nice testing

.vscode/launch.json

@@ -5,19 +5,15 @@
   "version": "0.2.0",
   "configurations": [
     {
-      // Has convenient settings for attaching to a NodeJS process for debugging purposes
-      // that are NOT the default and otherwise every developers has to configure for
-      // themselves again and again.
       "type": "node",
-      "request": "attach",
-      "name": "Attach to NodeJS",
-      // If we don't do this, every step-into into an async function call will go into
-      // NodeJS internals which are hard to step out of.
-      "skipFiles": [
-        "<node_internals>/**"
-      ],
-      // Saves some button-pressing latency on attaching
-      "stopOnEntry": false
+      "request": "launch",
+      "args": ["jest", "--runTestsByPath", "/Users/bergjak/workplace/CDK/aws-cdk/packages/aws-cdk-lib/aws-lambda/test/code.test.ts"],
+      "name": "debug unit test",
+      "program": "/opt/homebrew/bin/yarn",
+      "cwd": "/Users/bergjak/workplace/CDK/aws-cdk/packages/aws-cdk-lib",
+      "console": "integratedTerminal",
+      "sourceMaps": true,
+      "skipFiles": [ "<node_internals>/**/*" ],
     }
   ]
 }

packages/aws-cdk-lib/aws-lambda/lib/code.ts

@@ -84,7 +84,7 @@ export abstract class Code {
       : spawnSync(cmd, commandArguments, commandOptions);
 
     if (proc.error) {
-      throw proc.error;
+      throw new Error(`Failed to execute custom command: ${proc.error}`);
     }
     if (proc.status !== 0) {
       throw new Error(`${command.join(' ')} exited with status: ${proc.status}\n\nstdout: ${proc.stdout?.toString().trim()}\n\nstderr: ${proc.stderr?.toString().trim()}`);

packages/aws-cdk-lib/aws-lambda/test/code.test.ts

@@ -1,3 +1,4 @@
+import * as child_process from 'child_process';
 import * as path from 'path';
 import { Match, Template } from '../../assertions';
 import * as ecr from '../../aws-ecr';
@@ -15,6 +16,78 @@ describe('code', () => {
     });
   });
 
+  describe('lambda.Code.fromCustomCommand', () => {
+    let spawnSyncMock: jest.SpyInstance;
+    beforeEach(() => {
+      spawnSyncMock = jest.spyOn(child_process, 'spawnSync').mockReturnValue({
+        status: 0,
+        stderr: Buffer.from('stderr'),
+        stdout: Buffer.from('stdout'),
+        pid: 123,
+        output: ['stdout', 'stderr'],
+        signal: null,
+      });
+    });
+    afterEach(() => {
+      jest.restoreAllMocks();
+    });
+
+    test('fails if command is empty', () => {
+      // GIVEN
+      const command = [];
+
+      // THEN
+      expect(() => lambda.Code.fromCustomCommand('', command)).toThrow('command must contain at least one argument. For example, ["node", "buildFile.js"].');
+    });
+    test('properly splices arguments', () => {
+      // GIVEN
+      const command = 'node is a great command, wow'.split(' ');
+      lambda.Code.fromCustomCommand('', command);
+
+      // THEN
+      expect(spawnSyncMock).toHaveBeenCalledWith(
+        'node',
+        ['is', 'a', 'great', 'command,', 'wow'],
+      );
+    });
+    test('properly splices arguments when commandOptions are included', () => {
+      // GIVEN
+      const command = 'node is a great command, wow'.split(' ');
+      const commandOptions = { cwd: '/tmp', env: { SOME_KEY: 'SOME_VALUE' } };
+      lambda.Code.fromCustomCommand('', command, commandOptions);
+
+      // THEN
+      expect(spawnSyncMock).toHaveBeenCalledWith(
+        'node',
+        ['is', 'a', 'great', 'command,', 'wow'],
+        commandOptions,
+      );
+    });
+    test('throws custom error message when spawnSync errors', () => {
+      // GIVEN
+      jest.restoreAllMocks(); // use the real spawnSync, which doesn't work in unit tests.
+      const command = ['whatever'];
+
+      // THEN
+      expect(() => lambda.Code.fromCustomCommand('', command)).toThrow(/Failed to execute custom command: .*/);
+    });
+    test('throws custom error message when spawnSync exits with non-zero status code', () => {
+      // GIVEN
+      const command = ['whatever'];
+      spawnSyncMock = jest.spyOn(child_process, 'spawnSync').mockReturnValue({
+        status: 1,
+        stderr: Buffer.from('stderr'),
+        stdout: Buffer.from('stdout'),
+        pid: 123,
+        output: ['stdout', 'stderr'],
+        signal: null,
+      });
+
+      // THEN
+      expect(() => lambda.Code.fromCustomCommand('', command)).toThrow('whatever exited with status: 1\n\nstdout: stdout\n\nstderr: stderr');
+    });
+  });
+
   describe('lambda.Code.fromAsset', () => {
     test('fails if path is empty', () => {
       // GIVEN