test_runner: add shards support

PR-URL: #48639
Backport-PR-URL: #48797
Reviewed-By: Moshe Atlow <moshe@atlow.co.il>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>

Author: rluvaton

doc/api/cli.md

@@ -1500,6 +1500,27 @@ changes:
 Configures the test runner to only execute top level tests that have the `only`
 option set.
 
+### `--test-shard`
+
+<!-- YAML
+added: REPLACEME
+-->
+
+Test suite shard to execute in a format of `<index>/<total>`, where
+
+`index` is a positive integer, index of divided parts
+`total` is a positive integer, total of divided part
+This command will divide all tests files into `total` equal parts,
+and will run only those that happen to be in an `index` part.
+
+For example, to split your tests suite into three parts, use this:
+
+```bash
+node --test --test-shard=1/3
+node --test --test-shard=2/3
+node --test --test-shard=3/3
+```
+
 ### `--throw-deprecation`
 
 <!-- YAML
@@ -2177,6 +2198,7 @@ Node.js options that are allowed are:
 * `--test-only`
 * `--test-reporter-destination`
 * `--test-reporter`
+* `--test-shard`
 * `--throw-deprecation`
 * `--title`
 * `--tls-cipher-list`

doc/api/test.md

@@ -874,6 +874,11 @@ changes:
     If unspecified, subtests inherit this value from their parent.
     **Default:** `Infinity`.
   * `watch` {boolean} Whether to run in watch mode or not. **Default:** `false`.
+  * `shard` {Object} Running tests in a specific shard. **Default:** `undefined`.
+    * `index` {number} is a positive integer between 1 and `<total>`
+      that specifies the index of the shard to run. This option is _required_.
+    * `total` {number} is a positive integer that specifies the total number
+      of shards to split the test files to. This option is _required_.
 * Returns: {TestsStream}
 
 ```mjs

doc/node.1

@@ -424,6 +424,9 @@ The destination for the corresponding test reporter.
 Configures the test runner to only execute top level tests that have the `only`
 option set.
 .
+.It Fl -test-shard
+Test suite shard to execute in a format of <index>/<total>.
+.
 .It Fl -throw-deprecation
 Throw errors for deprecations.
 .

lib/internal/main/test_runner.js

@@ -8,6 +8,16 @@ const { isUsingInspector } = require('internal/util/inspector');
 const { run } = require('internal/test_runner/runner');
 const { setupTestReporters } = require('internal/test_runner/utils');
 const { exitCodes: { kGenericUserError } } = internalBinding('errors');
+const {
+  codes: {
+    ERR_INVALID_ARG_VALUE,
+  },
+} = require('internal/errors');
+const {
+  NumberParseInt,
+  RegExpPrototypeExec,
+  StringPrototypeSplit,
+} = primordials;
 
 prepareMainThreadExecution(false);
 markBootstrapComplete();
@@ -22,7 +32,32 @@ if (isUsingInspector()) {
   inspectPort = process.debugPort;
 }
 
-run({ concurrency, inspectPort, watch: getOptionValue('--watch'), setup: setupTestReporters })
+let shard;
+const shardOption = getOptionValue('--test-shard');
+if (shardOption) {
+  if (!RegExpPrototypeExec(/^\d+\/\d+$/, shardOption)) {
+    process.exitCode = kGenericUserError;
+
+    throw new ERR_INVALID_ARG_VALUE(
+      '--test-shard',
+      shardOption,
+      'must be in the form of <index>/<total>',
+    );
+  }
+
+  const { 0: indexStr, 1: totalStr } = StringPrototypeSplit(shardOption, '/');
+
+  const index = NumberParseInt(indexStr, 10);
+  const total = NumberParseInt(totalStr, 10);
+
+  shard = {
+    __proto__: null,
+    index,
+    total,
+  };
+}
+
+run({ concurrency, inspectPort, watch: getOptionValue('--watch'), setup: setupTestReporters, shard })
 .once('test:fail', () => {
   process.exitCode = kGenericUserError;
 });

