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src: dump snapshot source with node:generate_default_snapshot_source #61101

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src: dump snapshot source with node:generate_default_snapshot_source #61101

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cc1ac1e
src: dump snapshot source with node:generate_default_snapshot_source
joyeecheung Dec 17, 2025
b6ace85
fixup! src: dump snapshot source with node:generate_default_snapshot_…
joyeecheung Dec 19, 2025
09ccbcf
fixup! fixup! src: dump snapshot source with node:generate_default_sn…
joyeecheung Dec 19, 2025
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15 changes: 15 additions & 0 deletions src/node.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -1374,6 +1374,21 @@ ExitCode GenerateAndWriteSnapshotData(const SnapshotData** snapshot_data_ptr,
DCHECK(snapshot_config.builder_script_path.has_value());
const std::string& builder_script =
snapshot_config.builder_script_path.value();

// For the special builder node:generate_default_snapshot_source, generate
// the snapshot as C++ source and write it to snapshot.cc (for testing).
if (builder_script == "node:generate_default_snapshot_source") {
// Reset to empty to generate from scratch.
snapshot_config.builder_script_path = {};
exit_code =
node::SnapshotBuilder::GenerateAsSource("snapshot.cc",
args_maybe_patched,
result->exec_args(),
snapshot_config,
true /* use_array_literals */);
return exit_code;
}

// node:embedded_snapshot_main indicates that we are using the
// embedded snapshot and we are not supposed to clean it up.
if (builder_script == "node:embedded_snapshot_main") {
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35 changes: 6 additions & 29 deletions test/parallel/test-snapshot-reproducible.js
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Original file line number Diff line number Diff line change
Expand Up @@ -21,7 +21,7 @@ function generateSnapshot() {
'--random_seed=42',
'--predictable',
'--build-snapshot',
'node:generate_default_snapshot',
'node:generate_default_snapshot_source',
],
{
env: { ...process.env, NODE_DEBUG_NATIVE: 'SNAPSHOT_SERDES' },
Expand All @@ -38,33 +38,10 @@ function generateSnapshot() {
},
}
);
const blobPath = tmpdir.resolve('snapshot.blob');
return fs.readFileSync(blobPath);
const outputPath = tmpdir.resolve('snapshot.cc');
return fs.readFileSync(outputPath, 'utf-8').split('\n');
}

const buf1 = generateSnapshot();
const buf2 = generateSnapshot();

const diff = [];
let offset = 0;
const step = 16;
do {
const length = Math.min(buf1.length - offset, step);
const slice1 = buf1.slice(offset, offset + length).toString('hex');
const slice2 = buf2.slice(offset, offset + length).toString('hex');
if (slice1 !== slice2) {
diff.push({ offset: '0x' + (offset).toString(16), slice1, slice2 });
}
offset += length;
} while (offset < buf1.length);

assert.strictEqual(offset, buf1.length);
if (offset < buf2.length) {
const length = Math.min(buf2.length - offset, step);
const slice2 = buf2.slice(offset, offset + length).toString('hex');
diff.push({ offset, slice1: '', slice2 });
offset += length;
} while (offset < buf2.length);

assert.deepStrictEqual(diff, []);
assert.strictEqual(buf1.length, buf2.length);
const source1 = generateSnapshot();
const source2 = generateSnapshot();
assert.deepStrictEqual(source1, source2);
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