SchematicTestRunner.runExternalSchematic fails with "The encoded data was not valid for encoding utf-8"

[daniel-sc]

Command

other

Is this a regression?

• Yes, this behavior used to work in the previous version

The previous version in which this bug was not present was

17.0.0

Description

With v18.0.0-rc.1 under some conditions (which exactly is unclear to me) SchematicTestRunner.runExternalSchematic fails with the following error: "The encoded data was not valid for encoding utf-8"

See e.g. https://github.com/daniel-sc/ng-extract-i18n-merge/actions/runs/9091527710/job/24986317152?pr=111

The exact same test runs fine with angular 17: https://github.com/daniel-sc/ng-extract-i18n-merge/actions/runs/9091527710/job/24986316954?pr=111

This is the line were it fails: https://github.com/daniel-sc/ng-extract-i18n-merge/blob/master/schematics/ng-add/index.spec.ts#L45 (unsure why the first invocation succeeds..)

Minimal Reproduction

1. Checkout branch angular-18 from https://github.com/daniel-sc/ng-extract-i18n-merge
2. remove package-lock.json
3. run npm i --save-exact "@angular-devkit/architect@0.1800.0-rc.1" "@angular-devkit/core@18.0.0-rc.1" "@angular-devkit/schematics@18.0.0-rc.1" "@schematics/angular@18.0.0-rc.1" "@angular-devkit/build-angular@18.0.0-rc.1" "@angular/core@18.0.0-rc.1" "@angular/compiler-cli@18.0.0-rc.1"
4. run npm run build
5. run npm run test-coverage

Exception or Error

The encoded data was not valid for encoding utf-8
TypeError: The encoded data was not valid for encoding utf-8
    at TextDecoder.decode (node:internal/encoding:449:16)
    at C:\projekte\ng-extract-i18n-merge\node_modules\@angular-devkit\schematics\src\rules\template.js:38:44
    at C:\projekte\ng-extract-i18n-merge\node_modules\@angular-devkit\schematics\src\rules\base.js:135:23
    at C:\projekte\ng-extract-i18n-merge\node_modules\@angular-devkit\schematics\src\rules\base.js:89:20
    at C:\projekte\ng-extract-i18n-merge\node_modules\@angular-devkit\schematics\src\rules\base.js:113:30
    at C:\projekte\ng-extract-i18n-merge\node_modules\@angular-devkit\schematics\src\tree\host-tree.js:278:13
    at C:\projekte\ng-extract-i18n-merge\node_modules\@angular-devkit\schematics\src\tree\host-tree.js:51:61
    at Array.forEach (<anonymous>)
    at HostDirEntry.visit (C:\projekte\ng-extract-i18n-merge\node_modules\@angular-devkit\schematics\src\tree\host-tree.js:51:43)
    at HostCreateTree.visit (C:\projekte\ng-extract-i18n-merge\node_modules\@angular-devkit\schematics\src\tree\host-tree.js:277:19)
    at C:\projekte\ng-extract-i18n-merge\node_modules\@angular-devkit\schematics\src\rules\base.js:109:14
    at callRuleAsync (C:\projekte\ng-extract-i18n-merge\node_modules\@angular-devkit\schematics\src\rules\call.js:77:24)
    at C:\projekte\ng-extract-i18n-merge\node_modules\@angular-devkit\schematics\src\rules\call.js:69:63
    at doInnerSub (C:\projekte\ng-extract-i18n-merge\node_modules\rxjs\src\internal\operators\mergeInternals.ts:71:15)
    at outerNext (C:\projekte\ng-extract-i18n-merge\node_modules\rxjs\src\internal\operators\mergeInternals.ts:53:58)
    at OperatorSubscriber._this._next (C:\projekte\ng-extract-i18n-merge\node_modules\rxjs\src\internal\operators\OperatorSubscriber.ts:70:13)
    at OperatorSubscriber.Object.<anonymous>.Subscriber.next (C:\projekte\ng-extract-i18n-merge\node_modules\rxjs\src\internal\Subscriber.ts:75:12)
    at C:\projekte\ng-extract-i18n-merge\node_modules\rxjs\src\internal\operators\mergeInternals.ts:85:24
    at OperatorSubscriber._this._next (C:\projekte\ng-extract-i18n-merge\node_modules\rxjs\src\internal\operators\OperatorSubscriber.ts:70:13)
    at OperatorSubscriber.Object.<anonymous>.Subscriber.next (C:\projekte\ng-extract-i18n-merge\node_modules\rxjs\src\internal\Subscriber.ts:75:12)
    at C:\projekte\ng-extract-i18n-merge\node_modules\rxjs\src\internal\observable\innerFrom.ts:90:24

Your Environment

Angular CLI: 17.3.3
Node: 20.12.0
Package Manager: npm 10.5.0
OS: win32 x64

Angular: 18.0.0-rc.1
... compiler-cli, core

Package                      Version
------------------------------------------------------
@angular-devkit/architect    0.1800.0-rc.1
@angular-devkit/core         18.0.0-rc.1
@angular-devkit/schematics   18.0.0-rc.1
@schematics/angular          18.0.0-rc.1
typescript                   5.4.5

Anything else relevant?

No response

[alan-agius4]

This is caused by a long standing bug in Jest which causes instanceof not to work correctly.

See: jestjs/jest#2549

For context this is happening due to the changes in #27570

[daniel-sc]

@alan-agius4 thanks for the pointers!

It would be great if this could be adressed, as this breaks unit tests of schematics with jest and probably impacts some libraries..

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