How do I rerun one nested node:test case by name?

Use node --test with --test-name-pattern and an explicit test-file path. For an ordinary nested t.test() case, the filter must allow its enclosing test to run too. Node’s documentation warns that matching a child alone is insufficient if its parent does not match. Node.js filtering documentation

For the example below, select the accepts integers case and its parent with:

node --test --test-name-pattern="^number parsing$" --test-name-pattern="accepts integers$" test/parser.test.mjs

The first pattern matches the parent exactly. The second matches the desired child’s name suffix. Neither matches the sibling case in this example.

Start with a parent and two distinguishable cases

Save this as test/parser.test.mjs:

import test from 'node:test';
import assert from 'node:assert/strict';

test('number parsing', async (t) => {
  await t.test('accepts integers', () => {
    assert.equal(Number('42'), 42);
  });

  await t.test('returns NaN for text', () => {
    assert.ok(Number.isNaN(Number('hello')));
  });
});

The enclosing callback creates the two subtests, with each subtest call awaited, following the structure of Node’s documented nested-test example. Node.js filtering documentation

Select the parent and only the intended child

Name patterns are JavaScript regular expressions. Repeated --test-name-pattern options provide alternative matches: a test name does not have to match every expression. Node’s documentation demonstrates using separate pattern options to select a parent and its children. Node.js filtering documentation

For this file:

• ^number parsing$ matches the enclosing test exactly.
• accepts integers$ matches the desired child-name suffix, including when preceded by an ancestor name.
• returns NaN for text matches neither expression.

You can express the same selection with regex alternation:

node --test --test-name-pattern="^number parsing$|accepts integers$" test/parser.test.mjs

The parent expression’s anchors are deliberate. A bare number parsing expression can also match that text inside a longer hierarchical name; it is not an exact parent-only match.

For deeper ordinary t.test() nesting, allow every enclosing test to run, not just the immediate parent.

Distinguish repeated case names in suites

A child-name suffix is not necessarily unique across a file. When different branches reuse a case name, use the hierarchy to distinguish them.

Node’s documentation demonstrates this with describe()/it() suites: prefix the case name with all its ancestor names, separated by spaces. For example, if suites named decimal and hexadecimal both contain it('parses input', ...), select the decimal case with:

node --test --test-name-pattern="^decimal parses input$" test/parser-suites.test.mjs

This applies the documented full-name selection technique, with anchors added for an exact match. It is a suite example—not a reason to omit the enclosing ordinary test from the earlier t.test() command. Node.js filtering documentation

Know what a focused rerun still executes

A name filter is not complete execution isolation:

• Specify the file explicitly. Name patterns do not change which files the runner executes.
• Expect the enclosing ordinary test to execute. In the t.test() example, its callback creates the selected child.
• Expect applicable hooks to run. Node runs corresponding hooks, such as beforeEach(), for executed tests.
• Check skip filters. If both --test-name-pattern and --test-skip-pattern are supplied, a test must match the inclusion filter and avoid exclusion by the skip filter.

These behaviors follow the filtering reference.

The CLI reference records --test-name-pattern as added in Node.js v18.11.0. That is the option’s introduction version, not a guarantee that every current nested-filter example behaves identically on older releases. The commands here follow the current documentation; consult your runtime’s version-specific reference when working with an older version. Node.js CLI reference