test: add integration tests for ChunkGraph and ChunkGroup integrity by aryanraj45 · Pull Request #20772 · webpack/webpack

aryanraj45 · 2026-04-03T19:11:03Z

Summary

Added integration tests for core graph integrity methods in ChunkGraph.js and lib/ChunkGroup.js. Methods like replaceModule, connectChunkAndModule, and disconnectChunkAndModule were previously hit by high-level tests but had gaps in verifying specific manual manipulation safety during build hooks.

The new suite in test/GraphIntegrity.test.js ensures that graph state remains valid when modules are re-mapped or disconnected within the optimize phase. Standalone coverage for lib/ChunkGraph.js jumped by ~26%.

What kind of change does this PR introduce?

test

Did you add tests for your changes?

Yes, integrated test/GraphIntegrity.test.js.

Does this PR introduce a breaking change?

No.

If relevant, what needs to be documented once your changes are merged or what have you already documented?

N/A.

Use of AI

None

changeset-bot · 2026-04-03T19:11:09Z

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Copilot

Pull request overview

Adds a new integration-level test to exercise core ChunkGraph / ChunkGroup graph-manipulation APIs during the compilation.optimize phase, aiming to validate integrity when plugins mutate graph relationships inside build hooks.

Changes:

Introduces test/GraphIntegrity.test.js to run a production compilation against test/fixtures and mutate ChunkGraph during optimize.
Adds assertions around ChunkGraph.replaceModule, connectChunkAndModule, and disconnectChunkAndModule.
Touches ChunkGroup by invoking getChildren() during the same optimization hook.

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Copilot · 2026-04-03T19:16:30Z

+					chunkGraph.replaceModule(oldModule, newModule);
+
+					const hasNew = chunkGraph.isModuleInChunk(newModule, chunk);
+					const hasOld = chunkGraph.isModuleInChunk(oldModule, chunk);
+
+					if (!hasNew || hasOld) {
+						throw new Error("Module replacement failed in ChunkGraph");
+					}
+
+					chunkGraph.connectChunkAndModule(chunk, oldModule);
+					chunkGraph.disconnectChunkAndModule(chunk, oldModule);
+
+					const [group] = compilation.chunkGroups;
+					if (group) {
+						group.getChildren();


replaceModule(oldModule, newModule) replaces a real compilation module with a plain object that is not part of compilation.modules. After this hook, later phases (e.g. chunk hashing via chunk.updateHash → chunkGraph.getModuleHash) will try to access hash info for newModule and will throw because no hashes were ever set for it. This makes the test (and potentially the build) fail/flaky. Use an actual Module instance that participates in the compilation (or perform the replace + assertions + full revert within the optimize hook so the compilation continues with a valid graph), and consider calling compilation.checkConstraints() after the mutation to validate integrity.

Suggested change

chunkGraph.replaceModule(oldModule, newModule);

const hasNew = chunkGraph.isModuleInChunk(newModule, chunk);

const hasOld = chunkGraph.isModuleInChunk(oldModule, chunk);

if (!hasNew || hasOld) {

throw new Error("Module replacement failed in ChunkGraph");

}

chunkGraph.connectChunkAndModule(chunk, oldModule);

chunkGraph.disconnectChunkAndModule(chunk, oldModule);

const [group] = compilation.chunkGroups;

if (group) {

group.getChildren();

try {

chunkGraph.replaceModule(oldModule, newModule);

const hasNew = chunkGraph.isModuleInChunk(newModule, chunk);

const hasOld = chunkGraph.isModuleInChunk(oldModule, chunk);

if (!hasNew || hasOld) {

throw new Error("Module replacement failed in ChunkGraph");

}

const [group] = compilation.chunkGroups;

if (group) {

group.getChildren();

}

} finally {

chunkGraph.replaceModule(newModule, oldModule);

chunkGraph.connectChunkAndModule(chunk, oldModule);

chunkGraph.disconnectChunkAndModule(chunk, oldModule);

compilation.checkConstraints();

Copilot · 2026-04-03T19:16:31Z

+				const modules = [...chunkGraph.getChunkModulesIterable(chunk)];
+
+				if (modules.length >= 1) {
+					const oldModule = modules[0];
+					const newModule = {
+						identifier: () => "mock-module-identifier",
+						getSourceTypes: () => ["javascript"],
+						size: () => 0,
+						identifierIndex: 0
+					};
+
+					chunkGraph.replaceModule(oldModule, newModule);
+
+					const hasNew = chunkGraph.isModuleInChunk(newModule, chunk);
+					const hasOld = chunkGraph.isModuleInChunk(oldModule, chunk);
+
+					if (!hasNew || hasOld) {
+						throw new Error("Module replacement failed in ChunkGraph");
+					}
+
+					chunkGraph.connectChunkAndModule(chunk, oldModule);
+					chunkGraph.disconnectChunkAndModule(chunk, oldModule);
+
+					const [group] = compilation.chunkGroups;
+					if (group) {
+						group.getChildren();
+					}


The if (modules.length >= 1) guard allows this test to become a no-op (and still pass) if no modules are present or if chunk resolves unexpectedly. Since this is an integration integrity test, it should fail loudly when preconditions aren’t met (e.g., assert a non-empty module list / expected module count) so the test actually validates behavior.

