test: make test-v8-coverage.js more strict

Update the coverage test to verify that nothing is printed to
stderr (which happens when coverage errors happen). Also add a
test case to verify that non-absolute coverage paths work.

PR-URL: #25289
Fixes: #25287
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Gus Caplan <me@gus.host>
Reviewed-By: Yuta Hiroto <hello@hiroppy.me>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

test/parallel/test-v8-coverage.js

@@ -23,6 +23,7 @@ function nextdir() {
  require.resolve('../fixtures/v8-coverage/basic')
  ], { env: { ...process.env, NODE_V8_COVERAGE: coverageDirectory } });
  assert.strictEqual(output.status, 0);
+ assert.strictEqual(output.stderr.toString(), '');
  const fixtureCoverage = getFixtureCoverage('basic.js', coverageDirectory);
  assert.ok(fixtureCoverage);
  // first branch executed.
@@ -38,6 +39,7 @@ function nextdir() {
  require.resolve('../fixtures/v8-coverage/exit-1')
  ], { env: { ...process.env, NODE_V8_COVERAGE: coverageDirectory } });
  assert.strictEqual(output.status, 1);
+ assert.strictEqual(output.stderr.toString(), '');
  const fixtureCoverage = getFixtureCoverage('exit-1.js', coverageDirectory);
  assert.ok(fixtureCoverage, 'coverage not found for file');
  // first branch executed.
@@ -55,6 +57,7 @@ function nextdir() {
  if (!common.isWindows) {
  assert.strictEqual(output.signal, 'SIGINT');
  }
+ assert.strictEqual(output.stderr.toString(), '');
  const fixtureCoverage = getFixtureCoverage('sigint.js', coverageDirectory);
  assert.ok(fixtureCoverage);
  // first branch executed.
@@ -70,6 +73,7 @@ function nextdir() {
  require.resolve('../fixtures/v8-coverage/spawn-subprocess')
  ], { env: { ...process.env, NODE_V8_COVERAGE: coverageDirectory } });
  assert.strictEqual(output.status, 0);
+ assert.strictEqual(output.stderr.toString(), '');
  const fixtureCoverage = getFixtureCoverage('subprocess.js',
  coverageDirectory);
  assert.ok(fixtureCoverage);
@@ -86,6 +90,7 @@ function nextdir() {
  require.resolve('../fixtures/v8-coverage/worker')
  ], { env: { ...process.env, NODE_V8_COVERAGE: coverageDirectory } });
  assert.strictEqual(output.status, 0);
+ assert.strictEqual(output.stderr.toString(), '');
  const fixtureCoverage = getFixtureCoverage('subprocess.js',
  coverageDirectory);
  assert.ok(fixtureCoverage);
@@ -102,6 +107,7 @@ function nextdir() {
  require.resolve('../fixtures/v8-coverage/spawn-subprocess-no-cov')
  ], { env: { ...process.env, NODE_V8_COVERAGE: coverageDirectory } });
  assert.strictEqual(output.status, 0);
+ assert.strictEqual(output.stderr.toString(), '');
  const fixtureCoverage = getFixtureCoverage('subprocess.js',
  coverageDirectory);
  assert.strictEqual(fixtureCoverage, undefined);
@@ -114,13 +120,35 @@ function nextdir() {
  require.resolve('../fixtures/v8-coverage/async-hooks')
  ], { env: { ...process.env, NODE_V8_COVERAGE: coverageDirectory } });
  assert.strictEqual(output.status, 0);
+ assert.strictEqual(output.stderr.toString(), '');
  const fixtureCoverage = getFixtureCoverage('async-hooks.js',
  coverageDirectory);
  assert.ok(fixtureCoverage);
  // first branch executed.
  assert.strictEqual(fixtureCoverage.functions[1].ranges[0].count, 1);
 }
 
+// Outputs coverage when the coverage directory is not absolute.
+{
+ const coverageDirectory = nextdir();
+ const absoluteCoverageDirectory = path.join(tmpdir.path, coverageDirectory);
+ const output = spawnSync(process.execPath, [
+ require.resolve('../fixtures/v8-coverage/basic')
+ ], {
+ cwd: tmpdir.path,
+ env: { ...process.env, NODE_V8_COVERAGE: coverageDirectory }
+ });
+ assert.strictEqual(output.status, 0);
+ assert.strictEqual(output.stderr.toString(), '');
+ const fixtureCoverage = getFixtureCoverage('basic.js',
+ absoluteCoverageDirectory);
+ assert.ok(fixtureCoverage);
+ // first branch executed.
+ assert.strictEqual(fixtureCoverage.functions[1].ranges[0].count, 1);
+ // second branch did not execute.
+ assert.strictEqual(fixtureCoverage.functions[1].ranges[1].count, 0);
+}
+
 // Extracts the coverage object for a given fixture name.
 function getFixtureCoverage(fixtureFile, coverageDirectory) {
  const coverageFiles = fs.readdirSync(coverageDirectory);