Support path resolvers from tsconfig

[lukasIO]

Hi,

in my tsconfig file i have paths set up like this

"compilerOptions": {
		...
		"paths": {
			"$lib/*": ["src/lib/*"]
		}
	},

If I import a module for testing (using loadr, tsm and uvu) the resolution fails as soon as the module/file that I import has a reference to $lib with the following error:
Error [ERR_MODULE_NOT_FOUND]: Cannot find package '$lib' imported from /path/to/lib/utils.ts

[lukeed]

Oh yeah, oops! I'll add this

[lukeed]

Are people expecting this to follow/work with the "extends" key?

Right now, I'm expecting to only support a tsconfig.json file in the process.cwd() root. Perhaps I'd listen in on tsc's -p/--project flag, but that would only set the initial tsconfig.json ... I'm not particularly incline to resolve the closest tsconfig.json per every file loaded – that would be a big perf hit.

If "extends" is defined, it could point to another tsconfig file that has "paths" defined within it. Would also have to follow "extends" recursively until there aren't any more.

[bluwy]

Perhaps we can use https://github.com/dominikg/tsconfck to resolve and parse the tsconfig? It’s currently used in Vite and implements the TypeScript behaviour well. cc @dominikg

[dominikg]

Thanks for tagging me. I should check if "paths" content is actually correctly handled when they are taken from an extended config. Usually relative pathlike values in tsconfig files are rebased to the file they are defined in, but with paths, it's a key/value pair and the value can actually be an array.

[dominikg]

tsconfck does handle paths the same way as typescript itself.

There are a couple of minor differences in tsconfck output, but they should not affect the results of esbuild

• compilerOptions.baseUrl is absolute instead of relative
• files is omitted instead of showing a list of matching files
• extends is kept

Example output of tsconfck and it's tsc equivalent in https://github.com/dominikg/tsconfck/tree/main/tests/fixtures/parse/valid/with_extends/paths

tsconfck parse import-foo.ts

{
  "extends": "../tsconfig.base",
  "compilerOptions": {
    "types": [
      "foo"
    ],
    "strictNullChecks": true,
    "baseUrl": "/home/dominikg/develop/tsconfck/tests/fixtures/parse/valid/with_extends/paths",
    "paths": {
      "$lib": [
        "*",
        "./lib"
      ],
      "$src": [
        "./src"
      ]
    },
    "noImplicitAny": true
  },
  "include": [
    "../src/**/*",
    "../lib/**/*"
  ],
  "watchOptions": {
    "watchFile": "useFsEvents",
    "watchDirectory": "useFsEvents",
    "fallbackPolling": "dynamicPriority"
  },
  "exclude": [
    "../../**/foo/*"
  ]
}

tsc --showConfig

{
    "compilerOptions": {
        "types": [
            "foo"
        ],
        "strictNullChecks": true,
        "noImplicitAny": true,
        "baseUrl": "..",
        "paths": {
            "$lib": [
                "*",
                "./lib"
            ],
            "$src": [
                "./src"
            ]
        }
    },
    "watchOptions": {
        "watchFile": "usefsevents",
        "watchDirectory": "usefsevents",
        "fallbackPolling": "dynamicpriority"
    },
    "files": [
        "./import-foo.ts",
        "../lib/foo.ts"
    ],
    "include": [
        "../src/**/*",
        "../lib/**/*"
    ],
    "exclude": [
        "../../**/foo/*"
    ]
}

[Jamesernator]

Right now, I'm expecting to only support a tsconfig.json file in the process.cwd() root.

This is not particularly useful when using shebangs in general as the tsconfig.json would be in the path with the script not the path the script is being run from.

e.g. I'm currently using ts-node at the moment with it's TS_NODE_PROJECT env var, but having tsconfig auto detected would be considerably more useful than having to deal with the awkward wrapper scripts I'm currently doing.

I'm not particularly incline to resolve the closest tsconfig.json per every file loaded – that would be a big perf hit.

Packages need to do this for their package.json already so I'm not sure why this would be any more expensive for tsconfig.json. Optionally you could make a requirement to link tsconfig.json from the package.json to hint that it is required.

[lukeed]

What packages have to do and what tsm has to do/is doing are completely separate. Right now, tsm only looks at each file as it's loaded. At most it's checking fs existence during path resolution, but no extra/unnecessary file reads beyond the transformation step itself.

[Ocupe]

hey 👋 , thank you for this super fast testing tool!
I'm lacking the background knowledge to see a work around in the above conversation. Is there a work around or a solution for this? :)

[dominikg]

No workaround. But implementing it with tsconfck would be just a couple of lines.
the tsconfig needs to be set on esbuild transform call here

tsm/src/loader.ts

Line 118 in 73b8c77

sourcefile: context.url,

, as tsconfigRaw iirc.

[Ocupe]

Thank you for your tip @dominikg! I'm struggling with it tough. Is this going into the right direction?

import { parse } from "tsconfck";

...

export const transformSource: Transform = async function ( source, context, xform) {
	let options = await toOptions(context.url);
	if (options == null) return xform(source, context, xform);

	const {
		tsconfigFile, // full path to found tsconfig
		tsconfig, // tsconfig object including merged values from extended configs
		extended, // separate unmerged results of all tsconfig files that contributed to tsconfig
		solution, // solution result if tsconfig is part of a solution
		referenced, // referenced tsconfig results if tsconfig is a solution
	} = await parse(context.url);

	// TODO: decode SAB/U8 correctly
	esbuild = esbuild || await import('esbuild');
	let result = await esbuild.transform(source.toString(), {
		...options,
		sourcefile: context.url,
		format: context.format === "module" ? "esm" : "cjs",
		tsconfigRaw: tsconfig,
	});

	return { source: result.code };
};

[dominikg]

You don't need to define the unused constants and if there is a chance this code runs multiple times if sourcefile imports other files, using the cache feature of tsconfck might be a good idea.

Not 100% sure if this location is the best to do it or if it should be in toOptions, maybe @lukeed has a preference on that

[yoursunny]

NDNts monorepo is currently using @k-foss/ts-esnode but I found myself adding more and more monkeypatches to make it work with recent Node versions.
I'm looking to switch to tsm but the lack of paths is the first blocker.

Are people expecting this to follow/work with the "extends" key?

My use case do not require this feature.

However, I hope I can customize which tsconfig.json is loaded via TS_CONFIG_PATH environment variable.
This would allow me to prepare a special tsconfig.json that contains all the necessary paths.

[lukeed]

Is that ENV a known/standard variable? I was planning on doing a --tsm-tsconfig flag and have that be it. Only left I have left to investigate is whether or not each file actually has to search for its closest tsconfig file.

[yoursunny]

TS_CONFIG_PATH is not a standard.
It's just what @k-foss/ts-esnode uses to locate a tsconfig.json file.
K-FOSS/TS-ESNode#64

Having --tsm-tsconfig flag is OK.
In my use case, I can provide an absolute path, so that there's no searching involved.

[bhvngt]

This will be a great edition to this package.

I do use extended tsconfig.json as part of my monorepo to maintain consistency for source path alias.

As a workaround I have been using require hooks from module-alias. This works with uvu command line -- uvu -r tsm -r module-alias/register tests where my tests are using path alias.

However it does not work when I use it directly with node -- node --loader tsm -r module-alias/register src/m1/a.ts where a.ts is using path-alias.

Hopefully, I wont have to use module-alias if support for path-alias is baked in.