fix: surface output.postProcess execution errors instead of swallowing them

Agent-Logs-Url: https://github.com/hey-api/openapi-ts/sessions/d85588ef-7ad9-4ab7-a857-fbbe719b294f

Author: Copilot

packages/shared/src/config/output/__tests__/postprocess.test.ts

@@ -0,0 +1,145 @@
+import { sync } from 'cross-spawn';
+import { vi } from 'vitest';
+
+import { postprocessOutput } from '../postprocess';
+
+vi.mock('cross-spawn');
+
+const mockSync = vi.mocked(sync);
+
+const baseConfig = {
+  path: '/output',
+  postProcess: [],
+};
+
+const noopPostProcessors = {};
+
+describe('postprocessOutput', () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+  });
+
+  it('should not call sync when postProcess is empty', () => {
+    postprocessOutput(baseConfig, noopPostProcessors, '');
+    expect(mockSync).not.toHaveBeenCalled();
+  });
+
+  it('should call sync with command and resolved args', () => {
+    mockSync.mockReturnValue({ error: undefined, status: 0 } as any);
+
+    postprocessOutput(
+      { ...baseConfig, postProcess: [{ args: ['fmt', '{{path}}'], command: 'dprint' }] },
+      noopPostProcessors,
+      '',
+    );
+
+    expect(mockSync).toHaveBeenCalledWith('dprint', ['fmt', '/output']);
+  });
+
+  it('should replace {{path}} placeholder in args', () => {
+    mockSync.mockReturnValue({ error: undefined, status: 0 } as any);
+
+    postprocessOutput(
+      { path: '/my/output', postProcess: [{ args: ['{{path}}', '--write'], command: 'prettier' }] },
+      noopPostProcessors,
+      '',
+    );
+
+    expect(mockSync).toHaveBeenCalledWith('prettier', ['/my/output', '--write']);
+  });
+
+  it('should throw when the process fails to spawn (e.g., ENOENT)', () => {
+    const spawnError = new Error('spawnSync oxfmt ENOENT');
+    mockSync.mockReturnValue({ error: spawnError, status: null } as any);
+
+    expect(() =>
+      postprocessOutput(
+        { ...baseConfig, postProcess: [{ args: ['{{path}}'], command: 'oxfmt' }] },
+        noopPostProcessors,
+        '',
+      ),
+    ).toThrow('Post-processor "oxfmt" failed to run: spawnSync oxfmt ENOENT');
+  });
+
+  it('should throw with a custom name when the process fails to spawn', () => {
+    const spawnError = new Error('spawnSync my-formatter ENOENT');
+    mockSync.mockReturnValue({ error: spawnError, status: null } as any);
+
+    expect(() =>
+      postprocessOutput(
+        {
+          ...baseConfig,
+          postProcess: [{ args: ['{{path}}'], command: 'my-formatter', name: 'My Formatter' }],
+        },
+        noopPostProcessors,
+        '',
+      ),
+    ).toThrow('Post-processor "My Formatter" failed to run: spawnSync my-formatter ENOENT');
+  });
+
+  it('should throw when the process exits with a non-zero status code', () => {
+    mockSync.mockReturnValue({ error: undefined, status: 1, stderr: Buffer.from('') } as any);
+
+    expect(() =>
+      postprocessOutput(
+        { ...baseConfig, postProcess: [{ args: ['{{path}}'], command: 'prettier' }] },
+        noopPostProcessors,
+        '',
+      ),
+    ).toThrow('Post-processor "prettier" exited with code 1');
+  });
+
+  it('should include stderr output in error message when process fails', () => {
+    mockSync.mockReturnValue({
+      error: undefined,
+      status: 2,
+      stderr: Buffer.from('error: file not found'),
+    } as any);
+
+    expect(() =>
+      postprocessOutput(
+        { ...baseConfig, postProcess: [{ args: ['{{path}}'], command: 'biome' }] },
+        noopPostProcessors,
+        '',
+      ),
+    ).toThrow('Post-processor "biome" exited with code 2:\nerror: file not found');
+  });
+
+  it('should skip unknown string preset processors', () => {
+    postprocessOutput({ ...baseConfig, postProcess: ['unknown-preset'] }, noopPostProcessors, '');
+    expect(mockSync).not.toHaveBeenCalled();
+  });
+
+  it('should resolve and run string preset processors', () => {
+    mockSync.mockReturnValue({ error: undefined, status: 0 } as any);
+
+    const processors = {
+      prettier: { args: ['--write', '{{path}}'], command: 'prettier', name: 'Prettier' },
+    };
+
+    postprocessOutput({ ...baseConfig, postProcess: ['prettier'] }, processors, '');
+
+    expect(mockSync).toHaveBeenCalledWith('prettier', ['--write', '/output']);
+  });
+
+  it('should stop processing and throw on first failure', () => {
+    const spawnError = new Error('ENOENT');
+    mockSync.mockReturnValue({ error: spawnError, status: null } as any);
+
+    expect(() =>
+      postprocessOutput(
+        {
+          ...baseConfig,
+          postProcess: [
+            { args: ['{{path}}'], command: 'first' },
+            { args: ['{{path}}'], command: 'second' },
+          ],
+        },
+        noopPostProcessors,
+        '',
+      ),
+    ).toThrow('Post-processor "first" failed to run: ENOENT');
+
+    expect(mockSync).toHaveBeenCalledTimes(1);
+  });
+});

packages/shared/src/config/output/postprocess.ts

@@ -60,6 +60,18 @@ export function postprocessOutput(
     const args = resolved.args.map((arg) => arg.replace('{{path}}', config.path));
 
     console.log(`${jobPrefix}🧹 Running ${colors.cyanBright(name)}`);
-    sync(resolved.command, args);
+    const result = sync(resolved.command, args);
+
+    if (result.error) {
+      throw new Error(`Post-processor "${name}" failed to run: ${result.error.message}`);
+    }
+
+    if (result.status !== 0) {
+      const stderr = result.stderr?.toString().trim();
+      const message = stderr
+        ? `Post-processor "${name}" exited with code ${result.status}:\n${stderr}`
+        : `Post-processor "${name}" exited with code ${result.status}`;
+      throw new Error(message);
+    }
   }
 }