lib/internal/test_runner/runner.js

@@ -39,10 +39,18 @@ const console = require('internal/console/global');
 const {
   codes: {
     ERR_INVALID_ARG_TYPE,
+    ERR_INVALID_ARG_VALUE,
     ERR_TEST_FAILURE,
+    ERR_OUT_OF_RANGE,
   },
 } = require('internal/errors');
-const { validateArray, validateBoolean, validateFunction } = require('internal/validators');
+const {
+  validateArray,
+  validateBoolean,
+  validateFunction,
+  validateObject,
+  validateInteger,
+} = require('internal/validators');
 const { getInspectPort, isUsingInspector, isInspectorMessage } = require('internal/util/inspector');
 const { isRegExp } = require('internal/util/types');
 const { kEmptyObject } = require('internal/util');
@@ -460,7 +468,7 @@ function run(options) {
   if (options === null || typeof options !== 'object') {
     options = kEmptyObject;
   }
-  let { testNamePatterns } = options;
+  let { testNamePatterns, shard } = options;
   const { concurrency, timeout, signal, files, inspectPort, watch, setup } = options;
 
   if (files != null) {
@@ -469,6 +477,22 @@ function run(options) {
   if (watch != null) {
     validateBoolean(watch, 'options.watch');
   }
+  if (shard != null) {
+    validateObject(shard, 'options.shard');
+    // Avoid re-evaluating the shard object in case it's a getter
+    shard = { __proto__: null, index: shard.index, total: shard.total };
+
+    validateInteger(shard.total, 'options.shard.total', 1);
+    validateInteger(shard.index, 'options.shard.index');
+
+    if (shard.index <= 0 || shard.total < shard.index) {
+      throw new ERR_OUT_OF_RANGE('options.shard.index', `>= 1 && <= ${shard.total} ("options.shard.total")`, shard.index);
+    }
+
+    if (watch) {
+      throw new ERR_INVALID_ARG_VALUE('options.shard', watch, 'shards not supported with watch mode');
+    }
+  }
   if (setup != null) {
     validateFunction(setup, 'options.setup');
   }
@@ -490,7 +514,11 @@ function run(options) {
   }
 
   const root = createTestTree({ concurrency, timeout, signal });
-  const testFiles = files ?? createTestFileList();
+  let testFiles = files ?? createTestFileList();
+
+  if (shard) {
+    testFiles = ArrayPrototypeFilter(testFiles, (_, index) => index % shard.total === shard.index - 1);
+  }
 
   let postRun = () => root.postRun();
   let filesWatcher;

src/node_options.cc

@@ -596,6 +596,10 @@ EnvironmentOptionsParser::EnvironmentOptionsParser() {
             "run tests with 'only' option set",
             &EnvironmentOptions::test_only,
             kAllowedInEnvvar);
+  AddOption("--test-shard",
+            "run test at specific shard",
+            &EnvironmentOptions::test_shard,
+            kAllowedInEnvvar);
   AddOption("--test-udp-no-try-send", "",  // For testing only.
             &EnvironmentOptions::test_udp_no_try_send);
   AddOption("--throw-deprecation",

src/node_options.h

@@ -165,6 +165,7 @@ class EnvironmentOptions : public Options {
   std::vector<std::string> test_reporter_destination;
   bool test_only = false;
   bool test_udp_no_try_send = false;
+  std::string test_shard;
   bool throw_deprecation = false;
   bool trace_atomics_wait = false;
   bool trace_deprecation = false;

test/fixtures/test-runner/shards/a.cjs

@@ -0,0 +1,4 @@
+'use strict';
+const test = require('node:test');
+
+test('a.cjs this should pass');

test/fixtures/test-runner/shards/b.cjs

@@ -0,0 +1,4 @@
+'use strict';
+const test = require('node:test');
+
+test('b.cjs this should pass');

test/fixtures/test-runner/shards/c.cjs

@@ -0,0 +1,4 @@
+'use strict';
+const test = require('node:test');
+
+test('c.cjs this should pass');