fix(rstack): isolate related-test JSON output

Author: ScriptedAlchemy

packages/rstack/src/relatedTests.ts

@@ -1,4 +1,6 @@
 import { execFile } from 'node:child_process';
+import { mkdtemp, readFile, rm } from 'node:fs/promises';
+import os from 'node:os';
 import path from 'node:path';
 import type { RelatedTestRequest } from '@rstackjs/context';
 
@@ -36,24 +38,34 @@ const resolveRelatedTests = async (
   request: RelatedTestRequest,
   dependencies: RelatedTestResolverDependencies = {},
 ): Promise<string[]> => {
-  const args = [
-    path.join(import.meta.dirname, '..', 'bin', 'rs.js'),
-    'test',
-    'list',
-    '--related',
-    ...request.sources,
-    '--filesOnly',
-    '--json',
-    ...(request.configPath === undefined ? [] : ['--config', request.configPath]),
-  ];
-  const { stdout, stderr } = await (dependencies.runCli ?? runCli)({
-    cwd: request.packageRoot,
-    args,
-  });
+  const outputDirectory = await mkdtemp(path.join(os.tmpdir(), 'rstack-related-tests-'));
+  const outputFile = path.join(outputDirectory, 'tests.json');
+  let source: string;
+  let stderr: string;
+  try {
+    const args = [
+      path.join(import.meta.dirname, '..', 'bin', 'rs.js'),
+      'test',
+      'list',
+      '--related',
+      ...request.sources,
+      '--filesOnly',
+      '--json',
+      outputFile,
+      ...(request.configPath === undefined ? [] : ['--config', request.configPath]),
+    ];
+    ({ stderr } = await (dependencies.runCli ?? runCli)({
+      cwd: request.packageRoot,
+      args,
+    }));
+    source = await readFile(outputFile, 'utf8');
+  } finally {
+    await rm(outputDirectory, { force: true, recursive: true });
+  }
 
   let parsed: unknown;
   try {
-    parsed = JSON.parse(stdout);
+    parsed = JSON.parse(source);
   } catch {
     throw new Error(
       `Rstest related-test listing returned invalid JSON${stderr.length === 0 ? '.' : `: ${stderr.trim()}`}`,

packages/rstack/tests/context/relatedTests.test.ts

@@ -1,7 +1,14 @@
+import { writeFile } from 'node:fs/promises';
 import path from 'node:path';
 import { expect, test } from '@rstest/core';
 import { resolveRelatedTests } from '../../src/relatedTests.ts';
 
+const getOutputFile = (args: string[]): string => {
+  const outputFile = args[args.indexOf('--json') + 1];
+  if (outputFile === undefined) throw new Error('Missing related-test output file.');
+  return outputFile;
+};
+
 test('lists related tests through the current Rstack CLI and normalizes its JSON result', async () => {
   const calls: unknown[] = [];
   const packageRoot = path.resolve('/workspace/packages/app');
@@ -16,13 +23,14 @@ test('lists related tests through the current Rstack CLI and normalizes its JSON
     {
       runCli: (request) => {
         calls.push(request);
-        return Promise.resolve({
-          stdout: JSON.stringify([
+        const outputFile = getOutputFile(request.args);
+        return writeFile(
+          outputFile,
+          JSON.stringify([
             { file: 'tests/index.test.ts', type: 'file' },
             { file: path.join(packageRoot, 'tests/index.test.ts'), type: 'file' },
           ]),
-          stderr: '',
-        });
+        ).then(() => ({ stdout: 'config log that is not JSON', stderr: '' }));
       },
     },
   );
@@ -38,6 +46,7 @@ test('lists related tests through the current Rstack CLI and normalizes its JSON
         path.join(packageRoot, 'src/index.ts'),
         '--filesOnly',
         '--json',
+        expect.stringMatching(/rstack-related-tests-/u),
         '--config',
         configPath,
       ],
@@ -50,7 +59,13 @@ test('reports invalid related-test JSON as an Rstest list failure', async () =>
   await expect(
     resolveRelatedTests(
       { packageRoot: '/workspace', sources: ['/workspace/src/index.ts'] },
-      { runCli: () => Promise.resolve({ stdout: 'not json', stderr: 'list failed' }) },
+      {
+        runCli: (request) =>
+          writeFile(getOutputFile(request.args), 'not json').then(() => ({
+            stdout: '',
+            stderr: 'list failed',
+          })),
+      },
     ),
   ).rejects.toThrow('Rstest related-test listing returned invalid JSON');
 });