Suggested change

const modules = [...chunkGraph.getChunkModulesIterable(chunk)];

if (modules.length >= 1) {

const oldModule = modules[0];

const newModule = {

identifier: () => "mock-module-identifier",

getSourceTypes: () => ["javascript"],

size: () => 0,

identifierIndex: 0

};

chunkGraph.replaceModule(oldModule, newModule);

const hasNew = chunkGraph.isModuleInChunk(newModule, chunk);

const hasOld = chunkGraph.isModuleInChunk(oldModule, chunk);

if (!hasNew || hasOld) {

throw new Error("Module replacement failed in ChunkGraph");

}

chunkGraph.connectChunkAndModule(chunk, oldModule);

chunkGraph.disconnectChunkAndModule(chunk, oldModule);

const [group] = compilation.chunkGroups;

if (group) {

group.getChildren();

}

if (!chunk) {

throw new Error("Expected compilation to contain at least one chunk");

}

const modules = [...chunkGraph.getChunkModulesIterable(chunk)];

if (modules.length < 1) {

throw new Error("Expected chunk to contain at least one module");

}

const oldModule = modules[0];

const newModule = {

identifier: () => "mock-module-identifier",

getSourceTypes: () => ["javascript"],

size: () => 0,

identifierIndex: 0

};

chunkGraph.replaceModule(oldModule, newModule);

const hasNew = chunkGraph.isModuleInChunk(newModule, chunk);

const hasOld = chunkGraph.isModuleInChunk(oldModule, chunk);

if (!hasNew || hasOld) {

throw new Error("Module replacement failed in ChunkGraph");

}

chunkGraph.connectChunkAndModule(chunk, oldModule);

chunkGraph.disconnectChunkAndModule(chunk, oldModule);

const [group] = compilation.chunkGroups;

if (group) {

group.getChildren();

Please fix it

Copilot · 2026-04-03T19:16:31Z

+
+					const [group] = compilation.chunkGroups;
+					if (group) {
+						group.getChildren();


Calling group.getChildren() without any assertion doesn’t validate ChunkGroup integrity, and it won’t catch parent/child linkage issues (the method just returns a value). If the goal is integrity checking, use an invariant check (e.g. group.checkConstraints()) or assert expected parent/child relationships so failures are actionable.

Suggested change

group.getChildren();

group.checkConstraints();

aryanraj45 · 2026-04-07T15:53:01Z

@alexander-akait I have addressed the co-pilot review .can u please take a view Thanks!

alexander-akait · 2026-04-08T00:11:54Z

+			});
+		});
+	}, 60000);
+});


it is possible to rewrite this test to configCases? You can write a small custom plugin which make the same, I don't like unit tests for such cases because it is hard to maintain and hard to catch the real errors/problems

aryanraj45 · 2026-04-08T19:56:59Z

@alexander-akait thanks for the suggestion i have completely removed the unit test and migrated the logic to configCases/chunk-graph/graph-integrity.also it increase the line coverage from 26% to 38% Please take a view Thanks

codspeed-hq · 2026-04-10T11:24:55Z

Merging this PR will degrade performance by 44.89%

❌ 2 regressed benchmarks
✅ 142 untouched benchmarks

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Mode	Benchmark	`BASE`	`HEAD`	Efficiency
❌	Memory	`benchmark "asset-modules-source", scenario '{"name":"mode-development","mode":"development"}'`	506.8 KB	919.6 KB	-44.89%
❌	Memory	`benchmark "asset-modules-source", scenario '{"name":"mode-development-rebuild","mode":"development","watch":true}'`	265.9 KB	389 KB	-31.65%

_{Comparing aryanraj45:test/graph-integrity (e8f9e44) with main (a98fd62)}

alexander-akait · 2026-04-10T16:51:04Z

@aryanraj45 looks good let's fix lint and we can merge

alexander-akait · 2026-04-10T16:52:03Z

+							size: () => 0
+						};
+
+						chunkGraph.replaceModule(m, mock);


you can use // @ts-expect-error for tests comment to avoid types problems

@alexander-akait fixed the lint and added the comment please take a view thanks!

Please always add for tests, we have an eslint rule that requires to write comment why it is expected

done please take a look thanks!

aryanraj45 · 2026-04-13T22:15:25Z

@alexander-akait all the required CI passed!
thanks

github-actions · 2026-04-14T11:06:21Z

This PR is packaged and the instant preview is available (5310112).

Install it locally:

npm

npm i -D webpack@https://pkg.pr.new/webpack@5310112

yarn

yarn add -D webpack@https://pkg.pr.new/webpack@5310112

pnpm

pnpm add -D webpack@https://pkg.pr.new/webpack@5310112

test: add integration tests for ChunkGraph and ChunkGroup integrity

ccde5a0

Copilot AI review requested due to automatic review settings April 3, 2026 19:11

Copilot started reviewing on behalf of aryanraj45 April 3, 2026 19:11 View session

Copilot AI reviewed Apr 3, 2026

View reviewed changes

test: address review feedback for GraphIntegrity (fix silent guard)

58f390b

aryanraj45 requested a review from alexander-akait April 6, 2026 15:09

alexander-akait reviewed Apr 8, 2026

View reviewed changes

test: migrate GraphIntegrity unit test to configCases integration suite

3422b00

aryanraj45 requested a review from alexander-akait April 8, 2026 19:57

alexander-akait reviewed Apr 10, 2026

View reviewed changes

test: fix lint and add ts-expect-error as requested

a0fac8b

aryanraj45 requested a review from alexander-akait April 10, 2026 20:05

aryanraj45 added 2 commits April 14, 2026 00:01

test: add rationale for @ts-expect-error as requested

056fa21

test: add rationale for @ts-expect-error and fix coverage

e8f9e44

alexander-akait approved these changes Apr 14, 2026

View reviewed changes

alexander-akait merged commit 5310112 into webpack:main Apr 14, 2026
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Merging this PR will degrade performance by 44.89%

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