Allow Angular to pass no browsers to Karma

[Nvveen]

Command

test

Description

Karma has a CLI option --no-browsers to allow Karma to open without any connected browsers. This can be achieved in Angular by passing an empty [] array in karma,conf.js. This is useful when running the dev server in a devcontainer, where no display server and instances of browsers are installed. Manually opening a browser with the ports forwarded then runs the tests like normal.
The issue starts when using the built-in Karma config, but passing either "browsers": "", or the CLI flag "--browsers=\"" to ng test. The line at

angular-cli/packages/angular_devkit/build_angular/src/builders/karma/index.ts

Line 103 in e3bb258

if (options.browsers) {

checks if the browsers option exists, but since the string is empty, the expression is false and the default Karma option of ['Chrome'] is instead used.

Describe the solution you'd like

Changing this line to if (options.browsers != null) and filtering the split array by non-empty strings should solve this particular issue.

Describe alternatives you've considered

No response

[Nvveen]

I am trying to create a PR, but running into issues with building my local fork. yarn build --local fails with TypeError [ERR_INVALID_ARG_TYPE]: The "code" argument must be of type number. Received an instance of Array and commiting my changes throws an error too, Could not read configuration file at /tmp/angular-cli/.ng-dev/config.mjs., because of a precommit hook.

[alan-agius4]

@Nvveen, I have seen that error, to build and create an app you can use yarn admin create <app-name>

But in the case we are going to add this feature, the desired implementation would be to allow --no-browser to be passed from the command line, which will not require filtering the array etc...

See:

angular-cli/packages/angular_devkit/build_angular/src/builders/application/schema.json

Lines 365 to 389 in e3bb258

	"index": {
	"description": "Configures the generation of the application's HTML index.",
	"oneOf": [
	{
	"type": "string",
	"description": "The path of a file to use for the application's HTML index. The filename of the specified path will be used for the generated file and will be created in the root of the application's configured output path."
	},
	{
	"type": "object",
	"description": "",
	"properties": {
	"input": {
	"type": "string",
	"minLength": 1,
	"description": "The path of a file to use for the application's generated HTML index."
	},
	"output": {
	"type": "string",
	"minLength": 1,
	"default": "index.html",
	"description": "The output path of the application's generated HTML index file. The full provided path will be used and will be considered relative to the application's configured output path."
	}
	},
	"required": ["input"]
	},

for an example.

[Nvveen]

@Nvveen, I have seen that error, to build and create an app you can use yarn admin create

I can't commit either, because the file in that error's directory is an '.mts' file, haha. Otherwise I'd gladly submit a PR with your approach, if I can manage.

[angular-robot]

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