.each(['foo', undefined])('should execute @angular/compiler-cli ngcc with tsconfig path %s', (tsconfigPath) => {
+    const mockedSpawnSync = (childProcess.spawnSync = jest.fn().mockReturnValueOnce({
+      status: 0,
+    }));
+
+    runNgccJestProcessor(tsconfigPath);
+
+    expect(childProcess.spawnSync).toHaveBeenCalled();
+    expect(mockedSpawnSync.mock.calls[0][0]).toBe(process.execPath);
+    const ngccArgs = (mockedSpawnSync.mock.calls[0][1] as string[]).map((arg) => arg.replace(process.cwd(), ''));
+    expect(ngccArgs).toMatchSnapshot();
+
+    jest.restoreAllMocks();
+  });
+});

src/utils/ngcc-jest-processor.ts

@@ -20,34 +20,35 @@ function findNodeModulesDirectory(): string {
 
 const nodeModuleDirPath = findNodeModulesDirectory();
 
-export const runNgccJestProcessor = (): void => {
+export const runNgccJestProcessor = (tsconfigPath: string | undefined): void => {
   if (nodeModuleDirPath) {
     process.stdout.write('\nngcc-jest-processor: running ngcc\n');
+
+    const ngccBaseArgs = [
+      ngccPath,
+      '--source' /** basePath */,
+      nodeModuleDirPath,
+      '--properties' /** propertiesToConsider */,
+      /**
+       * There are various properties: fesm2015, fesm5, es2015, esm2015, esm5, main, module, browser to choose from.
+       * Normally, Jest requires `umd`. If running Jest in ESM mode, Jest will require both `umd` + `esm2015`.
+       */
+      ...['es2015', 'main'],
+      '--first-only' /** compileAllFormats */,
+      'false', // make sure that `ngcc` runs on subfolders as well
+      '--async',
+    ];
+    if (tsconfigPath) {
+      ngccBaseArgs.push(...['--tsconfig', tsconfigPath]);
+    }
     // We spawn instead of using the API because:
     // - NGCC Async uses clustering which is problematic when used via the API which means
     // that we cannot setup multiple cluster masters with different options.
     // - We will not be able to have concurrent builds otherwise Ex: App-Shell,
     // as NGCC will create a lock file for both builds and it will cause builds to fails.
-    const { status, error } = spawnSync(
-      process.execPath,
-      [
-        ngccPath,
-        '--source' /** basePath */,
-        nodeModuleDirPath,
-        '--properties' /** propertiesToConsider */,
-        /**
-         * There are various properties: fesm2015, fesm5, es2015, esm2015, esm5, main, module, browser to choose from.
-         * Normally, Jest requires `umd`. If running Jest in ESM mode, Jest will require both `umd` + `esm2015`.
-         */
-        ...['es2015', 'main'],
-        '--first-only' /** compileAllFormats */,
-        'false', // make sure that `ngcc` runs on subfolders as well
-        '--async',
-      ],
-      {
-        stdio: ['inherit', process.stderr, process.stderr],
-      },
-    );
+    const { status, error } = spawnSync(process.execPath, ngccBaseArgs, {
+      stdio: ['inherit', process.stderr, process.stderr],
+    });
     if (status !== 0) {
       const errorMessage: string = error?.message ?? '';